//we will be using glsl version 4.5 syntax #version 450 void main() { //const array of positions for the triangle const vec2 positions[3] = vec2[3]( vec2(0.5, 0.5), vec2(-0.5, 0.5), vec2(0.0, -0.5) ); //output the position of each vertex gl_Position = vec4(positions[gl_VertexIndex], 0.0, 1.0); }