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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// The SWGL depth buffer is roughly organized as a span buffer where each row
+// of the depth buffer is a list of spans, and each span has a constant depth
+// and a run length (represented by DepthRun). The span from start..start+count
+// is placed directly at that start index in the row's array of runs, so that
+// there is no need to explicitly record the start index at all. This also
+// avoids the need to move items around in the run array to manage insertions
+// since space is implicitly always available for a run between any two
+// pre-existing runs. Linkage from one run to the next is implicitly defined by
+// the count, so if a run exists from start..start+count, the next run will
+// implicitly pick up right at index start+count where that preceding run left
+// off. All of the DepthRun items that are after the head of the run can remain
+// uninitialized until the run needs to be split and a new run needs to start
+// somewhere in between.
+// For uses like perspective-correct rasterization or with a discard mask, a
+// run is not an efficient representation, and it is more beneficial to have
+// a flattened array of individual depth samples that can be masked off easily.
+// To support this case, the first run in a given row's run array may have a
+// zero count, signaling that this entire row is flattened. Critically, the
+// depth and count fields in DepthRun are ordered (endian-dependently) so that
+// the DepthRun struct can be interpreted as a sign-extended int32_t depth. It
+// is then possible to just treat the entire row as an array of int32_t depth
+// samples that can be processed with SIMD comparisons, since the count field
+// behaves as just the sign-extension of the depth field. The count field is
+// limited to 8 bits so that we can support depth values up to 24 bits.
+// When a depth buffer is cleared, each row is initialized to a maximal runs
+// spanning the entire row. In the normal case, the depth buffer will continue
+// to manage itself as a list of runs. If perspective or discard is used for
+// a given row, the row will be converted to the flattened representation to
+// support it, after which it will only ever revert back to runs if the depth
+// buffer is cleared.
+
+// The largest 24-bit depth value supported.
+constexpr uint32_t MAX_DEPTH_VALUE = 0xFFFFFF;
+// The longest 8-bit depth run that is supported, aligned to SIMD chunk size.
+constexpr uint32_t MAX_DEPTH_RUN = 255 & ~3;
+
+struct DepthRun {
+ // Ensure that depth always occupies the LSB and count the MSB so that we
+ // can sign-extend depth just by setting count to zero, marking it flat.
+ // When count is non-zero, then this is interpreted as an actual run and
+ // depth is read in isolation.
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+ uint32_t depth : 24;
+ uint32_t count : 8;
+#else
+ uint32_t count : 8;
+ uint32_t depth : 24;
+#endif
+
+ DepthRun() = default;
+ DepthRun(uint32_t depth, uint8_t count) : depth(depth), count(count) {}
+
+ // If count is zero, this is actually a flat depth sample rather than a run.
+ bool is_flat() const { return !count; }
+
+ // Compare a source depth from rasterization with a stored depth value.
+ template <int FUNC>
+ ALWAYS_INLINE bool compare(uint32_t src) const {
+ switch (FUNC) {
+ case GL_LEQUAL:
+ return src <= depth;
+ case GL_LESS:
+ return src < depth;
+ case GL_ALWAYS:
+ return true;
+ default:
+ assert(false);
+ return false;
+ }
+ }
+};
+
+// Fills runs at the given position with the given depth up to the span width.
+static ALWAYS_INLINE void set_depth_runs(DepthRun* runs, uint32_t depth,
+ uint32_t width) {
+ // If the width exceeds the maximum run size, then we need to output clamped
+ // runs first.
+ for (; width >= MAX_DEPTH_RUN;
+ runs += MAX_DEPTH_RUN, width -= MAX_DEPTH_RUN) {
+ *runs = DepthRun(depth, MAX_DEPTH_RUN);
+ }
+ // If there are still any left over samples to fill under the maximum run
+ // size, then output one last run for them.
+ if (width > 0) {
+ *runs = DepthRun(depth, width);
+ }
+}
+
+// A cursor for reading and modifying a row's depth run array. It locates
+// and iterates through a desired span within all the runs, testing if
+// the depth of this span passes or fails the depth test against existing
+// runs. If desired, new runs may be inserted to represent depth occlusion
+// from this span in the run array.
+struct DepthCursor {
+ // Current position of run the cursor has advanced to.
+ DepthRun* cur = nullptr;
+ // The start of the remaining potential samples in the desired span.
+ DepthRun* start = nullptr;
+ // The end of the potential samples in the desired span.
+ DepthRun* end = nullptr;
+
+ DepthCursor() = default;
+
+ // Construct a cursor with runs for a given row's run array and the bounds
+ // of the span we wish to iterate within it.
+ DepthCursor(DepthRun* runs, int num_runs, int span_offset, int span_count)
+ : cur(runs), start(&runs[span_offset]), end(start + span_count) {
+ // This cursor should never iterate over flat runs
+ assert(!runs->is_flat());
+ DepthRun* end_runs = &runs[num_runs];
+ // Clamp end of span to end of row
+ if (end > end_runs) {
+ end = end_runs;
+ }
+ // If the span starts past the end of the row, just advance immediately
+ // to it to signal that we're done.
+ if (start >= end_runs) {
+ cur = end_runs;
+ start = end_runs;
+ return;
+ }
+ // Otherwise, find the first depth run that contains the start of the span.
+ // If the span starts after the given run, then we need to keep searching
+ // through the row to find an appropriate run. The check above already
+ // guaranteed that the span starts within the row's runs, and the search
+ // won't fall off the end.
+ for (;;) {
+ assert(cur < end);
+ DepthRun* next = cur + cur->count;
+ if (start < next) {
+ break;
+ }
+ cur = next;
+ }
+ }
+
+ // The cursor is valid if the current position is at the end or if the run
+ // contains the start position.
+ bool valid() const {
+ return cur >= end || (cur <= start && start < cur + cur->count);
+ }
+
+ // Skip past any initial runs that fail the depth test. If we find a run that
+ // would pass, then return the accumulated length between where we started
+ // and that position. Otherwise, if we fall off the end, return -1 to signal
+ // that there are no more passed runs at the end of this failed region and
+ // so it is safe for the caller to stop processing any more regions in this
+ // row.
+ template <int FUNC>
+ int skip_failed(uint32_t val) {
+ assert(valid());
+ DepthRun* prev = start;
+ while (cur < end) {
+ if (cur->compare<FUNC>(val)) {
+ return start - prev;
+ }
+ cur += cur->count;
+ start = cur;
+ }
+ return -1;
+ }
+
+ // Helper to convert function parameters into template parameters to hoist
+ // some checks out of inner loops.
+ ALWAYS_INLINE int skip_failed(uint32_t val, GLenum func) {
+ switch (func) {
+ case GL_LEQUAL:
+ return skip_failed<GL_LEQUAL>(val);
+ case GL_LESS:
+ return skip_failed<GL_LESS>(val);
+ default:
+ assert(false);
+ return -1;
+ }
+ }
+
+ // Find a region of runs that passes the depth test. It is assumed the caller
+ // has called skip_failed first to skip past any runs that failed the depth
+ // test. This stops when it finds a run that fails the depth test or we fall
+ // off the end of the row. If the write mask is enabled, this will insert runs
+ // to represent this new region that passed the depth test. The length of the
+ // region is returned.
+ template <int FUNC, bool MASK>
+ int check_passed(uint32_t val) {
+ assert(valid());
+ DepthRun* prev = cur;
+ while (cur < end) {
+ if (!cur->compare<FUNC>(val)) {
+ break;
+ }
+ DepthRun* next = cur + cur->count;
+ if (next > end) {
+ if (MASK) {
+ // Chop the current run where the end of the span falls, making a new
+ // run from the end of the span till the next run. The beginning of
+ // the current run will be folded into the run from the start of the
+ // passed region before returning below.
+ *end = DepthRun(cur->depth, next - end);
+ }
+ // If the next run starts past the end, then just advance the current
+ // run to the end to signal that we're now at the end of the row.
+ next = end;
+ }
+ cur = next;
+ }
+ // If we haven't advanced past the start of the span region, then we found
+ // nothing that passed.
+ if (cur <= start) {
+ return 0;
+ }
+ // If 'end' fell within the middle of a passing run, then 'cur' will end up
+ // pointing at the new partial run created at 'end' where the passing run
+ // was split to accommodate starting in the middle. The preceding runs will
+ // be fixed below to properly join with this new split.
+ int passed = cur - start;
+ if (MASK) {
+ // If the search started from a run before the start of the span, then
+ // edit that run to meet up with the start.
+ if (prev < start) {
+ prev->count = start - prev;
+ }
+ // Create a new run for the entirety of the passed samples.
+ set_depth_runs(start, val, passed);
+ }
+ start = cur;
+ return passed;
+ }
+
+ // Helper to convert function parameters into template parameters to hoist
+ // some checks out of inner loops.
+ template <bool MASK>
+ ALWAYS_INLINE int check_passed(uint32_t val, GLenum func) {
+ switch (func) {
+ case GL_LEQUAL:
+ return check_passed<GL_LEQUAL, MASK>(val);
+ case GL_LESS:
+ return check_passed<GL_LESS, MASK>(val);
+ default:
+ assert(false);
+ return 0;
+ }
+ }
+
+ ALWAYS_INLINE int check_passed(uint32_t val, GLenum func, bool mask) {
+ return mask ? check_passed<true>(val, func)
+ : check_passed<false>(val, func);
+ }
+
+ // Fill a region of runs with a given depth value, bypassing any depth test.
