terravisor/shaders/tessellation_eval.glsl

#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
};

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

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;

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