added missing padding to integer vertex attributes

examples/jsm/exporters/GLTFExporter.js

@@ -1054,10 +1054,16 @@ class GLTFWriter {
 		if ( target !== undefined ) bufferViewDef.target = target;
 
 		if ( target === WEBGL_CONSTANTS.ARRAY_BUFFER ) {
-
+			
 			// Only define byteStride for vertex attributes.
+
 			bufferViewDef.byteStride = attribute.itemSize * componentSize;
 
+			if(componentSize === 1){
+				const paddedArray = new Uint8Array(getPaddedArrayBuffer(attribute.array.buffer));
+				attribute.array = paddedArray;
+			}
+
 		}
 
 		this.byteOffset += byteLength;