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Renderers: Set premultipliedAlpha to true when using MultiplyBlending or SubtractiveBlending. #32542

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Renderers: Set premultipliedAlpha to true when using MultiplyBlending or SubtractiveBlending. #32542

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0193215
Renderers: Remove premultipliedAlpha requirement for MultiplyBlending…
mrdoob Dec 13, 2025
10f45d6
Removed premultipliedAlpha from relevant examples.
mrdoob Dec 13, 2025
e2f55ca
Fixed webgl_materials_blending.
mrdoob Dec 13, 2025
74e50e8
Renderers: Add warnOnce calls to incorrect blending modes.
mrdoob Dec 14, 2025
f02e6c1
Renderers: Set premultipliedAlpha to true when using MultiplyBlending…
mrdoob Dec 17, 2025
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2 changes: 1 addition & 1 deletion examples/misc_exporter_usdz.html
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Original file line number Diff line number Diff line change
Expand Up @@ -145,7 +145,7 @@

const geometry = new THREE.PlaneGeometry();
const material = new THREE.MeshBasicMaterial( {
map: shadowTexture, blending: THREE.MultiplyBlending, toneMapped: false, premultipliedAlpha: true
map: shadowTexture, blending: THREE.MultiplyBlending, toneMapped: false
} );

const mesh = new THREE.Mesh( geometry, material );
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1 change: 0 additions & 1 deletion examples/webgl_materials_blending.html
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Original file line number Diff line number Diff line change
Expand Up @@ -101,7 +101,6 @@
const material = new THREE.MeshBasicMaterial( { map: map } );
material.transparent = true;
material.blending = blending.constant;

material.premultipliedAlpha = true;

const x = ( i - blendings.length / 2 ) * 110;
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2 changes: 1 addition & 1 deletion examples/webgl_materials_car.html
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Original file line number Diff line number Diff line change
Expand Up @@ -171,7 +171,7 @@
const mesh = new THREE.Mesh(
new THREE.PlaneGeometry( 0.655 * 4, 1.3 * 4 ),
new THREE.MeshBasicMaterial( {
map: shadow, blending: THREE.MultiplyBlending, toneMapped: false, transparent: true, premultipliedAlpha: true
map: shadow, blending: THREE.MultiplyBlending, toneMapped: false, transparent: true
} )
);
mesh.rotation.x = - Math.PI / 2;
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2 changes: 1 addition & 1 deletion examples/webgl_materials_envmaps_groundprojected.html
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Expand Up @@ -112,7 +112,7 @@
const mesh = new THREE.Mesh(
new THREE.PlaneGeometry( 0.655 * 4, 1.3 * 4 ),
new THREE.MeshBasicMaterial( {
map: shadow, blending: THREE.MultiplyBlending, toneMapped: false, transparent: true, premultipliedAlpha: true
map: shadow, blending: THREE.MultiplyBlending, toneMapped: false, transparent: true
} )
);
mesh.rotation.x = - Math.PI / 2;
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21 changes: 12 additions & 9 deletions src/renderers/webgl-fallback/utils/WebGLState.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ import {
NeverDepth, AlwaysDepth, LessDepth, LessEqualDepth, EqualDepth, GreaterEqualDepth, GreaterDepth, NotEqualDepth
} from '../../../constants.js';
import { Vector4 } from '../../../math/Vector4.js';
import { error } from '../../../utils.js';
import { error, warnOnce } from '../../../utils.js';

let equationToGL, factorToGL;

Expand Down Expand Up @@ -376,14 +376,6 @@ class WebGLState {
gl.blendFuncSeparate( gl.SRC_ALPHA, gl.ONE, gl.ONE, gl.ONE );
break;

case SubtractiveBlending:
error( 'WebGLState: SubtractiveBlending requires material.premultipliedAlpha = true' );
break;

case MultiplyBlending:
error( 'WebGLState: MultiplyBlending requires material.premultipliedAlpha = true' );
break;

default:
error( 'WebGLState: Invalid blending: ', blending );
break;
Expand Down Expand Up @@ -749,6 +741,17 @@ class WebGLState {

this.setFlipSided( flipSided );

if ( material.premultipliedAlpha === false ) {

if ( material.blending === MultiplyBlending || material.blending === SubtractiveBlending ) {

warnOnce( 'WebGLState: Material premultipliedAlpha was set to true because MultiplyBlending and SubtractiveBlending require it.' );
material.premultipliedAlpha = true;

