prepareUniformsGroup method

WebGLUniformsGroups prepareUniformsGroup(UniformsGroup uniformsGroup)

Implementation

WebGLUniformsGroups prepareUniformsGroup(UniformsGroup uniformsGroup ) {
	// determine total buffer size according to the STD140 layout
	// Hint: STD140 is the only supported layout in WebGL 2
	final uniforms = uniformsGroup.uniforms;

	int offset = 0; // global buffer offset in bytes
	const int chunkSize = 16; // size of a chunk in bytes

	for (int i = 0, l = uniforms.length; i < l; i ++ ) {
		final List<Uniform> uniformArray = [uniforms[ i ]];

		for (int j = 0, jl = uniformArray.length; j < jl; j ++ ) {
			final uniform = uniformArray[ j ];
			final values = uniform.value is List ? uniform.value : [ uniform.value ];

			for (int k = 0, kl = values.length; k < kl; k ++ ) {
				final value = values[ k ];
				final info = getUniformSize( value );
				// Calculate the chunk offset
				final chunkOffset = offset % chunkSize;
				final chunkPadding = chunkOffset % info['boundary']!; // required padding to match boundary
				final chunkStart = chunkOffset + chunkPadding; // the start position in the current chunk for the data

          offset += chunkPadding;

				// Check for chunk overflow
				if ( chunkStart != 0 && ( chunkSize - chunkStart ) < info['storage']! ) {
					// Add padding and adjust offset
					offset += ( chunkSize - chunkStart );
				}

				// the following two properties will be used for partial buffer updates
				uniform.data = Float32Array( info['storage']! ~/ Float32List.bytesPerElement);
				uniform.offset = offset;

				// Update the global offset
				offset += info['storage']!;
			}
		}
	}

	// ensure correct final padding

	final chunkOffset = offset % chunkSize;

	if ( chunkOffset > 0 ) offset += ( chunkSize - chunkOffset );

	uniformsGroup.size = offset;
	uniformsGroup.cache = {};

	return this;
}