+ ALWAYS_INLINE void fill(uint32_t depth) {
+ check_passed<GL_ALWAYS, true>(depth);
+ }
+};
+
+// Initialize a depth texture by setting the first run in each row to encompass
+// the entire row.
+void Texture::init_depth_runs(uint32_t depth) {
+ if (!buf) return;
+ DepthRun* runs = (DepthRun*)buf;
+ for (int y = 0; y < height; y++) {
+ set_depth_runs(runs, depth, width);
+ runs += stride() / sizeof(DepthRun);
+ }
+ set_cleared(true);
+}
+
+// Fill a portion of the run array with flattened depth samples.
+static ALWAYS_INLINE void fill_flat_depth(DepthRun* dst, size_t n,
+ uint32_t depth) {
+ fill_n((uint32_t*)dst, n, depth);
+}
+
+// Fills a scissored region of a depth texture with a given depth.
+void Texture::fill_depth_runs(uint32_t depth, const IntRect& scissor) {
+ if (!buf) return;
+ assert(cleared());
+ IntRect bb = bounds().intersection(scissor - offset);
+ DepthRun* runs = (DepthRun*)sample_ptr(0, bb.y0);
+ for (int rows = bb.height(); rows > 0; rows--) {
+ if (bb.width() >= width) {
+ // If the scissor region encompasses the entire row, reset the row to a
+ // single run encompassing the entire row.
+ set_depth_runs(runs, depth, width);
+ } else if (runs->is_flat()) {
+ // If the row is flattened, just directly fill the portion of the row.
+ fill_flat_depth(&runs[bb.x0], bb.width(), depth);
+ } else {
+ // Otherwise, if we are still using runs, then set up a cursor to fill
+ // it with depth runs.
+ DepthCursor(runs, width, bb.x0, bb.width()).fill(depth);
+ }
+ runs += stride() / sizeof(DepthRun);
+ }
+}
+
+using ZMask = I32;
+
+#if USE_SSE2
+# define ZMASK_NONE_PASSED 0xFFFF
+# define ZMASK_ALL_PASSED 0
+static inline uint32_t zmask_code(ZMask mask) {
+ return _mm_movemask_epi8(mask);
+}
+#else
+# define ZMASK_NONE_PASSED 0xFFFFFFFFU
+# define ZMASK_ALL_PASSED 0
+static inline uint32_t zmask_code(ZMask mask) {
+ return bit_cast<uint32_t>(CONVERT(mask, U8));
+}
+#endif
+
+// Interprets items in the depth buffer as sign-extended 32-bit depth values
+// instead of as runs. Returns a mask that signals which samples in the given
+// chunk passed or failed the depth test with given Z value.
+template <bool DISCARD>
+static ALWAYS_INLINE bool check_depth(I32 src, DepthRun* zbuf, ZMask& outmask,
+ int span = 4) {
+ // SSE2 does not support unsigned comparison. So ensure Z value is
+ // sign-extended to int32_t.
+ I32 dest = unaligned_load<I32>(zbuf);
+ // Invert the depth test to check which pixels failed and should be discarded.
+ ZMask mask = ctx->depthfunc == GL_LEQUAL
+ ?
+ // GL_LEQUAL: Not(LessEqual) = Greater
+ ZMask(src > dest)
+ :
+ // GL_LESS: Not(Less) = GreaterEqual
+ ZMask(src >= dest);
+ // Mask off any unused lanes in the span.
+ mask |= ZMask(span) < ZMask{1, 2, 3, 4};
+ if (zmask_code(mask) == ZMASK_NONE_PASSED) {
+ return false;
+ }
+ if (!DISCARD && ctx->depthmask) {
+ unaligned_store(zbuf, (mask & dest) | (~mask & src));
+ }
+ outmask = mask;
+ return true;
+}
+
+static ALWAYS_INLINE I32 packDepth() {
+ return cast(fragment_shader->gl_FragCoord.z * MAX_DEPTH_VALUE);
+}
+
+static ALWAYS_INLINE void discard_depth(I32 src, DepthRun* zbuf, I32 mask) {
+ if (ctx->depthmask) {
+ I32 dest = unaligned_load<I32>(zbuf);
+ mask |= fragment_shader->swgl_IsPixelDiscarded;
+ unaligned_store(zbuf, (mask & dest) | (~mask & src));
+ }
+}
+
+static ALWAYS_INLINE void mask_output(uint32_t* buf, ZMask zmask,
+ int span = 4) {
+ WideRGBA8 r = pack_pixels_RGBA8();
+ PackedRGBA8 dst = load_span<PackedRGBA8>(buf, span);
+ if (blend_key) r = blend_pixels(buf, dst, r, span);
+ PackedRGBA8 mask = bit_cast<PackedRGBA8>(zmask);
+ store_span(buf, (mask & dst) | (~mask & pack(r)), span);
+}
+
+template <bool DISCARD>
+static ALWAYS_INLINE void discard_output(uint32_t* buf, int span = 4) {
+ mask_output(buf, fragment_shader->swgl_IsPixelDiscarded, span);
+}
+
+template <>
+ALWAYS_INLINE void discard_output<false>(uint32_t* buf, int span) {
+ WideRGBA8 r = pack_pixels_RGBA8();
+ if (blend_key)
+ r = blend_pixels(buf, load_span<PackedRGBA8>(buf, span), r, span);
+ store_span(buf, pack(r), span);
+}
+
+static ALWAYS_INLINE void mask_output(uint8_t* buf, ZMask zmask, int span = 4) {
+ WideR8 r = pack_pixels_R8();
+ WideR8 dst = unpack(load_span<PackedR8>(buf, span));
+ if (blend_key) r = blend_pixels(buf, dst, r, span);
+ WideR8 mask = packR8(zmask);
+ store_span(buf, pack((mask & dst) | (~mask & r)), span);
+}
+
+template <bool DISCARD>
+static ALWAYS_INLINE void discard_output(uint8_t* buf, int span = 4) {
+ mask_output(buf, fragment_shader->swgl_IsPixelDiscarded, span);
+}
+
+template <>
+ALWAYS_INLINE void discard_output<false>(uint8_t* buf, int span) {
+ WideR8 r = pack_pixels_R8();
+ if (blend_key)
+ r = blend_pixels(buf, unpack(load_span<PackedR8>(buf, span)), r, span);
+ store_span(buf, pack(r), span);
+}
+
+struct ClipRect {
+ float x0;
+ float y0;
+ float x1;
+ float y1;
+
+ explicit ClipRect(const IntRect& i)
+ : x0(i.x0), y0(i.y0), x1(i.x1), y1(i.y1) {}
+ explicit ClipRect(const Texture& t) : ClipRect(ctx->apply_scissor(t)) {
+ // If blending is enabled, set blend_key to reflect the resolved blend
+ // state for the currently drawn primitive.
+ if (ctx->blend) {
+ blend_key = ctx->blend_key;
+ if (swgl_ClipFlags) {
+ // If there is a blend override set, replace the blend key with it.
+ if (swgl_ClipFlags & SWGL_CLIP_FLAG_BLEND_OVERRIDE) {
+ blend_key = swgl_BlendOverride;
+ }
+ // If a clip mask is available, set up blending state to use the clip
+ // mask.
+ if (swgl_ClipFlags & SWGL_CLIP_FLAG_MASK) {
+ assert(swgl_ClipMask->format == TextureFormat::R8);
+ // Constrain the clip mask bounds to always fall within the clip mask.
+ swgl_ClipMaskBounds.intersect(IntRect{0, 0, int(swgl_ClipMask->width),
+ int(swgl_ClipMask->height)});
+ // The clip mask offset is relative to the viewport.
+ swgl_ClipMaskOffset += ctx->viewport.origin() - t.offset;
+ // The clip mask bounds are relative to the clip mask offset.
+ swgl_ClipMaskBounds.offset(swgl_ClipMaskOffset);
+ // Finally, constrain the clip rectangle by the clip mask bounds.
+ intersect(swgl_ClipMaskBounds);
+ // Modify the blend key so that it will use the clip mask while
+ // blending.
+ restore_clip_mask();
+ }
+ if (swgl_ClipFlags & SWGL_CLIP_FLAG_AA) {
+ // Modify the blend key so that it will use AA while blending.
+ restore_aa();
+ }
+ }
+ } else {
+ blend_key = BLEND_KEY_NONE;
+ swgl_ClipFlags = 0;
+ }
+ }
+
+ FloatRange x_range() const { return {x0, x1}; }
+
+ void intersect(const IntRect& c) {
+ x0 = max(x0, float(c.x0));
+ y0 = max(y0, float(c.y0));
+ x1 = min(x1, float(c.x1));
+ y1 = min(y1, float(c.y1));
+ }
+
+ template <typename P>
+ void set_clip_mask(int x, int y, P* buf) const {
+ if (swgl_ClipFlags & SWGL_CLIP_FLAG_MASK) {
+ swgl_SpanBuf = buf;
+ swgl_ClipMaskBuf = (uint8_t*)swgl_ClipMask->buf +
+ (y - swgl_ClipMaskOffset.y) * swgl_ClipMask->stride +
+ (x - swgl_ClipMaskOffset.x);
+ }
+ }
+
+ template <typename P>
+ bool overlaps(int nump, const P* p) const {
+ // Generate a mask of which side of the clip rect all of a polygon's points
+ // fall inside of. This is a cheap conservative estimate of whether the
+ // bounding box of the polygon might overlap the clip rect, rather than an
+ // exact test that would require multiple slower line intersections.
