Separate shader hooks into dedicated functions to avoid name collisions/shadowing

Author: mrxz

examples/debug-color/index.html

@@ -64,10 +64,12 @@
             }
             return quatVec(quaternion, normal);
           }
+
+          vec3 objectNormal;
         `,
         objectModifier: /*glsl*/`
           // Determine normal in object space
-          vec3 objectNormal = gsplatNormal(scales, quaternion);
+          objectNormal = gsplatNormal(scales, quaternion);
         `,
         splatColor: /*glsl*/`
           // Transform normal into world space

src/Splat.ts

@@ -429,7 +429,12 @@ export class Splat extends THREE.Mesh<SplatGeometry, THREE.ShaderMaterial> {
 
     // Prepare compile hook
     this.material.onBeforeCompile = (program, renderer) => {
+      if (!program.defines) {
+        program.defines = {};
+      }
+
       if (this.shaderHooks?.vertex) {
+        program.defines.HOOK_UNIFORMS = !!this.shaderHooks.vertex.uniforms;
         if (this.shaderHooks.vertex.uniforms) {
           // Generate uniform code block
           const uniforms = Object.entries(this.shaderHooks.vertex.uniforms)
@@ -439,24 +444,30 @@ export class Splat extends THREE.Mesh<SplatGeometry, THREE.ShaderMaterial> {
             )
             .join("\n");
           program.vertexShader = program.vertexShader.replace(
-            "#define HOOK_UNIFORMS",
+            "{{HOOK_UNIFORMS}}",
             uniforms,
           );
         }
+        program.defines.HOOK_GLOBAL = !!this.shaderHooks.vertex.global;
         program.vertexShader = program.vertexShader.replace(
-          "#define HOOK_GLOBAL",
+          "{{HOOK_GLOBAL}}",
           this.shaderHooks.vertex.global ?? "",
         );
+        program.defines.HOOK_OBJECT_MODIFIER =
+          !!this.shaderHooks.vertex.objectModifier;
         program.vertexShader = program.vertexShader.replace(
-          "#define HOOK_OBJECT_MODIFIER",
+          "{{HOOK_OBJECT_MODIFIER}}",
           this.shaderHooks.vertex.objectModifier ?? "",
         );
+        program.defines.HOOK_WORLD_MODIFIER =
+          !!this.shaderHooks.vertex.worldModifier;
         program.vertexShader = program.vertexShader.replace(
-          "#define HOOK_WORLD_MODIFIER",
+          "{{HOOK_WORLD_MODIFIER}}",
           this.shaderHooks.vertex.worldModifier ?? "",
         );
+        program.defines.HOOK_SPLAT_COLOR = !!this.shaderHooks.vertex.splatColor;
         program.vertexShader = program.vertexShader.replace(
-          "#define HOOK_SPLAT_COLOR",
+          "{{HOOK_SPLAT_COLOR}}",
           this.shaderHooks.vertex.splatColor ?? "",
         );
       }

src/shaders/splatVertex.glsl

@@ -50,9 +50,34 @@ uniform float preBlurAmount;
 uniform float clipXY;
 uniform float focalAdjustment;
 
-#define HOOK_GLOBAL
+// Shader hooks
+#ifdef HOOK_GLOBAL
+{{HOOK_GLOBAL}}
+#endif
+
+#ifdef HOOK_UNIFORMS
+{{HOOK_UNIFORMS}}
+#endif
+
+#ifdef HOOK_OBJECT_MODIFIER
+void _shader_hook_object_modifier(inout vec3 center, inout vec3 scales, inout vec4 quaternion, inout vec4 rgba) {
+    {{HOOK_OBJECT_MODIFIER}}
+}
+#endif
+
+#ifdef HOOK_WORLD_MODIFIER
+void _shader_hook_world_modifier(inout vec3 center, inout vec3 scales, inout vec4 quaternion, inout vec4 rgba) {
+    {{HOOK_WORLD_MODIFIER}}
+}
+#endif
+
+#ifdef HOOK_SPLAT_COLOR
+vec4 _shader_hook_splat_color(in vec3 center, in vec3 scales, in vec4 quaternion, inout vec4 rgba, in vec3 viewCenter) {
+    {{HOOK_SPLAT_COLOR}}
+    return rgba;
+}
+#endif
 
-#define HOOK_UNIFORMS
 
 void main() {
     // Default to outside the frustum so it's discarded if we return early
@@ -68,7 +93,9 @@ void main() {
     uint sIndex = splatIndex & 0x3FFFFFu;
     uint objectIndex = splatIndex >> 26u;
     decodeSplat(sIndex, center, scales, quaternion, rgba);
-    #define HOOK_OBJECT_MODIFIER
+#ifdef HOOK_OBJECT_MODIFIER
+    _shader_hook_object_modifier(center, scales, quaternion, rgba);
+#endif
 
 #ifdef USE_BATCHING
     mat4 splatModelMatrix = getBatchingMatrix(objectIndex);
@@ -86,7 +113,10 @@ void main() {
     center = (splatModelMatrix * vec4(center, 1.0)).xyz;
     scales *= modelScale;
     rgba.a *= opacity;
-    #define HOOK_WORLD_MODIFIER
+
+#ifdef HOOK_WORLD_MODIFIER
+    _shader_hook_world_modifier(center, scales, quaternion, rgba);
+#endif
 
     if (rgba.a < minAlpha) {
         return;
@@ -224,7 +254,9 @@ void main() {
     rgba.rgb += evaluateSH(viewDir, sh1, sh2, sh3);
     #endif
 
-    #define HOOK_SPLAT_COLOR
+#ifdef HOOK_SPLAT_COLOR
+    rgba = _shader_hook_splat_color(center, scales, quaternion, rgba, viewCenter);
+#endif
 
     vRgba = rgba;
     vSplatUv = position.xy * maxStdDev;