Compute Shader test

voxel.comp

#version 460
layout(local_size_x = 4, local_size_y = 4, local_size_z = 4) in;

struct Sphere {
    vec4 center;
};

layout(binding = 1, std140) uniform Camera {
    vec4 pos;
    vec4 dir;
} camera;

layout(binding = 1, std430) buffer Shapes {
    Sphere shapes[16];
} shapes;

layout(binding = 0, std430) buffer ShapeCount {
    uint count;
} shape_count;

layout(binding = 0, r32f) uniform writeonly image3D voxel_image;

vec4 multiply_quat(vec4 quat, vec3 vec) {
    return vec4(
        quat.x * vec.x + quat.y * vec.y + quat.z * vec.z,
        quat.x * vec.y - quat.y * vec.x + quat.w * vec.z,
        quat.x * vec.z - quat.z * vec.x - quat.w * vec.y,
        quat.y * vec.z - quat.z * vec.y + quat.w * vec.x
    );
}

vec3 rotate_back(vec4 rotated, vec4 quat) {
    return vec3(
        rotated.x * quat.x - rotated.y * quat.y - rotated.z * quat.z - rotated.w * quat.w,
        rotated.x * quat.y + rotated.y * quat.x - rotated.z * quat.w + rotated.w * quat.z,
        rotated.x * quat.z + rotated.y * quat.w + rotated.z * quat.x - rotated.w * quat.y
    );
}

float len2(vec3 disvec) {
    return (disvec.x * disvec.x + disvec.y * disvec.y + disvec.z * disvec.z);
}

float field_distance(vec3 p) {
    Sphere shapes[16] = shapes.shapes;
    float minimum_distance = 4096.0;
    for (uint i = 0u; i < shape_count.count; ++i) {
        vec3 disvec = (p - shapes[i].center.xyz);
        float new_distance = sqrt(abs(len2(disvec))) - 1.0;
        minimum_distance = (new_distance < minimum_distance) ? new_distance : minimum_distance;
    }
    return minimum_distance;
}

void main() {
    uvec3 index = (gl_GlobalInvocationID * gl_WorkGroupSize) + gl_LocalInvocationID;
    vec3 p = vec3(index.x - 32u, index.y - 32u, -64.0);
    float len = sqrt(abs(len2(p)));
    vec4 conjugate_quat = vec4(1, -1, -1, -1);
    float d = 1.0 + (float(index.z) / float(16u));
    imageStore(voxel_image, ivec3(index), vec4(field_distance((camera.pos.xyz + rotate_back(multiply_quat(camera.dir, p / len), camera.dir * conjugate_quat) * d)), 0, 0, 0));
}