@vs vs
in vec3 a_pos;

void main()
{
  vec3 pos = a_pos;
  pos -= 0.5;
  pos *= 2;
  gl_Position = vec4(pos.xy, 0, 1.0);
}
@end

@fs fs
out vec4 color;

void main()
{
  color = vec4(1.0);
}
@end

@program p vs fs