+ int sides = 0;
+ for (int i = 0; i < nump; i++) {
+ sides |= p[i].x < x1 ? (p[i].x > x0 ? 1 | 2 : 1) : 2;
+ sides |= p[i].y < y1 ? (p[i].y > y0 ? 4 | 8 : 4) : 8;
+ }
+ return sides == 0xF;
+ }
+};
+
+// Given a current X position at the center Y position of a row, return the X
+// position of the left and right intercepts of the row top and bottom.
+template <typename E>
+static ALWAYS_INLINE FloatRange x_intercepts(const E& e) {
+ float rad = 0.5f * abs(e.x_slope());
+ return {e.cur_x() - rad, e.cur_x() + rad};
+}
+
+// Return the AA sub-span corresponding to a given edge. If AA is requested,
+// then this finds the X intercepts with the row clipped into range of the
+// edge and finally conservatively rounds them out. If there is no AA, then
+// it just returns the current rounded X position clipped within bounds.
+template <typename E>
+static ALWAYS_INLINE IntRange aa_edge(const E& e, const FloatRange& bounds) {
+ return e.edgeMask ? bounds.clip(x_intercepts(e)).round_out()
+ : bounds.clip({e.cur_x(), e.cur_x()}).round();
+}
+
+// Calculate the initial AA coverage as an approximation of the distance from
+// the center of the pixel in the direction of the edge slope. Given an edge
+// (x,y)..(x+dx,y+dy), then the normalized tangent vector along the edge is
+// (dx,dy)/sqrt(dx^2+dy^2). We know that for dy=1 then dx=e.x_slope. We rotate
+// the tangent vector either -90 or +90 degrees to get the edge normal vector,
+// where 'dx=-dy and 'dy=dx. Once normalized by 1/sqrt(dx^2+dy^2), scale into
+// the range of 0..256 so that we can cheaply convert to a fixed-point scale
+// factor. It is assumed that at exactly the pixel center the opacity is half
+// (128) and linearly decreases along the normal vector at 1:1 scale with the
+// slope. While not entirely accurate, this gives a reasonably agreeable looking
+// approximation of AA. For edges on which there is no AA, just force the
+// opacity to maximum (256) with no slope, relying on the span clipping to trim
+// pixels outside the span.
+template <typename E>
+static ALWAYS_INLINE FloatRange aa_dist(const E& e, float dir) {
+ if (e.edgeMask) {
+ float dx = (dir * 256.0f) * inversesqrt(1.0f + e.x_slope() * e.x_slope());
+ return {128.0f + dx * (e.cur_x() - 0.5f), -dx};
+ } else {
+ return {256.0f, 0.0f};
+ }
+}
+
+template <typename P, typename E>
+static ALWAYS_INLINE IntRange aa_span(P* buf, const E& left, const E& right,
+ const FloatRange& bounds) {
+ // If there is no AA, just return the span from the rounded left edge X
+ // position to the rounded right edge X position. Clip the span to be within
+ // the valid bounds.
+ if (!(swgl_ClipFlags & SWGL_CLIP_FLAG_AA)) {
+ return bounds.clip({left.cur_x(), right.cur_x()}).round();
+ }
+
+ // Calculate the left and right AA spans along with the coverage distances
+ // and slopes necessary to do blending.
+ IntRange leftAA = aa_edge(left, bounds);
+ FloatRange leftDist = aa_dist(left, -1.0f);
+ IntRange rightAA = aa_edge(right, bounds);
+ FloatRange rightDist = aa_dist(right, 1.0f);
+
+ // Use the pointer into the destination buffer as a status indicator of the
+ // coverage offset. The pointer is calculated so that subtracting it with
+ // the current destination pointer will yield a negative value if the span
+ // is outside the opaque area and otherwise will yield a positive value
+ // above the opaque size. This pointer is stored as a uint8 pointer so that
+ // there are no hidden multiplication instructions and will just return a
+ // 1:1 linear memory address. Thus the size of the opaque region must also
+ // be scaled by the pixel size in bytes.
+ swgl_OpaqueStart = (const uint8_t*)(buf + leftAA.end);
+ swgl_OpaqueSize = max(rightAA.start - leftAA.end - 3, 0) * sizeof(P);
+
+ // Offset the coverage distances by the end of the left AA span, which
+ // corresponds to the opaque start pointer, so that pixels become opaque
+ // immediately after. The distances are also offset for each lane in the
+ // chunk.
+ Float offset = cast(leftAA.end + (I32){0, 1, 2, 3});
+ swgl_LeftAADist = leftDist.start + offset * leftDist.end;
+ swgl_RightAADist = rightDist.start + offset * rightDist.end;
+ swgl_AASlope =
+ (Float){leftDist.end, rightDist.end, 0.0f, 0.0f} / float(sizeof(P));
+
+ // Return the full span width from the start of the left span to the end of
+ // the right span.
+ return {leftAA.start, rightAA.end};
+}
+
+// Calculate the span the user clip distances occupy from the left and right
+// edges at the current row.
+template <typename E>
+static ALWAYS_INLINE IntRange clip_distance_range(const E& left,
+ const E& right) {
+ Float leftClip = get_clip_distances(left.interp);
+ Float rightClip = get_clip_distances(right.interp);
+ // Get the change in clip dist per X step.
+ Float clipStep = (rightClip - leftClip) / (right.cur_x() - left.cur_x());
+ // Find the zero intercepts starting from the left edge.
+ Float clipDist =
+ clamp(left.cur_x() - leftClip * recip(clipStep), 0.0f, 1.0e6f);
+ // Find the distance to the start of the span for any clip distances that
+ // are increasing in value. If the clip distance is constant or decreasing
+ // in value, then check if it starts outside the clip volume.
+ Float start = if_then_else(clipStep > 0.0f, clipDist,
+ if_then_else(leftClip < 0.0f, 1.0e6f, 0.0f));
+ // Find the distance to the end of the span for any clip distances that are
+ // decreasing in value. If the clip distance is constant or increasing in
+ // value, then check if it ends inside the clip volume.
+ Float end = if_then_else(clipStep < 0.0f, clipDist,
+ if_then_else(rightClip >= 0.0f, 1.0e6f, 0.0f));
+ // Find the furthest start offset.
+ start = max(start, start.zwxy);
+ // Find the closest end offset.
+ end = min(end, end.zwxy);
+ // Finally, round the offsets to an integer span that can be used to bound
+ // the current span.
+ return FloatRange{max(start.x, start.y), min(end.x, end.y)}.round();
+}
+
+// Converts a run array into a flattened array of depth samples. This just
+// walks through every run and fills the samples with the depth value from
+// the run.
+static void flatten_depth_runs(DepthRun* runs, size_t width) {
+ if (runs->is_flat()) {
+ return;
+ }
+ while (width > 0) {
+ size_t n = runs->count;
+ fill_flat_depth(runs, n, runs->depth);
+ runs += n;
+ width -= n;
+ }
+}
+
+// Helper function for drawing passed depth runs within the depth buffer.
+// Flattened depth (perspective or discard) is not supported.
+template <typename P>
+static ALWAYS_INLINE void draw_depth_span(uint32_t z, P* buf,
+ DepthCursor& cursor) {
+ for (;;) {
+ // Get the span that passes the depth test. Assume on entry that
+ // any failed runs have already been skipped.
+ int span = cursor.check_passed(z, ctx->depthfunc, ctx->depthmask);
+ // If nothing passed, since we already skipped passed failed runs
+ // previously, we must have hit the end of the row. Bail out.
+ if (span <= 0) {
+ break;
+ }
+ if (span >= 4) {
+ // If we have a draw specialization, try to process as many 4-pixel
+ // chunks as possible using it.
+ if (fragment_shader->has_draw_span(buf)) {
+ int drawn = fragment_shader->draw_span(buf, span & ~3);
+ buf += drawn;
+ span -= drawn;
+ }
+ // Otherwise, just process each chunk individually.
+ while (span >= 4) {
+ fragment_shader->run();
+ discard_output<false>(buf);
+ buf += 4;
+ span -= 4;
+ }
+ }
+ // If we have a partial chunk left over, we still have to process it as if
+ // it were a full chunk. Mask off only the part of the chunk we want to
+ // use.
+ if (span > 0) {
+ fragment_shader->run();
+ discard_output<false>(buf, span);
+ buf += span;
+ }
+ // Skip past any runs that fail the depth test.
+ int skip = cursor.skip_failed(z, ctx->depthfunc);
+ // If there aren't any, that means we won't encounter any more passing runs
+ // and so it's safe to bail out.
+ if (skip <= 0) {
+ break;
+ }
+ // Advance interpolants for the fragment shader past the skipped region.
+ // If we processed a partial chunk above, we actually advanced the
+ // interpolants a full chunk in the fragment shader's run function. Thus,
+ // we need to first subtract off that 4-pixel chunk and only partially
+ // advance them to that partial chunk before we can add on the rest of the
+ // skips. This is combined with the skip here for efficiency's sake.
+ fragment_shader->skip(skip - (span > 0 ? 4 - span : 0));
+ buf += skip;
+ }
+}
+
+// Draw a simple span in 4-pixel wide chunks, optionally using depth.
+template <bool DISCARD, bool W, typename P, typename Z>
+static ALWAYS_INLINE void draw_span(P* buf, DepthRun* depth, int span, Z z) {
+ if (depth) {
+ // Depth testing is enabled. If perspective is used, Z values will vary
+ // across the span, we use packDepth to generate packed Z values suitable
+ // for depth testing based on current values from gl_FragCoord.z.
