Color shade(Hit hit)
{
// if no scObject was hit, return background color
if (hit.scObject == null)
return background;
Color color = new Color(0,0,0);
for(int i=0; i<numLights; i++){
// convenience for cleaner code
Vector liPos = lights[i].position;
// ambient reflection
color = color + hit.scObject.ambient * lights[i].ambient;
Vector p = hit.HitPoint();
Vector v = eye - p;
Vector s = liPos - p;
Vector m = hit.scObject.Normal(p);
// make sure light hits the front face
if (Vector.Dot(s, m) < 0) continue;
// cast a "shadow feeler" and find its closest hit position to light source
Hit feeler = intersect(liPos, p - liPos);
Vector feelerHit = feeler.HitPoint();
// check that point is less 90 degrees therefore it is on the same side of light source as displayed point
float dotLiFeel_LiPoint = Vector.Dot((liPos - feelerHit), liPos - p);
bool correctLightSide = dotLiFeel_LiPoint >= 0;
// check that the point is not the same point as the displayed point
// and if it is closer to light source or further away
float squaredLen_LiFeel = Vector.Dot((liPos - feelerHit), liPos - feelerHit);
bool beforeObj = Math.Abs(dotLiFeel_LiPoint - squaredLen_LiFeel) < 0.0001; //0.0001 to stop float round error for <=
//if there is a collision and it is closer than the displayed scObject and it is on the same side of light as scObject
if( (feeler.t<=0) || ((beforeObj) && (correctLightSide)) ){
//diffuse reflection
color = color + ( (hit.scObject.diffuse * lights[i].diffuse) * ( Vector.Dot(s, m) / Convert.ToSingle( (Math.Sqrt(Vector.Dot(s, s))*Math.Sqrt(Vector.Dot(m, m))) ) ));
//specular reflection
//h = normalized(normalized(s) + normalized(v))
Vector h = s.Normalize() + v.Normalize();
h = h.Normalize();
color = color + ( (hit.scObject.specular * lights[i].specular) * Convert.ToSingle( (Math.Pow(( Vector.Dot(h, m) / (Math.Sqrt(Vector.Dot(h, h))*Math.Sqrt(Vector.Dot(m, m))) ), hit.scObject.shininess) ) ));
}
}
return color;
}
Hit intersect(Vector source, Vector d)
{
// initially hit scObject==NULL (no hit)
Hit hit = new Hit(source, d, -1f, null);
// for every scObject, check if ray hits it
for(int i=0; i<numObjects; i++) {
float t = sceneObjects[i].Intersect(source, d);
// 1. only use hits visible for the camera
// 2. only overwrite hit if either there is
// no hit yet, or the hit is closer
if(t>0.00001 && (hit.scObject==null || t<hit.t))
hit = new Hit(source, d, t, sceneObjects[i]);
}
return hit;
}