uniform mat4 uWorld;
uniform vec3 uSkydomeCenter;

attribute vec2 uv0;

varying vec4 vPosition;
varying vec4 vUVYLength;

void main(void)
{
    gl_Position = vPosition = ftransform();
    
    vec3 objectSpacePosition = (uWorld * vPosition).xyz - uSkydomeCenter;
    
    vUVYLength.xy = uv0;
    vUVYLength.z = objectSpacePosition.y;
    vUVYLength.w = length(objectSpacePosition);
}