webgpu: Add a webgpu_traits crate (#36320)

This breaks the `script_traits` dependency  on `webgpu`. In general, the
`traits` crates shouldn't depend on Servo non-`traits` crates. This is
necessary to move "script to constellation" messages to the
`constellation_traits` crate, making it the entire API for talking to
the
constellation. This will break a circular dependency when that happens.

Testing: Successfully building is enough of a test for this one as
it is mainly moving types around.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/shared/webgpu/render_commands.rs

@@ -0,0 +1,155 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+//! Render pass commands
+
+use serde::{Deserialize, Serialize};
+use wgpu_core::command::{RenderPass, RenderPassError};
+use wgpu_core::global::Global;
+use wgpu_core::id::{BindGroupId, BufferId, RenderBundleId, RenderPipelineId};
+
+/// <https://github.com/gfx-rs/wgpu/blob/f25e07b984ab391628d9568296d5970981d79d8b/wgpu-core/src/command/render_command.rs#L17>
+#[derive(Debug, Deserialize, Serialize)]
+pub enum RenderCommand {
+    SetPipeline(RenderPipelineId),
+    SetBindGroup {
+        index: u32,
+        bind_group_id: BindGroupId,
+        offsets: Vec<u32>,
+    },
+    SetViewport {
+        x: f32,
+        y: f32,
+        width: f32,
+        height: f32,
+        min_depth: f32,
+        max_depth: f32,
+    },
+    SetScissorRect {
+        x: u32,
+        y: u32,
+        width: u32,
+        height: u32,
+    },
+    SetBlendConstant(wgpu_types::Color),
+    SetStencilReference(u32),
+    SetIndexBuffer {
+        buffer_id: BufferId,
+        index_format: wgpu_types::IndexFormat,
+        offset: u64,
+        size: Option<wgpu_types::BufferSize>,
+    },
+    SetVertexBuffer {
+        slot: u32,
+        buffer_id: BufferId,
+        offset: u64,
+        size: Option<wgpu_types::BufferSize>,
+    },
+    Draw {
+        vertex_count: u32,
+        instance_count: u32,
+        first_vertex: u32,
+        first_instance: u32,
+    },
+    DrawIndexed {
+        index_count: u32,
+        instance_count: u32,
+        first_index: u32,
+        base_vertex: i32,
+        first_instance: u32,
+    },
+    DrawIndirect {
+        buffer_id: BufferId,
+        offset: u64,
+    },
+    DrawIndexedIndirect {
+        buffer_id: BufferId,
+        offset: u64,
+    },
+    ExecuteBundles(Vec<RenderBundleId>),
+}
+
+pub fn apply_render_command(
+    global: &Global,
+    pass: &mut RenderPass,
+    command: RenderCommand,
+) -> Result<(), RenderPassError> {
+    match command {
+        RenderCommand::SetPipeline(pipeline_id) => {
+            global.render_pass_set_pipeline(pass, pipeline_id)
+        },
+        RenderCommand::SetBindGroup {
+            index,
+            bind_group_id,
+            offsets,
+        } => global.render_pass_set_bind_group(pass, index, Some(bind_group_id), &offsets),
+        RenderCommand::SetViewport {
+            x,
+            y,
+            width,
+            height,
+            min_depth,
+            max_depth,
+        } => global.render_pass_set_viewport(pass, x, y, width, height, min_depth, max_depth),
+        RenderCommand::SetScissorRect {
+            x,
+            y,
+            width,
+            height,
+        } => global.render_pass_set_scissor_rect(pass, x, y, width, height),
+        RenderCommand::SetBlendConstant(color) => {
+            global.render_pass_set_blend_constant(pass, color)
+        },
+        RenderCommand::SetStencilReference(reference) => {
+            global.render_pass_set_stencil_reference(pass, reference)
+        },
+        RenderCommand::SetIndexBuffer {
+            buffer_id,
+            index_format,
+            offset,
+            size,
+        } => global.render_pass_set_index_buffer(pass, buffer_id, index_format, offset, size),
+        RenderCommand::SetVertexBuffer {
+            slot,
+            buffer_id,
+            offset,
+            size,
+        } => global.render_pass_set_vertex_buffer(pass, slot, buffer_id, offset, size),
+        RenderCommand::Draw {
+            vertex_count,
+            instance_count,
+            first_vertex,
+            first_instance,
+        } => global.render_pass_draw(
+            pass,
+            vertex_count,
+            instance_count,
+            first_vertex,
+            first_instance,
+        ),
+        RenderCommand::DrawIndexed {
+            index_count,
+            instance_count,
+            first_index,
+            base_vertex,
+            first_instance,
+        } => global.render_pass_draw_indexed(
+            pass,
+            index_count,
+            instance_count,
+            first_index,
+            base_vertex,
+            first_instance,
+        ),
+        RenderCommand::DrawIndirect { buffer_id, offset } => {
+            global.render_pass_draw_indirect(pass, buffer_id, offset)
+        },
+        RenderCommand::DrawIndexedIndirect { buffer_id, offset } => {
+            global.render_pass_draw_indexed_indirect(pass, buffer_id, offset)
+        },
+        RenderCommand::ExecuteBundles(bundles) => {
+            global.render_pass_execute_bundles(pass, &bundles)
+        },
+    }
+}