#version 450 core

// Explicitly set the output location for Vulkan
layout(location = 0) out vec4 vColor;

void main() {
    // Initialize with default values
    vec2 pos = vec2(0.0);
    vec4 color = vec4(0.0);

    // Use Vulkan's gl_VertexIndex instead of gl_VertexID
    switch(gl_VertexIndex) {
        case 0:
            pos = vec2(-1.0, -1.0);
            color = vec4(1.0, 0.0, 0.0, 1.0);
            break;
        case 1:
            pos = vec2(1.0, -1.0);
            color = vec4(0.0, 1.0, 0.0, 1.0);
            break;
        case 2:
            pos = vec2(0.0, 1.0);
            color = vec4(0.0, 0.0, 1.0, 1.0);
            break;
    }

    gl_Position = vec4(pos, 0.0, 1.0);
    vColor = color;
}