+ // Otherwise, for the no-perspective case, we just use the provided Z.
+ // Process 4-pixel chunks first.
+ for (; span >= 4; span -= 4, buf += 4, depth += 4) {
+ I32 zsrc = z();
+ ZMask zmask;
+ if (check_depth<DISCARD>(zsrc, depth, zmask)) {
+ fragment_shader->run<W>();
+ mask_output(buf, zmask);
+ if (DISCARD) discard_depth(zsrc, depth, zmask);
+ } else {
+ fragment_shader->skip<W>();
+ }
+ }
+ // If there are any remaining pixels, do a partial chunk.
+ if (span > 0) {
+ I32 zsrc = z();
+ ZMask zmask;
+ if (check_depth<DISCARD>(zsrc, depth, zmask, span)) {
+ fragment_shader->run<W>();
+ mask_output(buf, zmask, span);
+ if (DISCARD) discard_depth(zsrc, depth, zmask);
+ }
+ }
+ } else {
+ // Process 4-pixel chunks first.
+ for (; span >= 4; span -= 4, buf += 4) {
+ fragment_shader->run<W>();
+ discard_output<DISCARD>(buf);
+ }
+ // If there are any remaining pixels, do a partial chunk.
+ if (span > 0) {
+ fragment_shader->run<W>();
+ discard_output<DISCARD>(buf, span);
+ }
+ }
+}
+
+// Called during rasterization to forcefully clear a row on which delayed clear
+// has been enabled. If we know that we are going to completely overwrite a part
+// of the row, then we only need to clear the row outside of that part. However,
+// if blending or discard is enabled, the values of that underlying part of the
+// row may be used regardless to produce the final rasterization result, so we
+// have to then clear the entire underlying row to prepare it.
+template <typename P>
+static inline void prepare_row(Texture& colortex, int y, int startx, int endx,
+ bool use_discard, DepthRun* depth,
+ uint32_t z = 0, DepthCursor* cursor = nullptr) {
+ assert(colortex.delay_clear > 0);
+ // Delayed clear is enabled for the color buffer. Check if needs clear.
+ uint32_t& mask = colortex.cleared_rows[y / 32];
+ if ((mask & (1 << (y & 31))) == 0) {
+ mask |= 1 << (y & 31);
+ colortex.delay_clear--;
+ if (blend_key || use_discard) {
+ // If depth test, blending, or discard is used, old color values
+ // might be sampled, so we need to clear the entire row to fill it.
+ force_clear_row<P>(colortex, y);
+ } else if (depth) {
+ if (depth->is_flat() || !cursor) {
+ // If flat depth is used, we can't cheaply predict if which samples will
+ // pass.
+ force_clear_row<P>(colortex, y);
+ } else {
+ // Otherwise if depth runs are used, see how many samples initially pass
+ // the depth test and only fill the row outside those. The fragment
+ // shader will fill the row within the passed samples.
+ int passed =
+ DepthCursor(*cursor).check_passed<false>(z, ctx->depthfunc);
+ if (startx > 0 || startx + passed < colortex.width) {
+ force_clear_row<P>(colortex, y, startx, startx + passed);
+ }
+ }
+ } else if (startx > 0 || endx < colortex.width) {
+ // Otherwise, we only need to clear the row outside of the span.
+ // The fragment shader will fill the row within the span itself.
+ force_clear_row<P>(colortex, y, startx, endx);
+ }
+ }
+}
+
+// Perpendicular dot-product is the dot-product of a vector with the
+// perpendicular vector of the other, i.e. dot(a, {-b.y, b.x})
+template <typename T>
+static ALWAYS_INLINE auto perpDot(T a, T b) {
+ return a.x * b.y - a.y * b.x;
+}
+
+// Check if the winding of the initial edges is flipped, requiring us to swap
+// the edges to avoid spans having negative lengths. Assume that l0.y == r0.y
+// due to the initial edge scan in draw_quad/perspective_spans.
+template <typename T>
+static ALWAYS_INLINE bool checkIfEdgesFlipped(T l0, T l1, T r0, T r1) {
+ // If the starting point of the left edge is to the right of the starting
+ // point of the right edge, then just assume the edges are flipped. If the
+ // left and right starting points are the same, then check the sign of the
+ // cross-product of the edges to see if the edges are flipped. Otherwise,
+ // if the left starting point is actually just to the left of the right
+ // starting point, then assume no edge flip.
+ return l0.x > r0.x || (l0.x == r0.x && perpDot(l1 - l0, r1 - r0) > 0.0f);
+}
+
+// Draw spans for each row of a given quad (or triangle) with a constant Z
+// value. The quad is assumed convex. It is clipped to fall within the given
+// clip rect. In short, this function rasterizes a quad by first finding a
+// top most starting point and then from there tracing down the left and right
+// sides of this quad until it hits the bottom, outputting a span between the
+// current left and right positions at each row along the way. Points are
+// assumed to be ordered in either CW or CCW to support this, but currently
+// both orders (CW and CCW) are supported and equivalent.
+template <typename P>
+static inline void draw_quad_spans(int nump, Point2D p[4], uint32_t z,
+ Interpolants interp_outs[4],
+ Texture& colortex, Texture& depthtex,
+ const ClipRect& clipRect) {
+ // Only triangles and convex quads supported.
+ assert(nump == 3 || nump == 4);
+
+ Point2D l0, r0, l1, r1;
+ int l0i, r0i, l1i, r1i;
+ {
+ // Find the index of the top-most (smallest Y) point from which
+ // rasterization can start.
+ int top = nump > 3 && p[3].y < p[2].y
+ ? (p[0].y < p[1].y ? (p[0].y < p[3].y ? 0 : 3)
+ : (p[1].y < p[3].y ? 1 : 3))
+ : (p[0].y < p[1].y ? (p[0].y < p[2].y ? 0 : 2)
+ : (p[1].y < p[2].y ? 1 : 2));
+ // Helper to find next index in the points array, walking forward.
+#define NEXT_POINT(idx) \
+ ({ \
+ int cur = (idx) + 1; \
+ cur < nump ? cur : 0; \
+ })
+ // Helper to find the previous index in the points array, walking backward.
+#define PREV_POINT(idx) \
+ ({ \
+ int cur = (idx)-1; \
+ cur >= 0 ? cur : nump - 1; \
+ })
+ // Start looking for "left"-side and "right"-side descending edges starting
+ // from the determined top point.
+ int next = NEXT_POINT(top);
+ int prev = PREV_POINT(top);
+ if (p[top].y == p[next].y) {
+ // If the next point is on the same row as the top, then advance one more
+ // time to the next point and use that as the "left" descending edge.
+ l0i = next;
+ l1i = NEXT_POINT(next);
+ // Assume top and prev form a descending "right" edge, as otherwise this
+ // will be a collapsed polygon and harmlessly bail out down below.
+ r0i = top;
+ r1i = prev;
+ } else if (p[top].y == p[prev].y) {
+ // If the prev point is on the same row as the top, then advance to the
+ // prev again and use that as the "right" descending edge.
+ // Assume top and next form a non-empty descending "left" edge.
+ l0i = top;
+ l1i = next;
+ r0i = prev;
+ r1i = PREV_POINT(prev);
+ } else {
+ // Both next and prev are on distinct rows from top, so both "left" and
+ // "right" edges are non-empty/descending.
+ l0i = r0i = top;
+ l1i = next;
+ r1i = prev;
+ }
+ // Load the points from the indices.
+ l0 = p[l0i]; // Start of left edge
+ r0 = p[r0i]; // End of left edge
+ l1 = p[l1i]; // Start of right edge
+ r1 = p[r1i]; // End of right edge
+ // debugf("l0: %d(%f,%f), r0: %d(%f,%f) -> l1: %d(%f,%f), r1:
+ // %d(%f,%f)\n", l0i, l0.x, l0.y, r0i, r0.x, r0.y, l1i, l1.x, l1.y, r1i,
+ // r1.x, r1.y);
+ }
+
+ struct Edge {
+ float yScale;
+ float xSlope;
+ float x;
+ Interpolants interpSlope;
+ Interpolants interp;
+ bool edgeMask;
+
+ Edge(float y, const Point2D& p0, const Point2D& p1, const Interpolants& i0,
+ const Interpolants& i1, int edgeIndex)
+ : // Inverse Y scale for slope calculations. Avoid divide on 0-length
+ // edge. Later checks below ensure that Y <= p1.y, or otherwise we
+ // don't use this edge. We just need to guard against Y == p1.y ==
+ // p0.y. In that case, Y - p0.y == 0 and will cancel out the slopes
+ // below, except if yScale is Inf for some reason (or worse, NaN),
+ // which 1/(p1.y-p0.y) might produce if we don't bound it.
+ yScale(1.0f / max(p1.y - p0.y, 1.0f / 256)),
+ // Calculate dX/dY slope
+ xSlope((p1.x - p0.x) * yScale),
+ // Initialize current X based on Y and slope
+ x(p0.x + (y - p0.y) * xSlope),
+ // Calculate change in interpolants per change in Y
+ interpSlope((i1 - i0) * yScale),
+ // Initialize current interpolants based on Y and slope
+ interp(i0 + (y - p0.y) * interpSlope),
+ // Extract the edge mask status for this edge
+ edgeMask((swgl_AAEdgeMask >> edgeIndex) & 1) {}
+
+ void nextRow() {
+ // step current X and interpolants to next row from slope
+ x += xSlope;
+ interp += interpSlope;
+ }
+
+ float cur_x() const { return x; }
+ float x_slope() const { return xSlope; }
+ };
+
+ // Vertex selection above should result in equal left and right start rows
+ assert(l0.y == r0.y);
+ // Find the start y, clip to within the clip rect, and round to row center.
