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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.
///
#ifdef WR_VERTEX_SHADER
void brush_vs(
VertexInfo vi,
int prim_address,
RectWithSize local_rect,
RectWithSize 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 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 & 0xff;
int brush_flags = (instance.flags >> 8) & 0xff;
// Fetch the segment of this brush primitive we are drawing.
vec4 segment_data;
RectWithSize 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 = RectWithSize(segment_info[0].xy, segment_info[0].zw);
segment_rect.p0 += ph.local_rect.p0;
segment_data = segment_info[1];
}
VertexInfo vi;
// Write the normal vertex information out.
if (transform.is_axis_aligned) {
// Select the corner of the local rect that we are processing.
vec2 local_pos = segment_rect.p0 + segment_rect.size * aPosition.xy;
vi = write_vertex(
local_pos,
ph.local_clip_rect,
ph.z,
transform,
pic_task
);
// 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.
#ifdef WR_FEATURE_ALPHA_PASS
init_transform_vs(vec4(vec2(-1.0e16), vec2(1.0e16)));
#endif
} else {
bvec4 edge_mask = notEqual(edge_flags & ivec4(1, 2, 4, 8), ivec4(0));
vi = write_transform_vertex(
segment_rect,
ph.local_rect,
ph.local_clip_rect,
mix(vec4(0.0), vec4(1.0), edge_mask),
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.
#ifdef WR_FEATURE_ALPHA_PASS
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
);
}
#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
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
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