/**
 * DOC_TBA
 *
 * @name czm_eyeOffset
 * @glslFunction
 *
 * @param {vec4} positionEC DOC_TBA.
 * @param {vec3} eyeOffset DOC_TBA.
 *
 * @returns {vec4} DOC_TBA.
 */
vec4 czm_eyeOffset(vec4 positionEC, vec3 eyeOffset)
{
    // This equation is approximate in x and y.
    vec4 p = positionEC;
    vec4 zEyeOffset = normalize(p) * eyeOffset.z;
    p.xy += eyeOffset.xy + zEyeOffset.xy;
    p.z += zEyeOffset.z;
    return p;
}