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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/. */
+
+/// # Brush vertex shaders memory layout
+///
+/// The overall memory layout is the same for all brush shaders.
+///
+/// The vertex shader receives a minimal amount of data from vertex attributes (packed into a single
+/// ivec4 per instance) and the rest is fetched from various uniform samplers using offsets decoded
+/// from the vertex attributes.
+///
+/// The diagram below shows the the various pieces of data fectched in the vertex shader:
+///
+///```ascii
+/// (sPrimitiveHeadersI)
+/// (VBO) +-----------------------+
+/// +----------------------------+ +----------------------------> | Int header |
+/// | Instance vertex attributes | | (sPrimitiveHeadersF) | |
+/// | | | +---------------------+ | z |
+/// | x: prim_header_address +-------+---> | Float header | | specific_address +-----+
+/// | y: picture_task_address +---------+ | | | transform_address +---+ |
+/// | clip_address +-----+ | | local_rect | | user_data | | |
+/// | z: flags | | | | local_clip_rect | +-----------------------+ | |
+/// | segment_index | | | +---------------------+ | |
+/// | w: resource_address +--+ | | | |
+/// +----------------------------+ | | | (sGpuCache) | |
+/// | | | (sGpuCache) +------------+ | |
+/// | | | +---------------+ | Transform | <--------+ |
+/// (sGpuCache) | | +-> | Picture task | +------------+ |
+/// +-------------+ | | | | |
+/// | Resource | <---+ | | ... | |
+/// | | | +---------------+ +--------------------------------+
+/// | | | |
+/// +-------------+ | (sGpuCache) v (sGpuCache)
+/// | +---------------+ +--------------+---------------+-+-+
+/// +-----> | Clip area | | Brush data | Segment data | | |
+/// | | | | | | |
+/// | ... | | ... | ... | | | ...
+/// +---------------+ +--------------+---------------+-+-+
+///```
+///
+/// - Segment data address is obtained by combining the address stored in the int header and the
+/// segment index decoded from the vertex attributes.
+/// - Resource data is optional, some brush types (such as images) store some extra data there while
+/// other brush types don't use it.
+///
+
+#if (defined(WR_FEATURE_ALPHA_PASS) || defined(WR_FEATURE_ANTIALIASING)) && !defined(SWGL_ANTIALIAS)
+varying highp vec2 v_local_pos;
+#endif
+
+#ifdef WR_VERTEX_SHADER
+
+void brush_vs(
+ VertexInfo vi,
+ int prim_address,
+ RectWithEndpoint local_rect,
+ RectWithEndpoint segment_rect,
+ ivec4 prim_user_data,
+ int specific_resource_address,
+ mat4 transform,
+ PictureTask pic_task,
+ int brush_flags,
+ vec4 segment_data
+);
+
+// Forward-declare the text vertex shader entry point which is currently
+// different from other brushes.
+void text_shader_main(
+ Instance instance,
+ PrimitiveHeader ph,
+ Transform transform,
+ PictureTask task,
+ ClipArea clip_area
+);
+
+#define VECS_PER_SEGMENT 2
+
+#define BRUSH_FLAG_PERSPECTIVE_INTERPOLATION 1
+#define BRUSH_FLAG_SEGMENT_RELATIVE 2
+#define BRUSH_FLAG_SEGMENT_REPEAT_X 4
+#define BRUSH_FLAG_SEGMENT_REPEAT_Y 8
+#define BRUSH_FLAG_SEGMENT_REPEAT_X_ROUND 16
+#define BRUSH_FLAG_SEGMENT_REPEAT_Y_ROUND 32
+#define BRUSH_FLAG_SEGMENT_NINEPATCH_MIDDLE 64
+#define BRUSH_FLAG_TEXEL_RECT 128
+#define BRUSH_FLAG_FORCE_AA 256
+
+#define INVALID_SEGMENT_INDEX 0xffff
+
+void brush_shader_main_vs(
+ Instance instance,
+ PrimitiveHeader ph,
+ Transform transform,
+ PictureTask pic_task,
+ ClipArea clip_area
+) {
+ int edge_flags = (instance.flags >> 12) & 0xf;
+ int brush_flags = instance.flags & 0xfff;
+
+ // Fetch the segment of this brush primitive we are drawing.
+ vec4 segment_data;
+ RectWithEndpoint segment_rect;
+ if (instance.segment_index == INVALID_SEGMENT_INDEX) {
+ segment_rect = ph.local_rect;
+ segment_data = vec4(0.0);
+ } else {
+ int segment_address = ph.specific_prim_address +
+ VECS_PER_SPECIFIC_BRUSH +
+ instance.segment_index * VECS_PER_SEGMENT;
+
+ vec4[2] segment_info = fetch_from_gpu_cache_2(segment_address);
+ segment_rect = RectWithEndpoint(segment_info[0].xy, segment_info[0].zw);
+ segment_rect.p0 += ph.local_rect.p0;
+ segment_rect.p1 += ph.local_rect.p0;
+ segment_data = segment_info[1];
+ }
+
+ // Most of the time this is the segment rect, but when doing the edge AA
+ // it is inflated.
