#define worldCurvature 0 // [0 1 2]
#define worldRadius 512 // [1024 512 256 -256]

void world_curvature() {
	#if worldCurvature == 1
		float z = gl_Position.z * gl_Position.z;
		gl_Position.y -= 2 * z / worldRadius;
	#elif worldCurvature == 2
		vec2 xz = gl_Position.xz;
		gl_Position.y -= ceil(( dot(xz, xz) * 5 ) / worldRadius) / 5;
	#endif
}