layout(triangles) in;
layout(triangle_strip, max_vertices = 3) out;

in int instance[];
in vec2 vPos[];

flat out float layer;

void main()
{
  gl_Layer = instance[0];
  layer = float(instance[0]);

  gl_Position = vec4(vPos[0], 0.0, 1.0);
  EmitVertex();

  gl_Position = vec4(vPos[1], 0.0, 1.0);
  EmitVertex();

  gl_Position = vec4(vPos[2], 0.0, 1.0);
  EmitVertex();

  EndPrimitive();
}