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GLTFLoader: Fix alpha detection for colorType=3,4 #20376

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Merged
merged 1 commit into from
Sep 18, 2020
Merged

GLTFLoader: Fix alpha detection for colorType=3,4 #20376

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8 changes: 7 additions & 1 deletion examples/js/loaders/GLTFLoader.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2170,8 +2170,14 @@ THREE.GLTFLoader = ( function () {

if ( source.mimeType === 'image/png' ) {

// Inspect the PNG 'IHDR' chunk to determine whether the image could have an
// alpha channel. This check is conservative — the image could have an alpha
// channel with all values == 1, and the indexed type (colorType == 3) only
// sometimes contains alpha.
//
// https://en.wikipedia.org/wiki/Portable_Network_Graphics#File_header
hasAlpha = new DataView( bufferView, 25, 1 ).getUint8( 0, false ) === 6;
var colorType = new DataView( bufferView, 25, 1 ).getUint8( 0, false );
hasAlpha = colorType === 6 || colorType === 4 || colorType === 3;

}

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8 changes: 7 additions & 1 deletion examples/jsm/loaders/GLTFLoader.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2233,8 +2233,14 @@ var GLTFLoader = ( function () {

if ( source.mimeType === 'image/png' ) {

// Inspect the PNG 'IHDR' chunk to determine whether the image could have an
// alpha channel. This check is conservative — the image could have an alpha
// channel with all values == 1, and the indexed type (colorType == 3) only
// sometimes contains alpha.
//
// https://en.wikipedia.org/wiki/Portable_Network_Graphics#File_header
hasAlpha = new DataView( bufferView, 25, 1 ).getUint8( 0, false ) === 6;
var colorType = new DataView( bufferView, 25, 1 ).getUint8( 0, false );
hasAlpha = colorType === 6 || colorType === 4 || colorType === 3;

}

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