MoonWorksComputeSpriteBatch/shaders/spritebatch.comp

#version 450

struct Vertex
{
    vec3 position;
    vec2 texcoord;
    vec4 color;
};

// Binding 0: vertices
layout(set = 0, binding = 0) buffer Vertices
{
    Vertex vertices[ ];
};

// Binding 1: transform matrices
layout(set = 0, binding = 1) buffer Transforms
{
    mat4 transforms[ ];
};

layout(set = 2, binding = 0) uniform UBO
{
    uint vertexCount;
} ubo;

layout (local_size_x = 256) in;

void main()
{
    // Current buffer index
    uint index = gl_GlobalInvocationID.x;

    // Don't write past particle count
    if (index >= ubo.vertexCount)
    {
        return;
    }

    uint transformIndex = index / 4;
    mat4 transform = transforms[transformIndex];
    vec4 position = vec4(vertices[index].position, 1.0);

    vertices[index].position = vec3(transform * position);
}