#include <metal_stdlib>

using namespace metal;

typedef struct {
	float4 position;
	float4 colour;
} vertex_struct;

struct ToFragStruct {
    float4 position [[position]];
    float4 colour;
};

struct Projection {
    float4x4 projection;
};

struct Transformation {
    float4x4 transformation;
};

// vertex shader function
vertex ToFragStruct vertex_shader(device vertex_struct* vertex_array [[ buffer(0) ]],
                                  constant Projection &projection [[buffer(1)]],
                                  constant Transformation &transformation [[buffer(2)]],
                                  unsigned int vid [[ vertex_id ]])
{
    ToFragStruct out;

    out.position = projection.projection * transformation.transformation * vertex_array[vid].position;
    out.colour = vertex_array[vid].colour;

    return out;
}

// fragment shader function
fragment float4 fragment_shader(ToFragStruct in [[stage_in]])
{
    return in.colour;
}