2cdca4441a
This removes some calls to commit_span from inside the draw_span specializers. Instead it relies upon the span rasterizer loop to do some of the work, which will incur a function pointer call in the rare case we actually return out of a specializer early. This shouldn't be that performance critical and will remove some inliner bloat. Also, I refactored commit_output in the rasterizer itself to hopefully cause fewer template instantiations which should also further reduce inliner bloat. Differential Revision: https://phabricator.services.mozilla.com/D104150 |
||
|---|---|---|
| .. | ||
| src | ||
| Cargo.toml | ||
| README.md | ||
| build.rs | ||
README.md
swgl
Software OpenGL implementation for WebRender
Overview
This is a relatively simple single threaded software rasterizer designed for use by WebRender. It will shade one quad at a time using a 4xf32 vector with one vertex per lane. It rasterizes quads usings spans and shades that span 4 pixels at a time.
Building
clang-cl is required to build on Windows. This can be done by installing
the llvm binaries from https://releases.llvm.org/ and adding the installation
to the path with something like set PATH=%PATH%;C:\Program Files\LLVM\bin.
Then set CC=clang-cl and set CXX=clang-cl. That should be sufficient
for cc-rs to use clang-cl instead of cl.
Extensions
SWGL contains a number of OpenGL and GLSL extensions designed to both ease integration with WebRender and to help accelerate span rasterization.
GLSL extension intrinsics are generally prefixed with swgl_ to distinguish
them from other items in the GLSL namespace.
Inside GLSL, the SWGL preprocessor token is defined so that usage of SWGL
extensions may be conditionally compiled.
void swgl_clipMask(sampler2D mask, vec2 offset, vec2 bb_origin, vec2 bb_size);
When called from the the vertex shader, this specifies a clip mask texture to be used to mask the currently drawn primitive while blending is enabled. This mask will only apply to the current primitive.
The mask must be an R8 texture that will be interpreted as alpha weighting applied to the source pixel prior to the blend stage. It is sampled 1:1 with nearest filtering without any applied transform. The given offset specifies the positioning of the clip mask relative to the framebuffer's viewport.
The supplied bounding box constrains sampling of the clip mask to only fall within the given rectangle, specified relative to the clip mask offset. Anything falling outside this rectangle will be clipped entirely. If the rectangle is empty, then the clip mask will be ignored.