GltfLoader is slow populating buffers #2125
Description
GltfLoader is slow populating buffers. Like super slow. It takes ages to load the textures. They are read one byte at a time. From memory, so disk I/O is not the problem here. It takes way over 10 minutes (I had to stop it running). It is a long time. I profiled and the problems are the tangent generating and GltfUtils.populateXArray methods. In this particular case, the populateByteArray. But all of the populate methods could be significantly made faster.
int arrayIndex = 0;
byte[] buffer = new byte[numComponents];
while (index < end) {
stream.read(buffer, 0, numComponents);
System.arraycopy(buffer, 0, array, arrayIndex, numComponents);
arrayIndex += numComponents;
if (dataLength < stride) {
stream.skipBytes(stride - dataLength);
}
index += stride;
}
This is a great start, but with the images in this sample I used, come down to having dataLength == stride (both actually 1). So following shortcut should be considered:
private static void populateByteArray(byte[] array, LittleEndien stream, int count, int byteOffset, int byteStride, int numComponents, VertexBuffer.Format format) throws IOException {
int componentSize = format.getComponentSize();
int index = byteOffset;
int dataLength = componentSize * numComponents;
int stride = Math.max(dataLength, byteStride);
int end = count * stride + byteOffset;
stream.skipBytes(byteOffset);
// Shortcut, read all
if (dataLength == stride) {
byte[] buffer = new byte[end - index];
stream.read(buffer, 0, buffer.length);
System.arraycopy(buffer, 0, array, 0, buffer.length);
return;
}
int arrayIndex = 0;
byte[] buffer = new byte[numComponents];
while (index < end) {
stream.read(buffer, 0, numComponents);
System.arraycopy(buffer, 0, array, arrayIndex, numComponents);
arrayIndex += numComponents;
if (dataLength < stride) {
stream.skipBytes(stride - dataLength);
}
index += stride;
}
}
With this shortcut the data is just read instantly. The images are quite huge. I still haven't managed to read the scene to jME. So this is why I post this issue here, instead of a PR.
I tested with the Bistro scene. Loaded it in Blender, exported as GLB.
https://developer.nvidia.com/orca/amazon-lumberyard-bistro