#include <metal_stdlib>
using namespace metal;

struct VertexOut {
    float4 position [[position]];
    float4 color;
};

vertex VertexOut triangle_vertex_main(uint vertexID [[vertex_id]]) {
    VertexOut out;

    // Triángulo simple en coordenadas normalized device coordinates
    float2 positions[3] = {
        float2( 0.0,  0.5),  // Top
        float2(-0.5, -0.5),  // Bottom left
        float2( 0.5, -0.5)   // Bottom right
    };

    float4 colors[3] = {
        float4(1, 0, 0, 1),  // Red
        float4(0, 1, 0, 1),  // Green
        float4(0, 0, 1, 1)   // Blue
    };

    out.position = float4(positions[vertexID], 0.0, 1.0);
    out.color = colors[vertexID];

    return out;
}

fragment float4 triangle_fragment_main(VertexOut in [[stage_in]]) {
    return in.color;
}