#version 430 core

layout  (local_size_x  =  1)  in;

struct Vertex {
    vec3 pos;
    vec3 norm;
    vec2 uv;
};

layout(std430, binding=0) readonly buffer Vertices {
    Vertex vertices[];
};

layout(std430, binding=1) readonly buffer EdgeIndices {
    unsigned int indices[][4];
};

layout(std430, binding=2) writeonly buffer Output {
    Vertex edges[];
};

void main(){
    edges[gl_GlobalInvocationID.x].uv = vec2(0.0, 0.0);

    Vertex a = vertices[indices[gl_GlobalInvocationID.x][0]];
    Vertex b = vertices[indices[gl_GlobalInvocationID.x][1]];
    Vertex c = vertices[indices[gl_GlobalInvocationID.x][2]];
    Vertex d = vertices[indices[gl_GlobalInvocationID.x][3]];

    vec3 pos;

    edges[gl_GlobalInvocationID.x].pos = 3.0f/8.0f * a.pos + 3.0f/8.0f * b.pos + 1.0f/8.0f * c.pos + 1.0f/8.0f * d.pos;
    edges[gl_GlobalInvocationID.x].norm = normalize(3.0f/8.0f * a.norm + 3.0f/8.0f * b.norm + 1.0f/8.0f * c.norm + 1.0f/8.0f * d.norm);
}