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

#version 330

layout (triangles) in;
layout (triangle_strip, max_vertices = 7) out;

uniform float anti_alias_width;
uniform float pixel_size;
uniform vec3 corner;

in vec3 verts[3];
in vec4 v_color[3];
in vec3 v_base_point[3];
in float v_vert_index[3];


out vec4 color;

out float orientation;
// uv space is where the curve coincides with y = x^2
out vec2 uv_coords;


// Analog of import for manim only
#INSERT get_gl_Position.glsl
#INSERT get_unit_normal.glsl
#INSERT finalize_color.glsl


void emit_vertex_wrapper(vec3 point, vec4 v_color, vec3 unit_normal){
    color = finalize_color(v_color, point, unit_normal);
    gl_Position = get_gl_Position(point);
    EmitVertex();
}


void main(){
    // We use the triangle strip primative, but
    // actually only need every other strip element
    if (int(v_vert_index[0]) % 2 == 1) return;

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

    vec3 unit_normal = get_unit_normal(verts[0], verts[1], verts[2]);

    // Emit main triangle
    orientation = 0.0;
    uv_coords = vec2(0.0);
    emit_vertex_wrapper(verts[2], v_color[2], unit_normal);
    emit_vertex_wrapper(v_base_point[0], v_color[1], unit_normal);
    emit_vertex_wrapper(verts[0], v_color[0], unit_normal);

    // Emit edge triangle
    orientation = 1.0;
    uv_coords = vec2(0, 0);
    // Two dummies
    emit_vertex_wrapper(verts[0], v_color[0], unit_normal);
    emit_vertex_wrapper(verts[0], v_color[0], unit_normal);
    // Inner corner
    uv_coords = vec2(0.5, 0);
    emit_vertex_wrapper(verts[1], v_color[1], unit_normal);
    // Last corner
    uv_coords = vec2(1.0, 1.0);
    emit_vertex_wrapper(verts[2], v_color[2], unit_normal);
    EndPrimitive();
}