/// <summary>
/// Get diffuse color and specular for the hit point with a specific light
/// </summary>
/// <param name="light"></param>
/// <param name="ray"></param>
/// <param name="hit"></param>
/// <param name="specular"></param>
/// <param name="debug"></param>
/// <returns></returns>
protected Vector3 illuminateBy(Vector3 ppos, Light light, Ray ray, RayHit hit, ref Vector3 specular, bool debug)
{
// Calclulate if we are within light range
var light_vec = ppos - hit.Position;
float dist_sq = Vector3.Dot(light_vec, light_vec);
float intens_sq = light.LightCache.IntensitySq;
if (dist_sq >= intens_sq * Constants.LIGHT_DECAY)
{
return(Vector3.Zero);
}
// Create a shadow ray
var dist = (float)Math.Sqrt(dist_sq);
light_vec = light_vec / dist;
var shadow_ray = new Ray(hit.Position + (light_vec * Constants.EPSILON), light_vec);
var tmp = RayHit.Default();
foreach (var o in World.Objects)
{
if (o.Intersect(shadow_ray, ref tmp) && tmp.T < dist)
{
if (debug)
{
DebugData.ShadowRaysOccluded.Add(new Tuple <Ray, RayHit>(shadow_ray, tmp));
}
return(new Vector3());
}
}
// Diffuse
var materialColor = hit.Obj.Material.Texture == null
? hit.Obj.Material.Diffuse
: hit.Obj.Material.Texture.GetColor(hit.Obj.GetUV(hit));
var color = materialColor * Math.Max(0.0f, Vector3.Dot(hit.Normal, light_vec));
// Inverse square law
var light_powah = light.Intensity / (Constants.PI4 * dist_sq);
light_powah *= light.AngleEnergy(light_vec.Normalized());
// Specular will be used separately
if (hit.Obj.Material.IsGlossy)
{
var hardness = Math.Max(.0f, Vector3.Dot(-ray.Direction, QuickMaths.Reflect(-light_vec, hit.Normal)));
specular += light.Colour * light_powah * hit.Obj.Material.Specular *
(float)Math.Pow(hardness, hit.Obj.Material.Shinyness);
}
if (debug)
{
DebugData.ShadowRays.Add(new Tuple <Ray, Vector3>(shadow_ray, ppos));
}
return(light.Colour * color * light_powah);
}