+ // If AA is enabled, round out conservatively rather than round to nearest.
+ float aaRound = swgl_ClipFlags & SWGL_CLIP_FLAG_AA ? 0.0f : 0.5f;
+ float y = floor(max(min(l0.y, clipRect.y1), clipRect.y0) + aaRound) + 0.5f;
+ // Initialize left and right edges from end points and start Y
+ Edge left(y, l0, l1, interp_outs[l0i], interp_outs[l1i], l1i);
+ Edge right(y, r0, r1, interp_outs[r0i], interp_outs[r1i], r0i);
+ // WR does not use backface culling, so check if edges are flipped.
+ bool flipped = checkIfEdgesFlipped(l0, l1, r0, r1);
+ if (flipped) swap(left, right);
+ // Get pointer to color buffer and depth buffer at current Y
+ P* fbuf = (P*)colortex.sample_ptr(0, int(y));
+ DepthRun* fdepth = depthtex.buf != nullptr
+ ? (DepthRun*)depthtex.sample_ptr(0, int(y))
+ : nullptr;
+ // Loop along advancing Ys, rasterizing spans at each row
+ float checkY = min(min(l1.y, r1.y), clipRect.y1);
+ // Ensure we don't rasterize out edge bounds
+ FloatRange clipSpan =
+ clipRect.x_range().clip(x_range(l0, l1).merge(x_range(r0, r1)));
+ for (;;) {
+ // Check if we maybe passed edge ends or outside clip rect...
+ if (y > checkY) {
+ // If we're outside the clip rect, we're done.
+ if (y > clipRect.y1) break;
+ // Helper to find the next non-duplicate vertex that doesn't loop back.
+#define STEP_EDGE(y, e0i, e0, e1i, e1, STEP_POINT, end) \
+ do { \
+ /* Set new start of edge to be end of old edge */ \
+ e0i = e1i; \
+ e0 = e1; \
+ /* Set new end of edge to next point */ \
+ e1i = STEP_POINT(e1i); \
+ e1 = p[e1i]; \
+ /* If the edge crossed the end, we're done. */ \
+ if (e0i == end) return; \
+ /* Otherwise, it doesn't advance, so keep searching. */ \
+ } while (y > e1.y)
+ // Check if Y advanced past the end of the left edge
+ if (y > l1.y) {
+ // Step to next left edge past Y and reset edge interpolants.
+ STEP_EDGE(y, l0i, l0, l1i, l1, NEXT_POINT, r1i);
+ (flipped ? right : left) =
+ Edge(y, l0, l1, interp_outs[l0i], interp_outs[l1i], l1i);
+ }
+ // Check if Y advanced past the end of the right edge
+ if (y > r1.y) {
+ // Step to next right edge past Y and reset edge interpolants.
+ STEP_EDGE(y, r0i, r0, r1i, r1, PREV_POINT, l1i);
+ (flipped ? left : right) =
+ Edge(y, r0, r1, interp_outs[r0i], interp_outs[r1i], r0i);
+ }
+ // Reset the clip bounds for the new edges
+ clipSpan =
+ clipRect.x_range().clip(x_range(l0, l1).merge(x_range(r0, r1)));
+ // Reset check condition for next time around.
+ checkY = min(ceil(min(l1.y, r1.y) - aaRound), clipRect.y1);
+ }
+
+ // Calculate a potentially AA'd span and check if it is non-empty.
+ IntRange span = aa_span(fbuf, left, right, clipSpan);
+ if (span.len() > 0) {
+ // If user clip planes are enabled, use them to bound the current span.
+ if (vertex_shader->use_clip_distance()) {
+ span = span.intersect(clip_distance_range(left, right));
+ if (span.len() <= 0) goto next_span;
+ }
+ ctx->shaded_rows++;
+ ctx->shaded_pixels += span.len();
+ // Advance color/depth buffer pointers to the start of the span.
+ P* buf = fbuf + span.start;
+ // Check if we will need to use depth-buffer or discard on this span.
+ DepthRun* depth =
+ depthtex.buf != nullptr && depthtex.cleared() ? fdepth : nullptr;
+ DepthCursor cursor;
+ bool use_discard = fragment_shader->use_discard();
+ if (use_discard) {
+ if (depth) {
+ // If we're using discard, we may have to unpredictably drop out some
+ // samples. Flatten the depth run array here to allow this.
+ if (!depth->is_flat()) {
+ flatten_depth_runs(depth, depthtex.width);
+ }
+ // Advance to the depth sample at the start of the span.
+ depth += span.start;
+ }
+ } else if (depth) {
+ if (!depth->is_flat()) {
+ // We're not using discard and the depth row is still organized into
+ // runs. Skip past any runs that would fail the depth test so we
+ // don't have to do any extra work to process them with the rest of
+ // the span.
+ cursor = DepthCursor(depth, depthtex.width, span.start, span.len());
+ int skipped = cursor.skip_failed(z, ctx->depthfunc);
+ // If we fell off the row, that means we couldn't find any passing
+ // runs. We can just skip the entire span.
+ if (skipped < 0) {
+ goto next_span;
+ }
+ buf += skipped;
+ span.start += skipped;
+ } else {
+ // The row is already flattened, so just advance to the span start.
+ depth += span.start;
+ }
+ }
+
+ if (colortex.delay_clear) {
+ // Delayed clear is enabled for the color buffer. Check if needs clear.
+ prepare_row<P>(colortex, int(y), span.start, span.end, use_discard,
+ depth, z, &cursor);
+ }
+
+ // Initialize fragment shader interpolants to current span position.
+ fragment_shader->gl_FragCoord.x = init_interp(span.start + 0.5f, 1);
+ fragment_shader->gl_FragCoord.y = y;
+ {
+ // Change in interpolants is difference between current right and left
+ // edges per the change in right and left X. If the left and right X
+ // positions are extremely close together, then avoid stepping the
+ // interpolants.
+ float stepScale = 1.0f / (right.x - left.x);
+ if (!isfinite(stepScale)) stepScale = 0.0f;
+ Interpolants step = (right.interp - left.interp) * stepScale;
+ // Advance current interpolants to X at start of span.
+ Interpolants o = left.interp + step * (span.start + 0.5f - left.x);
+ fragment_shader->init_span(&o, &step);
+ }
+ clipRect.set_clip_mask(span.start, y, buf);
+ if (!use_discard) {
+ // Fast paths for the case where fragment discard is not used.
+ if (depth) {
+ // If depth is used, we want to process entire depth runs if depth is
+ // not flattened.
+ if (!depth->is_flat()) {
+ draw_depth_span(z, buf, cursor);
+ goto next_span;
+ }
+ // Otherwise, flattened depth must fall back to the slightly slower
+ // per-chunk depth test path in draw_span below.
+ } else {
+ // Check if the fragment shader has an optimized draw specialization.
+ if (span.len() >= 4 && fragment_shader->has_draw_span(buf)) {
+ // Draw specialization expects 4-pixel chunks.
+ int drawn = fragment_shader->draw_span(buf, span.len() & ~3);
+ buf += drawn;
+ span.start += drawn;
+ }
+ }
+ draw_span<false, false>(buf, depth, span.len(), [=] { return z; });
+ } else {
+ // If discard is used, then use slower fallbacks. This should be rare.
+ // Just needs to work, doesn't need to be too fast yet...
+ draw_span<true, false>(buf, depth, span.len(), [=] { return z; });
+ }
+ }
+ next_span:
+ // Advance Y and edge interpolants to next row.
+ y++;
+ left.nextRow();
+ right.nextRow();
+ // Advance buffers to next row.
+ fbuf += colortex.stride() / sizeof(P);
+ fdepth += depthtex.stride() / sizeof(DepthRun);
+ }
+}
+
+// Draw perspective-correct spans for a convex quad that has been clipped to
+// the near and far Z planes, possibly producing a clipped convex polygon with
+// more than 4 sides. This assumes the Z value will vary across the spans and
+// requires interpolants to factor in W values. This tends to be slower than
+// the simpler 2D draw_quad_spans above, especially since we can't optimize the
+// depth test easily when Z values, and should be used only rarely if possible.
+template <typename P>
+static inline void draw_perspective_spans(int nump, Point3D* p,
+ Interpolants* interp_outs,
+ Texture& colortex, Texture& depthtex,
+ const ClipRect& clipRect) {
+ Point3D l0, r0, l1, r1;
+ int l0i, r0i, l1i, r1i;
+ {
+ // Find the index of the top-most point (smallest Y) from which
+ // rasterization can start.
+ int top = 0;
+ for (int i = 1; i < nump; i++) {
+ if (p[i].y < p[top].y) {
+ top = i;
+ }
+ }
+ // Find left-most top point, the start of the left descending edge.
+ // Advance forward in the points array, searching at most nump points
+ // in case the polygon is flat.
+ l0i = top;
+ for (int i = top + 1; i < nump && p[i].y == p[top].y; i++) {
+ l0i = i;
+ }
+ if (l0i == nump - 1) {
+ for (int i = 0; i <= top && p[i].y == p[top].y; i++) {
+ l0i = i;
+ }
+ }
+ // Find right-most top point, the start of the right descending edge.
+ // Advance backward in the points array, searching at most nump points.
