| adapter.rs |
|
52354 |
| command.rs |
|
44946 |
| conv.rs |
|
19403 |
| device.rs |
|
63071 |
| egl.rs |
|
55400 |
| emscripten.rs |
|
979 |
| mod.rs |
!
# OpenGL ES3 API (aka GLES3).
Designed to work on Linux and Android, with context provided by EGL.
## Texture views
GLES3 doesn't really have separate texture view objects. We have to remember the
original texture and the sub-range into it. Problem is, however, that there is
no way to expose a subset of array layers or mip levels of a sampled texture.
## Binding model
Binding model is very different from WebGPU, especially with regards to samplers.
GLES3 has sampler objects, but they aren't separately bindable to the shaders.
Each sampled texture is exposed to the shader as a combined texture-sampler binding.
When building the pipeline layout, we linearize binding entries based on the groups
(uniform/storage buffers, uniform/storage textures), and record the mapping into
`BindGroupLayoutInfo`.
When a pipeline gets created, and we track all the texture-sampler associations
from the static use in the shader.
We only support at most one sampler used with each texture so far. The linear index
of this sampler is stored per texture slot in `SamplerBindMap` array.
The texture-sampler pairs get potentially invalidated in 2 places:
- when a new pipeline is set, we update the linear indices of associated samplers
- when a new bind group is set, we update both the textures and the samplers
We expect that the changes to sampler states between any 2 pipelines of the same layout
will be minimal, if any.
## Vertex data
Generally, vertex buffers are marked as dirty and lazily bound on draw.
GLES3 doesn't support `first_instance` semantics. However, it's easy to support,
since we are forced to do late binding anyway. We just adjust the offsets
into the vertex data.
### Old path
In GLES-3.0 and WebGL2, vertex buffer layout is provided
together with the actual buffer binding.
We invalidate the attributes on the vertex buffer change, and re-bind them.
### New path
In GLES-3.1 and higher, the vertex buffer layout can be declared separately
from the vertex data itself. This mostly matches WebGPU, however there is a catch:
`stride` needs to be specified with the data, not as a part of the layout.
To address this, we invalidate the vertex buffers based on:
- whether or not `first_instance` is used
- stride has changed
## Handling of `base_vertex`, `first_instance`, and `first_vertex`
Between indirect, the lack of `first_instance` semantics, and the availability of `gl_BaseInstance`
in shaders, getting buffers and builtins to work correctly is a bit tricky.
We never emulate `base_vertex` and gl_VertexID behaves as `@builtin(vertex_index)` does, so we
never need to do anything about that.
We always advertise support for `VERTEX_AND_INSTANCE_INDEX_RESPECTS_RESPECTIVE_FIRST_VALUE_IN_INDIRECT_DRAW`.
### GL 4.2+ with ARB_shader_draw_parameters
- `@builtin(instance_index)` translates to `gl_InstanceID + gl_BaseInstance`
- We bind instance buffers without any offset emulation.
- We advertise support for the `INDIRECT_FIRST_INSTANCE` feature.
While we can theoretically have a card with 4.2+ support but without ARB_shader_draw_parameters,
we don't bother with that combination.
### GLES & GL 4.1
- `@builtin(instance_index)` translates to `gl_InstanceID + naga_vs_first_instance`
- We bind instance buffers with offset emulation.
- We _do not_ advertise support for `INDIRECT_FIRST_INSTANCE` and cpu-side pretend the `first_instance` is 0 on indirect calls.
|
32078 |
| queue.rs |
|
84318 |
| shaders |
|
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| web.rs |
|
16331 |
| wgl.rs |
|
29372 |