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fix: Fix alignment of integer vertex attributes #408

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Merged
CodyJasonBennett merged 1 commit into from
Feb 20, 2025
Merged

fix: Fix alignment of integer vertex attributes #408

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13 changes: 11 additions & 2 deletions src/exporters/GLTFExporter.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1024,7 +1024,13 @@ class GLTFWriter {
componentSize = 4
}

const byteLength = getPaddedBufferSize(count * attribute.itemSize * componentSize)
let byteStride = attribute.itemSize * componentSize
if (target === WEBGL_CONSTANTS.ARRAY_BUFFER) {
// Each element of a vertex attribute MUST be aligned to 4-byte boundaries
// inside a bufferView
byteStride = Math.ceil(byteStride / 4) * 4
}
const byteLength = getPaddedBufferSize(count * byteStride)
const dataView = new DataView(new ArrayBuffer(byteLength))
let offset = 0

Expand Down Expand Up @@ -1065,6 +1071,9 @@ class GLTFWriter {

offset += componentSize
}
if (offset % byteStride !== 0) {
offset += byteStride - (offset % byteStride)
}
}

const bufferViewDef = {
Expand All @@ -1077,7 +1086,7 @@ class GLTFWriter {

if (target === WEBGL_CONSTANTS.ARRAY_BUFFER) {
// Only define byteStride for vertex attributes.
bufferViewDef.byteStride = attribute.itemSize * componentSize
bufferViewDef.byteStride = byteStride
}

this.byteOffset += byteLength
Expand Down