BabylonJS · sebavan · Sep 2, 2025 · Sep 2, 2025 · Sep 2, 2025
diff --git a/packages/dev/core/src/Engines/Native/nativeShaderProcessors.ts b/packages/dev/core/src/Engines/Native/nativeShaderProcessors.ts
@@ -79,6 +79,9 @@ export class NativeShaderProcessor implements IShaderProcessor {
             code = code.replace(/gl_FragData/g, "glFragData");
             code = code.replace(/void\s+?main\s*\(/g, (hasDrawBuffersExtension || hasOutput ? "" : "layout(location = 0) out vec4 glFragColor;\n") + "void main(");
         } else {
+            if (defines.indexOf("#define VERTEXOUTPUT_INVARIANT") >= 0) {
+                code = "invariant gl_Position;\n" + code;
+            }
             if (this._nativeProcessingContext?.injectInVertexMain) {
                 code = InjectStartingAndEndingCode(code, "void main", this._nativeProcessingContext.injectInVertexMain);
             }

diff --git a/packages/dev/core/src/Engines/WebGL/webGL2ShaderProcessors.ts b/packages/dev/core/src/Engines/WebGL/webGL2ShaderProcessors.ts
@@ -46,6 +46,9 @@ export class WebGL2ShaderProcessor implements IShaderProcessor {
             code = code.replace(/gl_FragData/g, "glFragData");
             code = code.replace(/void\s+?main\s*\(/g, (hasDrawBuffersExtension || hasOutput ? "" : outputDeclaration) + "void main(");
         } else {
+            if (defines.indexOf("#define VERTEXOUTPUT_INVARIANT") >= 0) {
+                code = "invariant gl_Position;\n" + code;
+            }
             const hasMultiviewExtension = defines.indexOf("#define MULTIVIEW") !== -1;
             if (hasMultiviewExtension) {
                 return "#extension GL_OVR_multiview2 : require\nlayout (num_views = 2) in;\n" + code;

diff --git a/packages/dev/core/src/Engines/WebGPU/webgpuShaderProcessorsGLSL.ts b/packages/dev/core/src/Engines/WebGPU/webgpuShaderProcessorsGLSL.ts
@@ -281,7 +281,8 @@ export class WebGPUShaderProcessorGLSL extends WebGPUShaderProcessor {
         defines: string[],
         isFragment: boolean,
         _processingContext: Nullable<_IShaderProcessingContext>,
-        _parameters?: { [key: string]: number | string | boolean | undefined }
+        _parameters: { [key: string]: number | string | boolean | undefined },
+        preProcessors: { [key: string]: string }
     ): string {
         const hasDrawBuffersExtension = code.search(/#extension.+GL_EXT_draw_buffers.+require/) !== -1;
 
@@ -325,6 +326,9 @@ export class WebGPUShaderProcessorGLSL extends WebGPUShaderProcessor {
                 code = InjectStartingAndEndingCode(code, "void main", fragCoordCode);
             }
         } else {
+            if ("VERTEXOUTPUT_INVARIANT" in preProcessors) {
+                code = "invariant gl_Position;\n" + code;
+            }
             code = code.replace(/gl_InstanceID/g, "gl_InstanceIndex");
             code = code.replace(/gl_VertexID/g, "gl_VertexIndex");
             const hasMultiviewExtension = defines.indexOf("#define MULTIVIEW") !== -1;

diff --git a/packages/dev/core/src/Engines/WebGPU/webgpuShaderProcessorsWGSL.ts b/packages/dev/core/src/Engines/WebGPU/webgpuShaderProcessorsWGSL.ts
@@ -331,6 +331,10 @@ export class WebGPUShaderProcessorWGSL extends WebGPUShaderProcessor {
 
         code = this._convertDefinesToConst(preProcessors) + code;
 
+        if ("VERTEXOUTPUT_INVARIANT" in preProcessors) {
+            code = "#define VERTEXOUTPUT_INVARIANT\n" + code;
+        }
+
         return code;
     }
 
@@ -375,7 +379,8 @@ export class WebGPUShaderProcessorWGSL extends WebGPUShaderProcessor {
             vertexInputs += "\n};\nvar<private> vertexInputs : VertexInputs_;\n";
         }
 
