public Color ShadeHit(Comps comps, int remaining = 5)
{
var result = Color.Black;
foreach (var light in this.Lights)
{
var surface = comps.Object.Material.Lighting(
comps.Object,
light,
comps.OverPoint,
comps.Eye,
comps.Normal,
light.IntensityAt(comps.OverPoint, this));
var reflected = this.ReflectedColor(comps, remaining);
var refracted = this.RefractedColor(comps, remaining);
var material = comps.Object.Material;
if (material.Reflective > 0 && material.Transparency > 0)
{
var reflectance = comps.Schlick();
result += surface + reflected * reflectance + refracted * (1 - reflectance);
}
else
{
result += surface + reflected + refracted;
}
}
return(result);
}
public Color RefractedColor(Comps comps, int remaining = 5)
{
if (remaining < 1 || comps.Object.Material.Transparency == 0)
{
return(Color.Black);
}
// Find the ratio of first index of refraction to the second.
// (Yup, this is inverted from the definition of Snell's Law.)
var n_ratio = comps.n1 / comps.n2;
// cos(theta_i) is the same as the dot product of the two vectors
var cos_i = comps.Eye.Dot(comps.Normal);
// Find sin(theta_t)^2 via trigonometric identity
var sin2_t = n_ratio * n_ratio * (1 - cos_i * cos_i);
if (sin2_t > 1)
{
return(Color.Black);
}
Interlocked.Increment(ref Stats.SecondaryRays);
// Find cos(theta_t) via trigonometric identity
var cos_t = Math.Sqrt(1.0 - sin2_t);
// Compute the direction of the refracted ray
var direction = comps.Normal * (n_ratio * cos_i - cos_t) - comps.Eye * n_ratio;
// Create the refracted ray
var refract_ray = new Ray(comps.UnderPoint, direction, RayType.Refraction);
// Find the color of the refracted ray, making sure to multiply
// by the transparency value to account for any opacity
return(this.ColorAt(refract_ray, remaining - 1) * comps.Object.Material.Transparency);
}
public Color ReflectedColor(Comps comps, int remaining = 5)
{
if (remaining < 1 || comps.Object.Material.Reflective == 0)
{
return(Color.Black);
}
var specularComp = Color.White;
if (comps.Object.Material.SpecularMap != null)
{
specularComp = comps.Object.Material.SpecularMap.PatternAtShape(comps.Object, comps.OverPoint);
}
Interlocked.Increment(ref Stats.SecondaryRays);
var reflectRay = new Ray(comps.OverPoint, comps.Reflect, RayType.Reflection);
var color = this.ColorAt(reflectRay, remaining - 1);
return(color * comps.Object.Material.Reflective * specularComp);
}
