Merge pull request #2099 from jim-ec/master

Compute vertex positions in the shader

4 files changed, 37 insertions, 28 deletions

diff --git a/wgpu/src/shader/image.wgsl b/wgpu/src/shader/image.wgsl
index 5e22cdf4..7b2e5238 100644
--- a/wgpu/src/shader/image.wgsl
+++ b/wgpu/src/shader/image.wgsl
@@ -7,12 +7,12 @@ struct Globals {
 @group(1) @binding(0) var u_texture: texture_2d_array<f32>;
 
 struct VertexInput {
-    @location(0) v_pos: vec2<f32>,
-    @location(1) pos: vec2<f32>,
-    @location(2) scale: vec2<f32>,
-    @location(3) atlas_pos: vec2<f32>,
-    @location(4) atlas_scale: vec2<f32>,
-    @location(5) layer: i32,
+    @builtin(vertex_index) vertex_index: u32,
+    @location(0) pos: vec2<f32>,
+    @location(1) scale: vec2<f32>,
+    @location(2) atlas_pos: vec2<f32>,
+    @location(3) atlas_scale: vec2<f32>,
+    @location(4) layer: i32,
 }
 
 struct VertexOutput {
@@ -25,7 +25,9 @@ struct VertexOutput {
 fn vs_main(input: VertexInput) -> VertexOutput {
     var out: VertexOutput;
 
-    out.uv = vec2<f32>(input.v_pos * input.atlas_scale + input.atlas_pos);
+    let v_pos = vertex_position(input.vertex_index);
+
+    out.uv = vec2<f32>(v_pos * input.atlas_scale + input.atlas_pos);
     out.layer = f32(input.layer);
 
     var transform: mat4x4<f32> = mat4x4<f32>(
@@ -35,7 +37,7 @@ fn vs_main(input: VertexInput) -> VertexOutput {
         vec4<f32>(input.pos, 0.0, 1.0)
     );
 
-    out.position = globals.transform * transform * vec4<f32>(input.v_pos, 0.0, 1.0);
+    out.position = globals.transform * transform * vec4<f32>(v_pos, 0.0, 1.0);
 
     return out;
 }
diff --git a/wgpu/src/shader/quad/gradient.wgsl b/wgpu/src/shader/quad/gradient.wgsl
index 0754e97f..4ad2fea8 100644
--- a/wgpu/src/shader/quad/gradient.wgsl
+++ b/wgpu/src/shader/quad/gradient.wgsl
@@ -1,15 +1,15 @@
 struct GradientVertexInput {
-    @location(0) v_pos: vec2<f32>,
-    @location(1) @interpolate(flat) colors_1: vec4<u32>,
-    @location(2) @interpolate(flat) colors_2: vec4<u32>,
-    @location(3) @interpolate(flat) colors_3: vec4<u32>,
-    @location(4) @interpolate(flat) colors_4: vec4<u32>,
-    @location(5) @interpolate(flat) offsets: vec4<u32>,
-    @location(6) direction: vec4<f32>,
-    @location(7) position_and_scale: vec4<f32>,
-    @location(8) border_color: vec4<f32>,
-    @location(9) border_radius: vec4<f32>,
-    @location(10) border_width: f32,
+    @builtin(vertex_index) vertex_index: u32,
+    @location(0) @interpolate(flat) colors_1: vec4<u32>,
+    @location(1) @interpolate(flat) colors_2: vec4<u32>,
+    @location(2) @interpolate(flat) colors_3: vec4<u32>,
+    @location(3) @interpolate(flat) colors_4: vec4<u32>,
+    @location(4) @interpolate(flat) offsets: vec4<u32>,
+    @location(5) direction: vec4<f32>,
+    @location(6) position_and_scale: vec4<f32>,
+    @location(7) border_color: vec4<f32>,
+    @location(8) border_radius: vec4<f32>,
+    @location(9) border_width: f32,
 }
 
 struct GradientVertexOutput {
@@ -48,7 +48,7 @@ fn gradient_vs_main(input: GradientVertexInput) -> GradientVertexOutput {
         vec4<f32>(pos - vec2<f32>(0.5, 0.5), 0.0, 1.0)
     );
 
-    out.position = globals.transform * transform * vec4<f32>(input.v_pos, 0.0, 1.0);
+    out.position = globals.transform * transform * vec4<f32>(vertex_position(input.vertex_index), 0.0, 1.0);
     out.colors_1 = input.colors_1;
     out.colors_2 = input.colors_2;
     out.colors_3 = input.colors_3;
diff --git a/wgpu/src/shader/quad/solid.wgsl b/wgpu/src/shader/quad/solid.wgsl
index ebd6d877..f84dd7ab 100644
--- a/wgpu/src/shader/quad/solid.wgsl
+++ b/wgpu/src/shader/quad/solid.wgsl
@@ -1,11 +1,11 @@
 struct SolidVertexInput {
-    @location(0) v_pos: vec2<f32>,
-    @location(1) color: vec4<f32>,
-    @location(2) pos: vec2<f32>,
-    @location(3) scale: vec2<f32>,
-    @location(4) border_color: vec4<f32>,
-    @location(5) border_radius: vec4<f32>,
-    @location(6) border_width: f32,
+    @builtin(vertex_index) vertex_index: u32,
+    @location(0) color: vec4<f32>,
+    @location(1) pos: vec2<f32>,
+    @location(2) scale: vec2<f32>,
+    @location(3) border_color: vec4<f32>,
+    @location(4) border_radius: vec4<f32>,
+    @location(5) border_width: f32,
 }
 
 struct SolidVertexOutput {
@@ -40,7 +40,7 @@ fn solid_vs_main(input: SolidVertexInput) -> SolidVertexOutput {
         vec4<f32>(pos - vec2<f32>(0.5, 0.5), 0.0, 1.0)
     );
 
-    out.position = globals.transform * transform * vec4<f32>(input.v_pos, 0.0, 1.0);
+    out.position = globals.transform * transform * vec4<f32>(vertex_position(input.vertex_index), 0.0, 1.0);
     out.color = input.color;
     out.border_color = input.border_color;
     out.pos = pos;
diff --git a/wgpu/src/shader/vertex.wgsl b/wgpu/src/shader/vertex.wgsl
new file mode 100644
index 00000000..e6af6fc0
--- /dev/null
+++ b/wgpu/src/shader/vertex.wgsl
@@ -0,0 +1,7 @@
+// Compute the normalized quad coordinates based on the vertex index.
+fn vertex_position(vertex_index: u32) -> vec2<f32> {
+    // #: 0 1 2 3 4 5
+    // x: 1 1 0 0 0 1
+    // y: 1 0 0 0 1 1
+    return vec2<f32>((vec2(1u, 2u) + vertex_index) % vec2(6u) < vec2(3u));
+}