-        let vertexOutputs = "struct FragmentInputs {\n  @builtin(position) position : vec4<f32>,\n";
+        let vertexOutputs =
+            "struct FragmentInputs {\n  @builtin(position)" + (vertexCode.indexOf("#define VERTEXOUTPUT_INVARIANT") >= 0 ? " @invariant" : "") + " position : vec4<f32>,\n";
         if (this._varyingsWGSL.length > 0) {
             vertexOutputs += this._varyingsWGSL.join("\n");
         }

diff --git a/packages/dev/core/src/Materials/Background/backgroundMaterial.ts b/packages/dev/core/src/Materials/Background/backgroundMaterial.ts
@@ -889,7 +889,19 @@ export class BackgroundMaterial extends PushMaterial {
         }
 
         // Misc.
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, this.needAlphaTestingForMesh(mesh), defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            this.needAlphaTestingForMesh(mesh),
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         // Values that need to be evaluated on every frame
         PrepareDefinesForFrameBoundValues(scene, engine, this, defines, useInstances, null, subMesh.getRenderingMesh().hasThinInstances);

diff --git a/packages/dev/core/src/Materials/GaussianSplatting/gaussianSplattingMaterial.ts b/packages/dev/core/src/Materials/GaussianSplatting/gaussianSplattingMaterial.ts
@@ -162,7 +162,19 @@ export class GaussianSplattingMaterial extends PushMaterial {
         const gsMesh = mesh as GaussianSplattingMesh;
 
         // Misc.
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, false, defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            false,
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         // Values that need to be evaluated on every frame
         PrepareDefinesForFrameBoundValues(scene, engine, this, defines, useInstances, null, true);

diff --git a/packages/dev/core/src/Materials/PBR/pbrBaseMaterial.ts b/packages/dev/core/src/Materials/PBR/pbrBaseMaterial.ts
@@ -2010,7 +2010,8 @@ export abstract class PBRBaseMaterial extends PushMaterial {
                 defines,
                 this._applyDecalMapAfterDetailMap,
                 this._useVertexPulling,
-                renderingMesh
+                renderingMesh,
+                this._setVertexOutputInvariant
             );
             defines.UNLIT = this._unlit || ((this.pointsCloud || this.wireframe) && !mesh.isVerticesDataPresent(VertexBuffer.NormalKind));
             defines.DEBUGMODE = this._debugMode;

diff --git a/packages/dev/core/src/Materials/material.ts b/packages/dev/core/src/Materials/material.ts
@@ -869,6 +869,28 @@ export class Material implements IAnimatable, IClipPlanesHolder {
         this._markAllSubMeshesAsMiscDirty();
     }
 
+    @serialize()
+    protected _setVertexOutputInvariant = false;
+    /**
+     * Gets or sets the vertex output invariant state
+     * Setting this property to true will force the shader compiler to disable some optimization to make sure the vertex output is always calculated
+     * the same way across different compilation units.
+     * You may need to enable this option if you are seeing some depth artifacts when using a depth pre-pass, for e.g.
+     * Note that this may have an impact on performance, so leave this option disabled if not needed.
+     */
+    public get setVertexOutputInvariant(): boolean {
+        return this._setVertexOutputInvariant;
+    }
+
+    public set setVertexOutputInvariant(value: boolean) {
+        if (this._setVertexOutputInvariant === value) {
+            return;
+        }
+
+        this._setVertexOutputInvariant = value;
+        this._markAllSubMeshesAsMiscDirty();
+    }
+
     /**
      * @internal
      * Stores the effects for the material

diff --git a/packages/dev/core/src/Materials/materialDefines.ts b/packages/dev/core/src/Materials/materialDefines.ts
@@ -2,6 +2,8 @@
  * Manages the defines for the Material
  */
 export class MaterialDefines {
+    public VERTEXOUTPUT_INVARIANT = false;
+
     /** @internal */
     protected _keys: string[] = [];
     private _isDirty = true;