+ r0i = top;
+ for (int i = top - 1; i >= 0 && p[i].y == p[top].y; i--) {
+ r0i = i;
+ }
+ if (r0i == 0) {
+ for (int i = nump - 1; i >= top && p[i].y == p[top].y; i--) {
+ r0i = i;
+ }
+ }
+ // End of left edge is next point after left edge start.
+ l1i = NEXT_POINT(l0i);
+ // End of right edge is prev point after right edge start.
+ r1i = PREV_POINT(r0i);
+ l0 = p[l0i]; // Start of left edge
+ r0 = p[r0i]; // End of left edge
+ l1 = p[l1i]; // Start of right edge
+ r1 = p[r1i]; // End of right edge
+ }
+
+ struct Edge {
+ float yScale;
+ // Current coordinates for edge. Where in the 2D case of draw_quad_spans,
+ // it is enough to just track the X coordinate as we advance along the rows,
+ // for the perspective case we also need to keep track of Z and W. For
+ // simplicity, we just use the full 3D point to track all these coordinates.
+ Point3D pSlope;
+ Point3D p;
+ Interpolants interpSlope;
+ Interpolants interp;
+ bool edgeMask;
+
+ Edge(float y, const Point3D& p0, const Point3D& p1, const Interpolants& i0,
+ const Interpolants& i1, int edgeIndex)
+ : // Inverse Y scale for slope calculations. Avoid divide on 0-length
+ // edge.
+ yScale(1.0f / max(p1.y - p0.y, 1.0f / 256)),
+ // Calculate dX/dY slope
+ pSlope((p1 - p0) * yScale),
+ // Initialize current coords based on Y and slope
+ p(p0 + (y - p0.y) * pSlope),
+ // Crucially, these interpolants must be scaled by the point's 1/w
+ // value, which allows linear interpolation in a perspective-correct
+ // manner. This will be canceled out inside the fragment shader later.
+ // Calculate change in interpolants per change in Y
+ interpSlope((i1 * p1.w - i0 * p0.w) * yScale),
+ // Initialize current interpolants based on Y and slope
+ interp(i0 * p0.w + (y - p0.y) * interpSlope),
+ // Extract the edge mask status for this edge
+ edgeMask((swgl_AAEdgeMask >> edgeIndex) & 1) {}
+
+ float x() const { return p.x; }
+ vec2_scalar zw() const { return {p.z, p.w}; }
+
+ void nextRow() {
+ // step current coords and interpolants to next row from slope
+ p += pSlope;
+ interp += interpSlope;
+ }
+
+ float cur_x() const { return p.x; }
+ float x_slope() const { return pSlope.x; }
+ };
+
+ // Vertex selection above should result in equal left and right start rows
+ assert(l0.y == r0.y);
+ // Find the start y, clip to within the clip rect, and round to row center.
+ // If AA is enabled, round out conservatively rather than round to nearest.
+ float aaRound = swgl_ClipFlags & SWGL_CLIP_FLAG_AA ? 0.0f : 0.5f;
+ float y = floor(max(min(l0.y, clipRect.y1), clipRect.y0) + aaRound) + 0.5f;
+ // Initialize left and right edges from end points and start Y
+ Edge left(y, l0, l1, interp_outs[l0i], interp_outs[l1i], l1i);
+ Edge right(y, r0, r1, interp_outs[r0i], interp_outs[r1i], r0i);
+ // WR does not use backface culling, so check if edges are flipped.
+ bool flipped = checkIfEdgesFlipped(l0, l1, r0, r1);
+ if (flipped) swap(left, right);
+ // Get pointer to color buffer and depth buffer at current Y
+ P* fbuf = (P*)colortex.sample_ptr(0, int(y));
+ DepthRun* fdepth = depthtex.buf != nullptr
+ ? (DepthRun*)depthtex.sample_ptr(0, int(y))
+ : nullptr;
+ // Loop along advancing Ys, rasterizing spans at each row
+ float checkY = min(min(l1.y, r1.y), clipRect.y1);
+ // Ensure we don't rasterize out edge bounds
+ FloatRange clipSpan =
+ clipRect.x_range().clip(x_range(l0, l1).merge(x_range(r0, r1)));
+ for (;;) {
+ // Check if we maybe passed edge ends or outside clip rect...
+ if (y > checkY) {
+ // If we're outside the clip rect, we're done.
+ if (y > clipRect.y1) break;
+ // Check if Y advanced past the end of the left edge
+ if (y > l1.y) {
+ // Step to next left edge past Y and reset edge interpolants.
+ STEP_EDGE(y, l0i, l0, l1i, l1, NEXT_POINT, r1i);
+ (flipped ? right : left) =
+ Edge(y, l0, l1, interp_outs[l0i], interp_outs[l1i], l1i);
+ }
+ // Check if Y advanced past the end of the right edge
+ if (y > r1.y) {
+ // Step to next right edge past Y and reset edge interpolants.
+ STEP_EDGE(y, r0i, r0, r1i, r1, PREV_POINT, l1i);
+ (flipped ? left : right) =
+ Edge(y, r0, r1, interp_outs[r0i], interp_outs[r1i], r0i);
+ }
+ // Reset the clip bounds for the new edges
+ clipSpan =
+ clipRect.x_range().clip(x_range(l0, l1).merge(x_range(r0, r1)));
+ // Reset check condition for next time around.
+ checkY = min(ceil(min(l1.y, r1.y) - aaRound), clipRect.y1);
+ }
+
+ // Calculate a potentially AA'd span and check if it is non-empty.
+ IntRange span = aa_span(fbuf, left, right, clipSpan);
+ if (span.len() > 0) {
+ // If user clip planes are enabled, use them to bound the current span.
+ if (vertex_shader->use_clip_distance()) {
+ span = span.intersect(clip_distance_range(left, right));
+ if (span.len() <= 0) goto next_span;
+ }
+ ctx->shaded_rows++;
+ ctx->shaded_pixels += span.len();
+ // Advance color/depth buffer pointers to the start of the span.
+ P* buf = fbuf + span.start;
+ // Check if the we will need to use depth-buffer or discard on this span.
+ DepthRun* depth =
+ depthtex.buf != nullptr && depthtex.cleared() ? fdepth : nullptr;
+ bool use_discard = fragment_shader->use_discard();
+ if (depth) {
+ // Perspective may cause the depth value to vary on a per sample basis.
+ // Ensure the depth row is flattened to allow testing of individual
+ // samples
+ if (!depth->is_flat()) {
+ flatten_depth_runs(depth, depthtex.width);
+ }
+ // Advance to the depth sample at the start of the span.
+ depth += span.start;
+ }
+ if (colortex.delay_clear) {
+ // Delayed clear is enabled for the color buffer. Check if needs clear.
+ prepare_row<P>(colortex, int(y), span.start, span.end, use_discard,
+ depth);
+ }
+ // Initialize fragment shader interpolants to current span position.
+ fragment_shader->gl_FragCoord.x = init_interp(span.start + 0.5f, 1);
+ fragment_shader->gl_FragCoord.y = y;
+ {
+ // Calculate the fragment Z and W change per change in fragment X step.
+ // If the left and right X positions are extremely close together, then
+ // avoid stepping.
+ float stepScale = 1.0f / (right.x() - left.x());
+ if (!isfinite(stepScale)) stepScale = 0.0f;
+ vec2_scalar stepZW = (right.zw() - left.zw()) * stepScale;
+ // Calculate initial Z and W values for span start.
+ vec2_scalar zw = left.zw() + stepZW * (span.start + 0.5f - left.x());
+ // Set fragment shader's Z and W values so that it can use them to
+ // cancel out the 1/w baked into the interpolants.
+ fragment_shader->gl_FragCoord.z = init_interp(zw.x, stepZW.x);
+ fragment_shader->gl_FragCoord.w = init_interp(zw.y, stepZW.y);
+ fragment_shader->swgl_StepZW = stepZW;
+ // Change in interpolants is difference between current right and left
+ // edges per the change in right and left X. The left and right
+ // interpolant values were previously multipled by 1/w, so the step and
+ // initial span values take this into account.
+ Interpolants step = (right.interp - left.interp) * stepScale;
+ // Advance current interpolants to X at start of span.
+ Interpolants o = left.interp + step * (span.start + 0.5f - left.x());
+ fragment_shader->init_span<true>(&o, &step);
+ }
+ clipRect.set_clip_mask(span.start, y, buf);
+ if (!use_discard) {
+ // No discard is used. Common case.
+ draw_span<false, true>(buf, depth, span.len(), packDepth);
+ } else {
+ // Discard is used. Rare.
+ draw_span<true, true>(buf, depth, span.len(), packDepth);
+ }
+ }
+ next_span:
+ // Advance Y and edge interpolants to next row.
+ y++;
+ left.nextRow();
+ right.nextRow();
+ // Advance buffers to next row.
+ fbuf += colortex.stride() / sizeof(P);
+ fdepth += depthtex.stride() / sizeof(DepthRun);
+ }
+}
+
+// Clip a primitive against both sides of a view-frustum axis, producing
+// intermediate vertexes with interpolated attributes that will no longer
+// intersect the selected axis planes. This assumes the primitive is convex
+// and should produce at most N+2 vertexes for each invocation (only in the
+// worst case where one point falls outside on each of the opposite sides
+// with the rest of the points inside). The supplied AA edge mask will be
+// modified such that it corresponds to the clipped polygon edges.
+template <XYZW AXIS>
+static int clip_side(int nump, Point3D* p, Interpolants* interp, Point3D* outP,
+ Interpolants* outInterp, int& outEdgeMask) {
+ // Potential mask bits of which side of a plane a coordinate falls on.
