The KHR_parallel_shader_compile
extension is part of the WebGL API and enables a non-blocking poll operation, so that compile/link status availability (COMPLETION_STATUS_KHR
) can be queried without potentially incurring stalls. In other words you can check the status of your shaders compiling without blocking the runtime.
WebGL extensions are available using the WebGLRenderingContext.getExtension()
method. For more information, see also Using Extensions in the WebGL tutorial.
Enable the extension:
const ext = gl.getExtension("KHR_parallel_shader_compile");
In general, best practice with or without the extension is:
for (const x of shaders) gl.compileShader(x);
for (const x of programs) gl.linkProgram(x);
With the extension, apps would be able to poll whether programs have linked without janking, but these are likely to take the same total wall time to link:
function* linkingProgress(programs) {
const ext = gl.getExtension("KHR_parallel_shader_compile");
let todo = programs.slice();
while (todo.length) {
if (ext) {
todo = todo.filter(
(x) => !gl.getProgramParameter(x, ext.COMPLETION_STATUS_KHR),
);
} else {
const x = todo.pop();
gl.getProgramParameter(x, gl.LINK_STATUS);
}
if (!todo.length) return;
yield 1.0 - todo.length / programs.length;
}
}