Compute vertex position for image shader

1 files changed, 5 insertions, 3 deletions

diff --git a/wgpu/src/shader/image.wgsl b/wgpu/src/shader/image.wgsl
index 5e22cdf4..0c8b3bdb 100644
--- a/wgpu/src/shader/image.wgsl
+++ b/wgpu/src/shader/image.wgsl
@@ -7,7 +7,7 @@ struct Globals {
 @group(1) @binding(0) var u_texture: texture_2d_array<f32>;
 
 struct VertexInput {
-    @location(0) v_pos: vec2<f32>,
+    @builtin(vertex_index) vertex_index: u32,
     @location(1) pos: vec2<f32>,
     @location(2) scale: vec2<f32>,
     @location(3) atlas_pos: vec2<f32>,
@@ -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;
 }