+ RectWithEndpoint adjusted_segment_rect = segment_rect;
+
+ bool antialiased = !transform.is_axis_aligned || ((brush_flags & BRUSH_FLAG_FORCE_AA) != 0);
+
+ // Write the normal vertex information out.
+ if (antialiased) {
+ adjusted_segment_rect = clip_and_init_antialiasing(
+ segment_rect,
+ ph.local_rect,
+ ph.local_clip_rect,
+ edge_flags,
+ ph.z,
+ transform,
+ pic_task
+ );
+
+ // The clip was taken into account in clip_and_init_antialiasing, remove
+ // it so that it doesn't interfere with the aa.
+ ph.local_clip_rect.p0 = vec2(-1.0e16);
+ ph.local_clip_rect.p1 = vec2(1.0e16);
+ } else {
+ // The common case for most CSS content.
+
+ // TODO(gw): transform bounds may be referenced by
+ // the fragment shader when running in
+ // the alpha pass, even on non-transformed
+ // items. For now, just ensure it has no
+ // effect. We can tidy this up as we move
+ // more items to be brush shaders.
+#if defined(WR_FEATURE_ALPHA_PASS) && !defined(SWGL_ANTIALIAS)
+ init_transform_vs(vec4(vec2(-1.0e16), vec2(1.0e16)));
+#endif
+ }
+
+ // Select the corner of the local rect that we are processing.
+ vec2 local_pos = mix(adjusted_segment_rect.p0, adjusted_segment_rect.p1, aPosition.xy);
+
+ VertexInfo vi = write_vertex(
+ local_pos,
+ ph.local_clip_rect,
+ ph.z,
+ transform,
+ pic_task
+ );
+
+ // For brush instances in the alpha pass, always write
+ // out clip information.
+ // TODO(gw): It's possible that we might want alpha
+ // shaders that don't clip in the future,
+ // but it's reasonable to assume that one
+ // implies the other, for now.
+ // SW-WR may decay some requests for alpha-pass shaders to
+ // the opaque version if only the clip-mask is required. In
+ // that case the opaque vertex shader must still write out
+ // the clip information, which is cheap to do for SWGL.
+#if defined(WR_FEATURE_ALPHA_PASS) || defined(SWGL_CLIP_MASK)
+ write_clip(
+ vi.world_pos,
+ clip_area,
+ pic_task
+ );
+#endif
+
+ // Run the specific brush VS code to write interpolators.
+ brush_vs(
+ vi,
+ ph.specific_prim_address,
+ ph.local_rect,
+ segment_rect,
+ ph.user_data,
+ instance.resource_address,
+ transform.m,
+ pic_task,
+ brush_flags,
+ segment_data
+ );
+
+#if (defined(WR_FEATURE_ALPHA_PASS) || defined(WR_FEATURE_ANTIALIASING)) && !defined(SWGL_ANTIALIAS)
+ v_local_pos = vi.local_pos;
+#endif
+}
+
+#ifndef WR_VERTEX_SHADER_MAIN_FUNCTION
+// If the entry-point was not overridden before including the brush shader,
+// use the default one.
+#define WR_VERTEX_SHADER_MAIN_FUNCTION brush_shader_main_vs
+#endif
+
+void main(void) {
+
+ Instance instance = decode_instance_attributes();
+ PrimitiveHeader ph = fetch_prim_header(instance.prim_header_address);
+ Transform transform = fetch_transform(ph.transform_id);
+ PictureTask task = fetch_picture_task(instance.picture_task_address);
+ ClipArea clip_area = fetch_clip_area(instance.clip_address);
+
+ WR_VERTEX_SHADER_MAIN_FUNCTION(instance, ph, transform, task, clip_area);
+}
+
+#endif // WR_VERTEX_SHADER
+
+#ifdef WR_FRAGMENT_SHADER
+
+float antialias_brush() {
+#if (defined(WR_FEATURE_ALPHA_PASS) || defined(WR_FEATURE_ANTIALIASING)) && !defined(SWGL_ANTIALIAS)
+ return init_transform_fs(v_local_pos);
+#else
+ return 1.0;
+#endif
+}
+
+Fragment brush_fs();
+
+void main(void) {
+#ifdef WR_FEATURE_DEBUG_OVERDRAW
+ oFragColor = WR_DEBUG_OVERDRAW_COLOR;
+#else
+
+ Fragment frag = brush_fs();
+
+#ifdef WR_FEATURE_ALPHA_PASS
+ // Apply the clip mask
+ float clip_alpha = do_clip();
+
+ frag.color *= clip_alpha;
+
+ #ifdef WR_FEATURE_DUAL_SOURCE_BLENDING
+ oFragBlend = frag.blend * clip_alpha;
+ #endif
+#endif
+
+ write_output(frag.color);
+#endif
+}
+#endif