Fix textures not getting added to WebGPU shaders

Author: davepagurek

src/webgpu/p5.RendererWebGPU.js

@@ -2254,6 +2254,9 @@ function rendererWebGPU(p5, fn) {
       // Inject hook uniforms as a separate struct at a new binding
       let hookUniformFields = '';
       for (const key in shader.hooks.uniforms) {
+        // Skip textures, they don't get added to structs
+        if (key.endsWith(': sampler2D')) continue;
+
         // WGSL format: "name: type"
         hookUniformFields += `  ${key},\n`;
       }

src/webgpu/strands_wgslBackend.js

@@ -223,10 +223,11 @@ export const wgslBackend = {
     return primitiveTypeName;
   },
   generateHookUniformKey(name, typeInfo) {
-    // For sampler2D types, we don't add them to the uniform struct
-    // Instead, they become separate texture and sampler bindings
+    // For sampler2D types, we don't add them to the uniform struct,
+    // but we still need them in the shader's hooks object so that
+    // they can be set by users.
     if (typeInfo.baseType === 'sampler2D') {
-      return null; // Signal that this should not be added to uniform struct
+      return `${name}: sampler2D`; // Signal that this should not be added to uniform struct
     }
     return `${name}: ${this.getTypeName(typeInfo.baseType, typeInfo.dimension)}`;
   },