/**
 * Computes the point along a ray at the given time.  <code>time</code> can be positive, negative, or zero.
 *
 * @name czm_pointAlongRay
 * @glslFunction
 *
 * @param {czm_ray} ray The ray to compute the point along.
 * @param {float} time The time along the ray.
 * 
 * @returns {vec3} The point along the ray at the given time.
 * 
 * @example
 * czm_ray ray = czm_ray(vec3(0.0), vec3(1.0, 0.0, 0.0)); // origin, direction
 * vec3 v = czm_pointAlongRay(ray, 2.0); // (2.0, 0.0, 0.0)
 */
vec3 czm_pointAlongRay(czm_ray ray, float time)
{
    return ray.origin + (time * ray.direction);
}