Ipotrick

What is "Work Expansion"

In a GPU-driven renderer, "work expansion" is a commonly occurring problem. "Work Expansion" means that a single item of work spawns N following work items. Typically one work item will be executed by one shader thread/invocation.

An example for work expansion is gpu driven meshlet culling following mesh culling. In this example a "work item" is culling a mesh, where each mesh cull work item spawns N following meshlet cull work items.

There are many diverse cases of this problem and many solutions. Some are trivial to solve, for example, when N (how many work items are spawned) is fixed.

alichraghi

What does it look like?

Here is a simple fragment shader with uniform buffers:

const std = @import("std");
const gpu = std.gpu;

const UBO = extern struct {
    object_color: @Vector(4, f32),
    light_color: @Vector(4, f32),