+ enum SIDE { POSITIVE = 1, NEGATIVE = 2 };
+ int numClip = 0;
+ int edgeMask = outEdgeMask;
+ Point3D prev = p[nump - 1];
+ Interpolants prevInterp = interp[nump - 1];
+ float prevCoord = prev.select(AXIS);
+ // Coordinate must satisfy -W <= C <= W. Determine if it is outside, and
+ // if so, remember which side it is outside of. In the special case that W is
+ // negative and |C| < |W|, both -W <= C and C <= W will be false, such that
+ // we must consider the coordinate as falling outside of both plane sides
+ // simultaneously. We test each condition separately and combine them to form
+ // a mask of which plane sides we exceeded. If we neglect to consider both
+ // sides simultaneously, points can erroneously oscillate from one plane side
+ // to the other and exceed the supported maximum number of clip outputs.
+ int prevMask = (prevCoord < -prev.w ? NEGATIVE : 0) |
+ (prevCoord > prev.w ? POSITIVE : 0);
+ // Loop through points, finding edges that cross the planes by evaluating
+ // the side at each point.
+ outEdgeMask = 0;
+ for (int i = 0; i < nump; i++, edgeMask >>= 1) {
+ Point3D cur = p[i];
+ Interpolants curInterp = interp[i];
+ float curCoord = cur.select(AXIS);
+ int curMask =
+ (curCoord < -cur.w ? NEGATIVE : 0) | (curCoord > cur.w ? POSITIVE : 0);
+ // Check if the previous and current end points are on different sides. If
+ // the masks of sides intersect, then we consider them to be on the same
+ // side. So in the case the masks do not intersect, we then consider them
+ // to fall on different sides.
+ if (!(curMask & prevMask)) {
+ // One of the edge's end points is outside the plane with the other
+ // inside the plane. Find the offset where it crosses the plane and
+ // adjust the point and interpolants to there.
+ if (prevMask) {
+ // Edge that was previously outside crosses inside.
+ // Evaluate plane equation for previous and current end-point
+ // based on previous side and calculate relative offset.
+ if (numClip >= nump + 2) {
+ // If for some reason we produced more vertexes than we support, just
+ // bail out.
+ assert(false);
+ return 0;
+ }
+ // The positive plane is assigned the sign 1, and the negative plane is
+ // assigned -1. If the point falls outside both planes, that means W is
+ // negative. To compensate for this, we must interpolate the coordinate
+ // till W=0, at which point we can choose a single plane side for the
+ // coordinate to fall on since W will no longer be negative. To compute
+ // the coordinate where W=0, we compute K = prev.w / (prev.w-cur.w) and
+ // interpolate C = prev.C + K*(cur.C - prev.C). The sign of C will be
+ // the side of the plane we need to consider. Substituting K into the
+ // comparison C < 0, we can then avoid the division in K with a
+ // cross-multiplication.
+ float prevSide =
+ (prevMask & NEGATIVE) && (!(prevMask & POSITIVE) ||
+ prevCoord * (cur.w - prev.w) <
+ prev.w * (curCoord - prevCoord))
+ ? -1
+ : 1;
+ float prevDist = prevCoord - prevSide * prev.w;
+ float curDist = curCoord - prevSide * cur.w;
+ // It may happen that after we interpolate by the weight k that due to
+ // floating point rounding we've underestimated the value necessary to
+ // push it over the clipping boundary. Just in case, nudge the mantissa
+ // by a single increment so that we essentially round it up and move it
+ // further inside the clipping boundary. We use nextafter to do this in
+ // a portable fashion.
+ float k = prevDist / (prevDist - curDist);
+ Point3D clipped = prev + (cur - prev) * k;
+ if (prevSide * clipped.select(AXIS) > clipped.w) {
+ k = nextafterf(k, 1.0f);
+ clipped = prev + (cur - prev) * k;
+ }
+ outP[numClip] = clipped;
+ outInterp[numClip] = prevInterp + (curInterp - prevInterp) * k;
+ // Don't output the current edge mask since start point was outside.
+ numClip++;
+ }
+ if (curMask) {
+ // Edge that was previously inside crosses outside.
+ // Evaluate plane equation for previous and current end-point
+ // based on current side and calculate relative offset.
+ if (numClip >= nump + 2) {
+ assert(false);
+ return 0;
+ }
+ // In the case the coordinate falls on both plane sides, the computation
+ // here is much the same as for prevSide, but since we are going from a
+ // previous W that is positive to current W that is negative, then the
+ // sign of cur.w - prev.w will flip in the equation. The resulting sign
+ // is negated to compensate for this.
+ float curSide =
+ (curMask & POSITIVE) && (!(curMask & NEGATIVE) ||
+ prevCoord * (cur.w - prev.w) <
+ prev.w * (curCoord - prevCoord))
+ ? 1
+ : -1;
+ float prevDist = prevCoord - curSide * prev.w;
+ float curDist = curCoord - curSide * cur.w;
+ // Calculate interpolation weight k and the nudge it inside clipping
+ // boundary with nextafter. Note that since we were previously inside
+ // and now crossing outside, we have to flip the nudge direction for
+ // the weight towards 0 instead of 1.
+ float k = prevDist / (prevDist - curDist);
+ Point3D clipped = prev + (cur - prev) * k;
+ if (curSide * clipped.select(AXIS) > clipped.w) {
+ k = nextafterf(k, 0.0f);
+ clipped = prev + (cur - prev) * k;
+ }
+ outP[numClip] = clipped;
+ outInterp[numClip] = prevInterp + (curInterp - prevInterp) * k;
+ // Output the current edge mask since the end point is inside.
+ outEdgeMask |= (edgeMask & 1) << numClip;
+ numClip++;
+ }
+ }
+ if (!curMask) {
+ // The current end point is inside the plane, so output point unmodified.
+ if (numClip >= nump + 2) {
+ assert(false);
+ return 0;
+ }
+ outP[numClip] = cur;
+ outInterp[numClip] = curInterp;
+ // Output the current edge mask since the end point is inside.
+ outEdgeMask |= (edgeMask & 1) << numClip;
+ numClip++;
+ }
+ prev = cur;
+ prevInterp = curInterp;
+ prevCoord = curCoord;
+ prevMask = curMask;
+ }
+ return numClip;
+}
+
+// Helper function to dispatch to perspective span drawing with points that
+// have already been transformed and clipped.
+static inline void draw_perspective_clipped(int nump, Point3D* p_clip,
+ Interpolants* interp_clip,
+ Texture& colortex,
+ Texture& depthtex) {
+ // If polygon is ouside clip rect, nothing to draw.
+ ClipRect clipRect(colortex);
+ if (!clipRect.overlaps(nump, p_clip)) {
+ return;
+ }
+
+ // Finally draw perspective-correct spans for the polygon.
+ if (colortex.internal_format == GL_RGBA8) {
+ draw_perspective_spans<uint32_t>(nump, p_clip, interp_clip, colortex,
+ depthtex, clipRect);
+ } else if (colortex.internal_format == GL_R8) {
+ draw_perspective_spans<uint8_t>(nump, p_clip, interp_clip, colortex,
+ depthtex, clipRect);
+ } else {
+ assert(false);
+ }
+}
+
+// Draws a perspective-correct 3D primitive with varying Z value, as opposed
+// to a simple 2D planar primitive with a constant Z value that could be
+// trivially Z rejected. This requires clipping the primitive against the near
+// and far planes to ensure it stays within the valid Z-buffer range. The Z
+// and W of each fragment of the primitives are interpolated across the
+// generated spans and then depth-tested as appropriate.
+// Additionally, vertex attributes must be interpolated with perspective-
+// correction by dividing by W before interpolation, and then later multiplied
+// by W again to produce the final correct attribute value for each fragment.
+// This process is expensive and should be avoided if possible for primitive
+// batches that are known ahead of time to not need perspective-correction.
+static void draw_perspective(int nump, Interpolants interp_outs[4],
+ Texture& colortex, Texture& depthtex) {
+ // Lines are not supported with perspective.
+ assert(nump >= 3);
+ // Convert output of vertex shader to screen space.
+ vec4 pos = vertex_shader->gl_Position;
+ vec3_scalar scale =
+ vec3_scalar(ctx->viewport.width(), ctx->viewport.height(), 1) * 0.5f;
+ vec3_scalar offset =
+ make_vec3(make_vec2(ctx->viewport.origin() - colortex.offset), 0.0f) +
+ scale;
+ // Verify if point is between near and far planes, rejecting NaN.
+ if (test_all(pos.z > -pos.w && pos.z < pos.w)) {
+ // No points cross the near or far planes, so no clipping required.
+ // Just divide coords by W and convert to viewport. We assume the W
+ // coordinate is non-zero and the reciprocal is finite since it would
+ // otherwise fail the test_none condition.
+ Float w = 1.0f / pos.w;
+ vec3 screen = pos.sel(X, Y, Z) * w * scale + offset;
+ Point3D p[4] = {{screen.x.x, screen.y.x, screen.z.x, w.x},
+ {screen.x.y, screen.y.y, screen.z.y, w.y},
+ {screen.x.z, screen.y.z, screen.z.z, w.z},
+ {screen.x.w, screen.y.w, screen.z.w, w.w}};
+ draw_perspective_clipped(nump, p, interp_outs, colortex, depthtex);
+ } else {
+ // Points cross the near or far planes, so we need to clip.
+ // Start with the original 3 or 4 points...
