//calculates the color at the given 3D point using phong shading.
private Color GetObjectColor(IntersectionTester.Intersection point, Vector3 viewFrom)
{
Light light = scene.light;
Vector3 location = point.intersectionPoint;
Vector3 normal = point.intersectionNormal;
Vector3 lightDirection = (light.Pos - location);
float lightDistance = lightDirection.Length;
lightDirection = lightDirection.Normalize();
Vector3 shadowOrigin = location + 0.01f * normal;
if (IntersectionTester.GetInShadow(new Ray(shadowOrigin, lightDirection), lightDistance))
{
return(scene.ambientLight);
}
Vector3 reflect = GetReflectionVector(lightDirection, normal).Normalize();
float phongConstant = point.hitObject.phongConstant;
float colorFactor = reflect * viewFrom;
Color specular = Math.Sign(colorFactor) * (float)Math.Pow(colorFactor, phongConstant) * scene.light.Color;
Color diffuse = lightDirection * normal * point.hitObject.DiffuseColor;
return(specular + diffuse + scene.ambientLight);
}
private Color GetPixelColor(float x, float y)
{
Vector3 pixelPos = GetWorldSpacePixel(x, y);
Vector3 pixelDirection = pixelPos - cameraPos;
Ray pixelRay = new Ray(cameraPos, pixelDirection);
IntersectionTester.Intersection hit = IntersectionTester.GetClosestObject(pixelRay);
SceneObject closestObject = hit.hitObject;
if (closestObject == null)
{
return(backgroundColor);
}
return(GetColorWithReflections(hit, pixelDirection, 0));
}
//given a point and a view direction, returns the color including reflections
private Color GetColorWithReflections(IntersectionTester.Intersection point, Vector3 direction, int depth)
{
const int MAX_DEPTH = 5;
if (depth > MAX_DEPTH)
{
return(backgroundColor);
}
List <KeyValuePair <float, Color> > reflections = new List <KeyValuePair <float, Color> > {
new KeyValuePair <float, Color>(1 - point.hitObject.reflectivity, GetObjectColor(point, direction))
};
const float REFLECTION_FALLOFF = 0.9f;
float currentWeight = REFLECTION_FALLOFF * point.hitObject.reflectivity;
IntersectionTester.Intersection currentHit = point;
Vector3 currentDirection = direction;
if (currentWeight > 0.01f)
{
Vector3 reflectionVector = GetReflectionVector(currentDirection, currentHit.intersectionNormal).Normalize();
Vector3 reflectionOrigin = currentHit.intersectionPoint + 0.01f * reflectionVector;
Ray reflectionRay = new Ray(reflectionOrigin, reflectionVector);
currentHit = IntersectionTester.GetClosestObject(reflectionRay);
if (currentHit.hitObject != null)
{
reflections.Add(new KeyValuePair <float, Color>(currentWeight, GetColorWithReflections(currentHit, reflectionVector, depth + 1)));
}
else
{
reflections.Add(new KeyValuePair <float, Color>(currentWeight, backgroundColor));
}
}
return(Color.GetWeightedAverage(reflections));
}