Fix: CNN v2 compute shader validation error

Replace textureSample() with textureSampleLevel() in compute shader.
textureSample() requires derivative calculations only available in fragment
shaders. Compute shaders must explicitly specify mip level.

Fixes: DemoEffectsTest CNNv2Effect initialization

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/workspaces/main/shaders/cnn_v2/cnn_v2_static.wgsl b/workspaces/main/shaders/cnn_v2/cnn_v2_static.wgsl
index 63fafa8..309e832 100644
--- a/workspaces/main/shaders/cnn_v2/cnn_v2_static.wgsl
+++ b/workspaces/main/shaders/cnn_v2/cnn_v2_static.wgsl
@@ -33,17 +33,18 @@ fn main(@builtin(global_invocation_id) id: vec3<u32>) {
 
   // Parametric features (p0-p3) - bilinear sample from specified mip level
   // Use UV coordinates for bilinear interpolation
+  // Note: Use textureSampleLevel (not textureSample) in compute shaders
   let uv = (vec2<f32>(coord) + 0.5) / vec2<f32>(dims);
   var rgba: vec4<f32>;
   if (params.mip_level == 0u) {
-    rgba = textureSample(input_tex, linear_sampler, uv);
+    rgba = textureSampleLevel(input_tex, linear_sampler, uv, 0.0);
   } else if (params.mip_level == 1u) {
-    rgba = textureSample(input_tex_mip1, linear_sampler, uv);
+    rgba = textureSampleLevel(input_tex_mip1, linear_sampler, uv, 0.0);
   } else if (params.mip_level == 2u) {
-    rgba = textureSample(input_tex_mip2, linear_sampler, uv);
+    rgba = textureSampleLevel(input_tex_mip2, linear_sampler, uv, 0.0);
   } else {
     // Mip 3 or higher: use mip 2 as fallback
-    rgba = textureSample(input_tex_mip2, linear_sampler, uv);
+    rgba = textureSampleLevel(input_tex_mip2, linear_sampler, uv, 0.0);
   }
 
   let p0 = rgba.r;