3b1b-manim/manimlib/shaders/quadratic_bezier_depth/geom.glsl

#version 330

layout (triangles) in;
layout (triangle_strip, max_vertices = 6) out;

in vec3 verts[3];
in vec3 v_base_point[3];
in int v_vert_index[3];

out float depth;

#INSERT emit_gl_Position.glsl


void emit_triangle(vec3 points[3]){
    for(int i = 0; i < 3; i++){
        emit_gl_Position(points[i]);
        // float z = gl_Position.z / gl_Position.w;
        // depth = 0.5 * z + 0.5;
        EmitVertex();
    }
    EndPrimitive();
}


void main(){
    // Vector graphic shaders use TRIANGLE_STRIP, but only
    // every other one needs to be rendered
    if (v_vert_index[0] % 2 != 0) return;

    // Curves are marked as ended when the handle after
    // the first anchor is set equal to that anchor
    if (verts[0] == verts[1]) return;

    // Emit main triangle
    emit_triangle(vec3[3](v_base_point[0], verts[0], verts[2]));
    emit_triangle(vec3[3](verts[0], verts[1], verts[2]));
}