+ Point3D p[4] = {{pos.x.x, pos.y.x, pos.z.x, pos.w.x},
+ {pos.x.y, pos.y.y, pos.z.y, pos.w.y},
+ {pos.x.z, pos.y.z, pos.z.z, pos.w.z},
+ {pos.x.w, pos.y.w, pos.z.w, pos.w.w}};
+ // Clipping can expand the points by 1 for each of 6 view frustum planes.
+ Point3D p_clip[4 + 6];
+ Interpolants interp_clip[4 + 6];
+ // Clip against near and far Z planes.
+ nump = clip_side<Z>(nump, p, interp_outs, p_clip, interp_clip,
+ swgl_AAEdgeMask);
+ // If no points are left inside the view frustum, there's nothing to draw.
+ if (nump < 3) {
+ return;
+ }
+ // After clipping against only the near and far planes, we might still
+ // produce points where W = 0, exactly at the camera plane. OpenGL specifies
+ // that for clip coordinates, points must satisfy:
+ // -W <= X <= W
+ // -W <= Y <= W
+ // -W <= Z <= W
+ // When Z = W = 0, this is trivially satisfied, but when we transform and
+ // divide by W below it will produce a divide by 0. Usually we want to only
+ // clip Z to avoid the extra work of clipping X and Y. We can still project
+ // points that fall outside the view frustum X and Y so long as Z is valid.
+ // The span drawing code will then ensure X and Y are clamped to viewport
+ // boundaries. However, in the Z = W = 0 case, sometimes clipping X and Y,
+ // will push W further inside the view frustum so that it is no longer 0,
+ // allowing us to finally proceed to projecting the points to the screen.
+ for (int i = 0; i < nump; i++) {
+ // Found an invalid W, so need to clip against X and Y...
+ if (p_clip[i].w <= 0.0f) {
+ // Ping-pong p_clip -> p_tmp -> p_clip.
+ Point3D p_tmp[4 + 6];
+ Interpolants interp_tmp[4 + 6];
+ nump = clip_side<X>(nump, p_clip, interp_clip, p_tmp, interp_tmp,
+ swgl_AAEdgeMask);
+ if (nump < 3) return;
+ nump = clip_side<Y>(nump, p_tmp, interp_tmp, p_clip, interp_clip,
+ swgl_AAEdgeMask);
+ if (nump < 3) return;
+ // After clipping against X and Y planes, there's still points left
+ // to draw, so proceed to trying projection now...
+ break;
+ }
+ }
+ // Divide coords by W and convert to viewport.
+ for (int i = 0; i < nump; i++) {
+ float w = 1.0f / p_clip[i].w;
+ // If the W coord is essentially zero, small enough that division would
+ // result in Inf/NaN, then just set the point to all zeroes, as the only
+ // point that satisfies -W <= X/Y/Z <= W is all zeroes.
+ p_clip[i] = isfinite(w)
+ ? Point3D(p_clip[i].sel(X, Y, Z) * w * scale + offset, w)
+ : Point3D(0.0f);
+ }
+ draw_perspective_clipped(nump, p_clip, interp_clip, colortex, depthtex);
+ }
+}
+
+static void draw_quad(int nump, Texture& colortex, Texture& depthtex) {
+ // Run vertex shader once for the primitive's vertices.
+ // Reserve space for 6 sets of interpolants, in case we need to clip against
+ // near and far planes in the perspective case.
+ Interpolants interp_outs[4];
+ swgl_ClipFlags = 0;
+ vertex_shader->run_primitive((char*)interp_outs, sizeof(Interpolants));
+ vec4 pos = vertex_shader->gl_Position;
+ // Check if any vertex W is different from another. If so, use perspective.
+ if (test_any(pos.w != pos.w.x)) {
+ draw_perspective(nump, interp_outs, colortex, depthtex);
+ return;
+ }
+
+ // Convert output of vertex shader to screen space.
+ // Divide coords by W and convert to viewport.
+ float w = 1.0f / pos.w.x;
+ // If the W coord is essentially zero, small enough that division would
+ // result in Inf/NaN, then just set the reciprocal itself to zero so that
+ // the coordinates becomes zeroed out, as the only valid point that
+ // satisfies -W <= X/Y/Z <= W is all zeroes.
+ if (!isfinite(w)) w = 0.0f;
+ vec2 screen = (pos.sel(X, Y) * w + 1) * 0.5f *
+ vec2_scalar(ctx->viewport.width(), ctx->viewport.height()) +
+ make_vec2(ctx->viewport.origin() - colortex.offset);
+ Point2D p[4] = {{screen.x.x, screen.y.x},
+ {screen.x.y, screen.y.y},
+ {screen.x.z, screen.y.z},
+ {screen.x.w, screen.y.w}};
+
+ // If quad is ouside clip rect, nothing to draw.
+ ClipRect clipRect(colortex);
+ if (!clipRect.overlaps(nump, p)) {
+ return;
+ }
+
+ // Since the quad is assumed 2D, Z is constant across the quad.
+ float screenZ = (pos.z.x * w + 1) * 0.5f;
+ if (screenZ < 0 || screenZ > 1) {
+ // Z values would cross the near or far plane, so just bail.
+ return;
+ }
+ // Since Z doesn't need to be interpolated, just set the fragment shader's
+ // Z and W values here, once and for all fragment shader invocations.
+ uint32_t z = uint32_t(MAX_DEPTH_VALUE * screenZ);
+ fragment_shader->gl_FragCoord.z = screenZ;
+ fragment_shader->gl_FragCoord.w = w;
+
+ // If supplied a line, adjust it so that it is a quad at least 1 pixel thick.
+ // Assume that for a line that all 4 SIMD lanes were actually filled with
+ // vertexes 0, 1, 1, 0.
+ if (nump == 2) {
+ // Nudge Y height to span at least 1 pixel by advancing to next pixel
+ // boundary so that we step at least 1 row when drawing spans.
+ if (int(p[0].y + 0.5f) == int(p[1].y + 0.5f)) {
+ p[2].y = 1 + int(p[1].y + 0.5f);
+ p[3].y = p[2].y;
+ // Nudge X width to span at least 1 pixel so that rounded coords fall on
+ // separate pixels.
+ if (int(p[0].x + 0.5f) == int(p[1].x + 0.5f)) {
+ p[1].x += 1.0f;
+ p[2].x += 1.0f;
+ }
+ } else {
+ // If the line already spans at least 1 row, then assume line is vertical
+ // or diagonal and just needs to be dilated horizontally.
+ p[2].x += 1.0f;
+ p[3].x += 1.0f;
+ }
+ // Pretend that it's a quad now...
+ nump = 4;
+ }
+
+ // Finally draw 2D spans for the quad. Currently only supports drawing to
+ // RGBA8 and R8 color buffers.
+ if (colortex.internal_format == GL_RGBA8) {
+ draw_quad_spans<uint32_t>(nump, p, z, interp_outs, colortex, depthtex,
+ clipRect);
+ } else if (colortex.internal_format == GL_R8) {
+ draw_quad_spans<uint8_t>(nump, p, z, interp_outs, colortex, depthtex,
+ clipRect);
+ } else {
+ assert(false);
+ }
+}
+
+template <typename INDEX>
+static inline void draw_elements(GLsizei count, GLsizei instancecount,
+ size_t offset, VertexArray& v,
+ Texture& colortex, Texture& depthtex) {
+ Buffer& indices_buf = ctx->buffers[v.element_array_buffer_binding];
+ if (!indices_buf.buf || offset >= indices_buf.size) {
+ return;
+ }
+ assert((offset & (sizeof(INDEX) - 1)) == 0);
+ INDEX* indices = (INDEX*)(indices_buf.buf + offset);
+ count = min(count, (GLsizei)((indices_buf.size - offset) / sizeof(INDEX)));
+ // Triangles must be indexed at offsets 0, 1, 2.
+ // Quads must be successive triangles indexed at offsets 0, 1, 2, 2, 1, 3.
+ if (count == 6 && indices[1] == indices[0] + 1 &&
+ indices[2] == indices[0] + 2 && indices[5] == indices[0] + 3) {
+ assert(indices[3] == indices[0] + 2 && indices[4] == indices[0] + 1);
+ // Fast path - since there is only a single quad, we only load per-vertex
+ // attribs once for all instances, as they won't change across instances
+ // or within an instance.
+ vertex_shader->load_attribs(v.attribs, indices[0], 0, 4);
+ draw_quad(4, colortex, depthtex);
+ for (GLsizei instance = 1; instance < instancecount; instance++) {
+ vertex_shader->load_attribs(v.attribs, indices[0], instance, 0);
+ draw_quad(4, colortex, depthtex);
+ }
+ } else {
+ for (GLsizei instance = 0; instance < instancecount; instance++) {
+ for (GLsizei i = 0; i + 3 <= count; i += 3) {
+ if (indices[i + 1] != indices[i] + 1 ||
+ indices[i + 2] != indices[i] + 2) {
+ continue;
+ }
+ if (i + 6 <= count && indices[i + 5] == indices[i] + 3) {
+ assert(indices[i + 3] == indices[i] + 2 &&
+ indices[i + 4] == indices[i] + 1);
+ vertex_shader->load_attribs(v.attribs, indices[i], instance, 4);
+ draw_quad(4, colortex, depthtex);
+ i += 3;
+ } else {
+ vertex_shader->load_attribs(v.attribs, indices[i], instance, 3);
+ draw_quad(3, colortex, depthtex);
+ }
+ }
+ }
+ }
+}