diff --git a/packages/dev/core/src/Materials/materialHelper.functions.ts b/packages/dev/core/src/Materials/materialHelper.functions.ts
@@ -501,6 +501,7 @@ export function GetFogState(mesh: AbstractMesh, scene: Scene) {
  * @param applyDecalAfterDetail Defines if the decal is applied after or before the detail
  * @param useVertexPulling Defines if vertex pulling is used
  * @param renderingMesh The mesh used for rendering
+ * @param setVertexOutputInvariant Defines if the vertex output should be invariant
  */
 export function PrepareDefinesForMisc(
     mesh: AbstractMesh,
@@ -512,7 +513,8 @@ export function PrepareDefinesForMisc(
     defines: any,
     applyDecalAfterDetail: boolean = false,
     useVertexPulling: boolean = false,
-    renderingMesh?: AbstractMesh
+    renderingMesh?: AbstractMesh,
+    setVertexOutputInvariant?: boolean
 ): void {
     if (defines._areMiscDirty) {
         defines["LOGARITHMICDEPTH"] = useLogarithmicDepth;
@@ -527,6 +529,8 @@ export function PrepareDefinesForMisc(
 
         defines["VERTEX_PULLING_USE_INDEX_BUFFER"] = !!indexBuffer;
         defines["VERTEX_PULLING_INDEX_BUFFER_32BITS"] = indexBuffer ? indexBuffer.is32Bits : false;
+
+        defines["VERTEXOUTPUT_INVARIANT"] = !!setVertexOutputInvariant;
     }
 }
 

diff --git a/packages/dev/core/src/Materials/standardMaterial.ts b/packages/dev/core/src/Materials/standardMaterial.ts
@@ -1250,7 +1250,8 @@ export class StandardMaterial extends PushMaterial {
             defines,
             this._applyDecalMapAfterDetailMap,
             this._useVertexPulling,
-            subMesh.getRenderingMesh()
+            subMesh.getRenderingMesh(),
+            this._setVertexOutputInvariant
         );
 
         // Values that need to be evaluated on every frame

diff --git a/packages/dev/core/src/Shaders/pbr.vertex.fx b/packages/dev/core/src/Shaders/pbr.vertex.fx
@@ -187,14 +187,6 @@ void main(void) {
             // Bend the normal towards the viewer based on the diffuse roughness
             vec3 viewDirectionW = normalize(vEyePosition.xyz - vPositionW);
 
-            #if !defined(NATIVE) && !defined(WEBGPU)
-                // Next two lines fixes a flickering that occurs on some specific circumstances on MacOS/iOS
-                // See https://forum.babylonjs.com/t/needdepthprepass-creates-flickering-in-8-6-2/58421/12
-                // Note that the variable passed to isnan doesn't matter...
-                bool bbb = any(isnan(position));
-                if (bbb) { }
-            #endif
-
             float NdotV = max(dot(vNormalW, viewDirectionW), 0.0);
             vec3 roughNormal = mix(vNormalW, viewDirectionW, (0.5 * (1.0 - NdotV)) * baseDiffuseRoughness);
             vec3 reflectionVector = vec3(reflectionMatrix * vec4(roughNormal, 0)).xyz;

diff --git a/packages/dev/materials/src/cell/cellMaterial.ts b/packages/dev/materials/src/cell/cellMaterial.ts
@@ -154,7 +154,19 @@ export class CellMaterial extends PushMaterial {
         defines.CELLBASIC = !this.computeHighLevel;
 
         // Misc.
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, this.needAlphaTestingForMesh(mesh), defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            this.needAlphaTestingForMesh(mesh),
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         // Lights
         defines._needNormals = PrepareDefinesForLights(scene, mesh, defines, false, this._maxSimultaneousLights, this._disableLighting);

diff --git a/packages/dev/materials/src/fur/furMaterial.ts b/packages/dev/materials/src/fur/furMaterial.ts
@@ -230,7 +230,19 @@ export class FurMaterial extends PushMaterial {
         }
 