}

}

( material.blending === NormalBlending && material.transparent === false )
? this.setBlending( NoBlending )
: this.setBlending( material.blending, material.blendEquation, material.blendSrc, material.blendDst, material.blendEquationAlpha, material.blendSrcAlpha, material.blendDstAlpha, material.premultipliedAlpha );
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21 changes: 12 additions & 9 deletions src/renderers/webgl/WebGLState.js
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
import { NotEqualDepth, GreaterDepth, GreaterEqualDepth, EqualDepth, LessEqualDepth, LessDepth, AlwaysDepth, NeverDepth, CullFaceFront, CullFaceBack, CullFaceNone, DoubleSide, BackSide, CustomBlending, MultiplyBlending, SubtractiveBlending, AdditiveBlending, NoBlending, NormalBlending, AddEquation, SubtractEquation, ReverseSubtractEquation, MinEquation, MaxEquation, ZeroFactor, OneFactor, SrcColorFactor, SrcAlphaFactor, SrcAlphaSaturateFactor, DstColorFactor, DstAlphaFactor, OneMinusSrcColorFactor, OneMinusSrcAlphaFactor, OneMinusDstColorFactor, OneMinusDstAlphaFactor, ConstantColorFactor, OneMinusConstantColorFactor, ConstantAlphaFactor, OneMinusConstantAlphaFactor } from '../../constants.js';
import { Color } from '../../math/Color.js';
import { Vector4 } from '../../math/Vector4.js';
import { error } from '../../utils.js';
import { error, warnOnce } from '../../utils.js';

const reversedFuncs = {
[ NeverDepth ]: AlwaysDepth,
Expand Down Expand Up @@ -689,14 +689,6 @@ function WebGLState( gl, extensions ) {
gl.blendFuncSeparate( gl.SRC_ALPHA, gl.ONE, gl.ONE, gl.ONE );
break;

case SubtractiveBlending:
error( 'WebGLState: SubtractiveBlending requires material.premultipliedAlpha = true' );
break;

case MultiplyBlending:
error( 'WebGLState: MultiplyBlending requires material.premultipliedAlpha = true' );
break;

default:
error( 'WebGLState: Invalid blending: ', blending );
break;
Expand Down Expand Up @@ -772,6 +764,17 @@ function WebGLState( gl, extensions ) {

setFlipSided( flipSided );

if ( material.premultipliedAlpha === false ) {

if ( material.blending === MultiplyBlending || material.blending === SubtractiveBlending ) {

warnOnce( 'WebGLState: Material premultipliedAlpha was set to true because MultiplyBlending and SubtractiveBlending require it.' );
material.premultipliedAlpha = true;

}

}

( material.blending === NormalBlending && material.transparent === false )
? setBlending( NoBlending )
: setBlending( material.blending, material.blendEquation, material.blendSrc, material.blendDst, material.blendEquationAlpha, material.blendSrcAlpha, material.blendDstAlpha, material.blendColor, material.blendAlpha, material.premultipliedAlpha );
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21 changes: 12 additions & 9 deletions src/renderers/webgpu/utils/WebGPUPipelineUtils.js
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ import {
NeverStencilFunc, AlwaysStencilFunc, LessStencilFunc, LessEqualStencilFunc, EqualStencilFunc, GreaterEqualStencilFunc, GreaterStencilFunc, NotEqualStencilFunc
} from '../../../constants.js';

import { error } from '../../../utils.js';
import { error, warnOnce } from '../../../utils.js';

/**
* A WebGPU backend utility module for managing pipelines.
Expand Down Expand Up @@ -120,6 +120,17 @@ class WebGPUPipelineUtils {

let blending;

if ( material.premultipliedAlpha === false ) {

if ( material.blending === MultiplyBlending || material.blending === SubtractiveBlending ) {

warnOnce( 'WebGPURenderer: Material premultipliedAlpha was set to true because MultiplyBlending and SubtractiveBlending require it.' );
material.premultipliedAlpha = true;

}

}

if ( material.blending !== NoBlending && ( material.blending !== NormalBlending || material.transparent !== false ) ) {

blending = this._getBlending( material );
Expand Down Expand Up @@ -447,14 +458,6 @@ class WebGPUPipelineUtils {
setBlend( GPUBlendFactor.SrcAlpha, GPUBlendFactor.One, GPUBlendFactor.One, GPUBlendFactor.One );
break;

case SubtractiveBlending:
error( 'WebGPURenderer: SubtractiveBlending requires material.premultipliedAlpha = true' );
break;

case MultiplyBlending:
error( 'WebGPURenderer: MultiplyBlending requires material.premultipliedAlpha = true' );
break;

}

}
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