Add a hook to be able to change the final shader code before being compiled

src/Materials/PBR/pbrBaseMaterial.ts

@@ -21,7 +21,7 @@ import { Scalar } from "../../Maths/math.scalar";
 
 import { ImageProcessingConfiguration, IImageProcessingConfigurationDefines } from "../../Materials/imageProcessingConfiguration";
 import { Effect, IEffectCreationOptions } from "../../Materials/effect";
-import { Material, IMaterialCompilationOptions } from "../../Materials/material";
+import { Material, IMaterialCompilationOptions, ICustomShaderNameResolveOptions } from "../../Materials/material";
 import { MaterialDefines } from "../../Materials/materialDefines";
 import { PushMaterial } from "../../Materials/pushMaterial";
 import { MaterialHelper } from "../../Materials/materialHelper";
@@ -664,7 +664,6 @@ export abstract class PBRBaseMaterial extends PushMaterial {
         this.markAsDirty(Constants.MATERIAL_TextureDirtyFlag);
     }
 
-
     /**
      * Force normal to face away from face.
      */
@@ -1258,8 +1257,10 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             maxSimultaneousLights: this._maxSimultaneousLights
         });
 
+        const csnrOptions: ICustomShaderNameResolveOptions = {};
+
         if (this.customShaderNameResolve) {
-            shaderName = this.customShaderNameResolve(shaderName, uniforms, uniformBuffers, samplers, defines, attribs);
+            shaderName = this.customShaderNameResolve(shaderName, uniforms, uniformBuffers, samplers, defines, attribs, csnrOptions);
         }
 
         var join = defines.toString();
@@ -1272,7 +1273,8 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             fallbacks: fallbacks,
             onCompiled: onCompiled,
             onError: onError,
-            indexParameters: { maxSimultaneousLights: this._maxSimultaneousLights, maxSimultaneousMorphTargets: defines.NUM_MORPH_INFLUENCERS }
+            indexParameters: { maxSimultaneousLights: this._maxSimultaneousLights, maxSimultaneousMorphTargets: defines.NUM_MORPH_INFLUENCERS },
+            processFinalCode: csnrOptions.processFinalCode,
         }, engine);
     }
 

src/Materials/effect.ts

@@ -65,6 +65,10 @@ export interface IEffectCreationOptions {
      * See https://developer.mozilla.org/en-US/docs/Web/API/WebGL2RenderingContext/transformFeedbackVaryings
      */
     transformFeedbackVaryings?: Nullable<string[]>;
+    /**
+     * If provided, will be called two times with the vertex and fragment code so that this code can be updated before it is compiled by the GPU
+     */
+    processFinalCode?: Nullable<(shaderType: string, code: string) => string>;
 }
 
 /**
@@ -189,6 +193,8 @@ export class Effect implements IDisposable {
         fallbacks: Nullable<IEffectFallbacks> = null, onCompiled: Nullable<(effect: Effect) => void> = null, onError: Nullable<(effect: Effect, errors: string) => void> = null, indexParameters?: any) {
         this.name = baseName;
 
+        let processFinalCode: Nullable<(shaderType: string, code: string) => string> = null;
+
         if ((<IEffectCreationOptions>attributesNamesOrOptions).attributes) {
             var options = <IEffectCreationOptions>attributesNamesOrOptions;
             this._engine = <Engine>uniformsNamesOrEngine;
@@ -209,6 +215,8 @@ export class Effect implements IDisposable {
                     this._uniformBuffersNames[options.uniformBuffersNames[i]] = i;
                 }
             }
+
+            processFinalCode = options.processFinalCode ?? null;
         } else {
             this._engine = <Engine>engine;
             this.defines = (defines == null ? "" : defines);
@@ -273,8 +281,14 @@ export class Effect implements IDisposable {
         this._loadShader(vertexSource, "Vertex", "", (vertexCode) => {
             this._loadShader(fragmentSource, "Fragment", "Pixel", (fragmentCode) => {
                 ShaderProcessor.Process(vertexCode, processorOptions, (migratedVertexCode) => {
+                    if (processFinalCode) {
+                        migratedVertexCode = processFinalCode("vertex", migratedVertexCode);
+                    }
                     processorOptions.isFragment = true;
                     ShaderProcessor.Process(fragmentCode, processorOptions, (migratedFragmentCode) => {
+                        if (processFinalCode) {
+                            migratedFragmentCode = processFinalCode("fragment", migratedFragmentCode);
+                        }
                         this._useFinalCode(migratedVertexCode, migratedFragmentCode, baseName);
                     });
                 });

src/Materials/material.ts

@@ -43,6 +43,16 @@ export interface IMaterialCompilationOptions {
 }
 
 /**
+ * Options passed when calling customShaderNameResolve
+ */
+export interface ICustomShaderNameResolveOptions {
+    /**
+     * If provided, will be called two times with the vertex and fragment code so that this code can be updated before it is compiled by the GPU
+     */
+    processFinalCode?: Nullable<(shaderType: string, code: string) => string>;
+}
+
+/**
  * Base class for the main features of a material in Babylon.js
  */
 export class Material implements IAnimatable {
@@ -147,7 +157,7 @@ export class Material implements IAnimatable {
     /**
      * Custom callback helping to override the default shader used in the material.
      */
-    public customShaderNameResolve: (shaderName: string, uniforms: string[], uniformBuffers: string[], samplers: string[], defines: MaterialDefines | string[], attributes?: string[]) => string;
+    public customShaderNameResolve: (shaderName: string, uniforms: string[], uniformBuffers: string[], samplers: string[], defines: MaterialDefines | string[], attributes?: string[], options?: ICustomShaderNameResolveOptions) => string;
 
     /**
      * Custom shadow depth material to use for shadow rendering instead of the in-built one

src/Materials/standardMaterial.ts

@@ -15,7 +15,7 @@ import { Mesh } from "../Meshes/mesh";
 import { ImageProcessingConfiguration, IImageProcessingConfigurationDefines } from "./imageProcessingConfiguration";
 import { ColorCurves } from "./colorCurves";
 import { FresnelParameters } from "./fresnelParameters";
-import { Material } from "../Materials/material";
+import { Material, ICustomShaderNameResolveOptions } from "../Materials/material";
 import { MaterialDefines } from "../Materials/materialDefines";
 import { PushMaterial } from "./pushMaterial";
 import { MaterialHelper } from "./materialHelper";
@@ -1164,8 +1164,10 @@ export class StandardMaterial extends PushMaterial {
                 maxSimultaneousLights: this._maxSimultaneousLights
             });
 
+            const csnrOptions: ICustomShaderNameResolveOptions = {};
+
             if (this.customShaderNameResolve) {
-                shaderName = this.customShaderNameResolve(shaderName, uniforms, uniformBuffers, samplers, defines, attribs);
+                shaderName = this.customShaderNameResolve(shaderName, uniforms, uniformBuffers, samplers, defines, attribs, csnrOptions);
             }
 
             var join = defines.toString();
@@ -1180,7 +1182,8 @@ export class StandardMaterial extends PushMaterial {
                 fallbacks: fallbacks,
                 onCompiled: this.onCompiled,
                 onError: this.onError,
-                indexParameters: { maxSimultaneousLights: this._maxSimultaneousLights, maxSimultaneousMorphTargets: defines.NUM_MORPH_INFLUENCERS }
+                indexParameters: { maxSimultaneousLights: this._maxSimultaneousLights, maxSimultaneousMorphTargets: defines.NUM_MORPH_INFLUENCERS },
+                processFinalCode: csnrOptions.processFinalCode,
             }, engine);
 
             if (effect) {