         // Misc.
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, this.needAlphaTestingForMesh(mesh), defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            this.needAlphaTestingForMesh(mesh),
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         // Lights
         defines._needNormals = PrepareDefinesForLights(scene, mesh, defines, false, this._maxSimultaneousLights, this._disableLighting);

diff --git a/packages/dev/materials/src/gradient/gradientMaterial.ts b/packages/dev/materials/src/gradient/gradientMaterial.ts
@@ -144,7 +144,19 @@ export class GradientMaterial extends PushMaterial {
 
         PrepareDefinesForFrameBoundValues(scene, engine, this, defines, useInstances ? true : false);
 
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, this.needAlphaTestingForMesh(mesh), defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            this.needAlphaTestingForMesh(mesh),
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         defines._needNormals = PrepareDefinesForLights(scene, mesh, defines, false, this._maxSimultaneousLights, this._disableLighting);
 

diff --git a/packages/dev/materials/src/grid/gridMaterial.ts b/packages/dev/materials/src/grid/gridMaterial.ts
@@ -204,7 +204,7 @@ export class GridMaterial extends PushMaterial {
             }
         }
 
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, false, this.fogEnabled, false, defines);
+        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, false, this.fogEnabled, false, defines, undefined, undefined, undefined, this._setVertexOutputInvariant);
 
         // Values that need to be evaluated on every frame
         PrepareDefinesForFrameBoundValues(scene, scene.getEngine(), this, defines, !!useInstances);

diff --git a/packages/dev/materials/src/lava/lavaMaterial.ts b/packages/dev/materials/src/lava/lavaMaterial.ts
@@ -212,7 +212,19 @@ export class LavaMaterial extends PushMaterial {
         }
 
         // Misc.
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, this.needAlphaTestingForMesh(mesh), defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            this.needAlphaTestingForMesh(mesh),
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         // Lights
         defines._needNormals = true;

diff --git a/packages/dev/materials/src/mix/mixMaterial.ts b/packages/dev/materials/src/mix/mixMaterial.ts
@@ -240,7 +240,19 @@ export class MixMaterial extends PushMaterial {
         }
 
         // Misc.
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, this.needAlphaTestingForMesh(mesh), defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            this.needAlphaTestingForMesh(mesh),
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         // Lights
         defines._needNormals = PrepareDefinesForLights(scene, mesh, defines, false, this._maxSimultaneousLights, this._disableLighting);

diff --git a/packages/dev/materials/src/normal/normalMaterial.ts b/packages/dev/materials/src/normal/normalMaterial.ts
@@ -187,7 +187,19 @@ export class NormalMaterial extends PushMaterial {
         }
 
         // Misc.
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, this.needAlphaTestingForMesh(mesh), defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            this.needAlphaTestingForMesh(mesh),
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         // Lights
         defines._needNormals = true;

diff --git a/packages/dev/materials/src/shadowOnly/shadowOnlyMaterial.ts b/packages/dev/materials/src/shadowOnly/shadowOnlyMaterial.ts
@@ -141,7 +141,19 @@ export class ShadowOnlyMaterial extends PushMaterial {
 
         PrepareDefinesForFrameBoundValues(scene, engine, this, defines, useInstances ? true : false);
 
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, this.needAlphaTestingForMesh(mesh), defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            this.needAlphaTestingForMesh(mesh),
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         defines._needNormals = PrepareDefinesForLights(scene, mesh, defines, false, 1);
 

diff --git a/packages/dev/materials/src/simple/simpleMaterial.ts b/packages/dev/materials/src/simple/simpleMaterial.ts
@@ -143,7 +143,19 @@ export class SimpleMaterial extends PushMaterial {
         }
 
         // Misc.
-        PrepareDefinesForMisc(mesh, scene, this._useLogarithmicDepth, this.pointsCloud, this.fogEnabled, this.needAlphaTestingForMesh(mesh), defines);
+        PrepareDefinesForMisc(
+            mesh,
+            scene,
+            this._useLogarithmicDepth,
+            this.pointsCloud,
+            this.fogEnabled,
+            this.needAlphaTestingForMesh(mesh),
+            defines,
+            undefined,
+            undefined,
+            undefined,
+            this._setVertexOutputInvariant
+        );
 
         // Lights
         defines._needNormals = PrepareDefinesForLights(scene, mesh, defines, false, this._maxSimultaneousLights, this._disableLighting);