Gouraud Shading our Triangle (cont’d)

out vec3 vColor;
    
void main() {
    vColor[gl_VertexID] = 1.0;

    float vid = float(gl_VertexID);

    const float Pi = 3.14159265358979;
    const float DegreesToRadians = Pi / 180.0;

    float angle = vid * 120.0 /* Degrees */ * DegreesToRadians;

    vec2 v = vec2(cos(angle), sin(angle));
    v.x -= 0.25;

    gl_Position = vec4(v, 0.0, 1.0);
}

in  vec3 vColor; 
out vec4 fColor;

void main() {
    fColor = vec4(vColor, 1.0);
}