#version 430

layout(quads, equal_spacing, ccw) in;  // Define the type of patch (e.g., quads)

layout(location = 0) uniform mat4 M;

layout(std140, binding = 0) uniform SceneUniforms
{
    mat4 PV;	//camera projection * view matrix
    vec4 eye_w;	//world-space eye position
};

in VertexData {
    vec2 tex_coord;
} inData[];

out vec3 frag_position;  // Ensure this matches the input in fragment.glsl

out VertexData {
    vec2 tex_coord;
} outData;

void main()
{
    // Interpolate the position using the barycentric coordinates from tessellation
    vec3 pos = mix(mix(gl_in[0].gl_Position.xyz, gl_in[1].gl_Position.xyz, gl_TessCoord.x),
                   mix(gl_in[3].gl_Position.xyz, gl_in[2].gl_Position.xyz, gl_TessCoord.x),
                   gl_TessCoord.y);
    
    frag_position = pos;

    outData.tex_coord = mix(mix(inData[0].tex_coord, inData[1].tex_coord, gl_TessCoord.x),
                            mix(inData[3].tex_coord, inData[2].tex_coord, gl_TessCoord.x),
                            gl_TessCoord.y);

    gl_Position = PV*M*vec4(pos, 1.0);
}