float theta = 2.0 * PI * world_position.x / world_radius;
float phi = 2.0 * atan(exp(world_position.y / world_radius)) - PI / 2.0;
float radius = world_position.z

gl_Position = vec4(radius * vec3(sin(theta)*cos(phi), sin(phi), cos(theta)*cos(phi)), 1.0);