public RtColor ShadeHit(Computations computations, int remaining)
{
var colorTotal = RtColor.Black;
foreach (var light in Lights)
{
// var inShadow = IsShadowed(light.Position, computations.OverPosition);
var intensity = light.IntensityAt(computations.OverPosition, this);
var surface = computations.Shape.Material.Lighting(
computations,
light,
intensity);
var reflected = ReflectedColor(computations, remaining);
var refracted = RefractedColor(computations, remaining);
var material = computations.Shape.Material;
if (material.Reflective > 0 && material.Transparency > 0)
{
var reflectance = computations.Schlick();
colorTotal += surface + reflected * reflectance + refracted * (1 - reflectance);
}
else
{
colorTotal += surface + reflected + refracted;
}
}
return(colorTotal);
}
public RtColor ReflectedColor(Computations computations, int remaining)
{
if (computations.Shape.Material.Reflective == 0 || remaining <= 0)
{
return(RtColor.Black);
}
var reflectRay = new Ray(computations.OverPosition, computations.ReflectVector);
var reflectColor = ColorAt(reflectRay, remaining - 1);
return(reflectColor * computations.Shape.Material.Reflective);
}
public RtColor Lighting(Computations computations, Light light, double intensity)
{
var color = Color;
if (Pattern != null)
{
color = Pattern.PatternAtShape(computations.Shape, computations.OverPosition);
}
var effectiveColor = color * light.Intensity;
var ambient = effectiveColor * Ambient;
// var lightPosition = light.Position;
RtColor sum = RtColor.Black;
foreach (var lightPosition in light.GetSamples())
{
var lightVector = (lightPosition - computations.Position).Normalize();
var lightDotNormal = lightVector.Dot(computations.NormalVector);
if (lightDotNormal < 0 || intensity == 0)
{
continue;
}
sum += effectiveColor * Diffuse * lightDotNormal;
var reflectVector = lightVector.Negate().Reflect(computations.NormalVector);
var reflectDotEye = reflectVector.Dot(computations.EyeVector);
if (reflectDotEye > 0)
{
var factor = Math.Pow(reflectDotEye, Shininess);
sum += light.Intensity * Specular * factor;
}
}
var results = ambient + (sum / light.Samples) * intensity;
return(results);
}
public RtColor RefractedColor(Computations computations, int remaining)
{
if (computations.Shape.Material.Transparency == 0 || remaining == 0)
{
return(RtColor.Black);
}
var nRatio = computations.n1 / computations.n2;
var cosi = computations.EyeVector.Dot(computations.NormalVector);
var sin2t = Math.Pow(nRatio, 2) * (1 - Math.Pow(cosi, 2));
if (sin2t > 1)
{
return(RtColor.Black);
}
var cost = Math.Sqrt(1.0 - sin2t);
var direction = computations.NormalVector * (nRatio * cosi - cost) - computations.EyeVector * nRatio;
var refractRay = new Ray(computations.UnderPosition, direction);
var color = ColorAt(refractRay, remaining - 1) * computations.Shape.Material.Transparency;
return(color);
}
public Computations PrepareComputations(Ray ray, IntersectionList intersections)
{
var computations = new Computations()
{
Time = Time,
Shape = Shape,
Position = ray.Position(Time),
EyeVector = ray.Direction.Negate(),
};
computations.NormalVector = Shape.NormalAt(computations.Position, this);
if(computations.NormalVector.Dot(computations.EyeVector) < 0)
{
computations.Inside = true;
computations.NormalVector = computations.NormalVector.Negate();
}
else
{
computations.Inside = false;
}
computations.ReflectVector = ray.Direction.Reflect(computations.NormalVector);
List<Shape> container = new List<Shape>();
if(intersections != null && intersections.Count > 0)
{
foreach (var intersection in intersections.Items)
{
if (intersection == this)
{
if (container.Count == 0)
{
computations.n1 = 1.0;
}
else
{
computations.n1 = container.Last().Material.RefractiveIndex;
}
}
if (container.Contains(intersection.Shape))
{
container.Remove(intersection.Shape);
}
else
{
container.Add(intersection.Shape);
}
if (intersection == this)
{
if (container.Count == 0)
{
computations.n2 = 1.0;
}
else
{
computations.n2 = container.Last().Material.RefractiveIndex;
}
break;
}
}
}
return computations;
}
