func DiffusePhoton(scene []*geometry.Shape, emitter *geometry.Shape, ray geometry.Ray, colour geometry.Vec3, result chan<- PhotonHit, alpha geometry.Float, depth int, rand *rand.Rand) {
if geometry.Float(rand.Float32()) > alpha {
return
}
if shape, distance := ClosestIntersection(scene, ray); shape != nil {
impact := ray.Origin.Add(ray.Direction.Mult(distance))
if depth == 0 && emitter == shape {
// Leave the emitter first
nextRay := geometry.Ray{impact, ray.Direction}
DiffusePhoton(scene, emitter, nextRay, colour, result, alpha, depth, rand)
} else {
normal := shape.NormalDir(impact).Normalize()
reverse := ray.Direction.Mult(-1)
outgoing := normal
if normal.Dot(reverse) < 0 {
outgoing = normal.Mult(-1)
}
strength := colour.Mult(alpha / (1 + distance))
result <- PhotonHit{impact, strength, ray.Direction, uint8(depth)}
if shape.Material == geometry.DIFFUSE {
// Random bounce for color bleeding
u := normal.Cross(reverse).Normalize().Mult(geometry.Float(rand.NormFloat64() * 0.5))
v := u.Cross(normal).Normalize().Mult(geometry.Float(rand.NormFloat64() * 0.5))
bounce := geometry.Vec3{
u.X + outgoing.X + v.X,
u.Y + outgoing.Y + v.Y,
u.Z + outgoing.Z + v.Z,
}
bounceRay := geometry.Ray{impact, bounce.Normalize()}
bleedColour := colour.MultVec(shape.Colour).Mult(alpha / (1 + distance))
DiffusePhoton(scene, shape, bounceRay, bleedColour, result, alpha*0.66, depth+1, rand)
}
// Store Shadow Photons
shadowRay := geometry.Ray{impact, ray.Direction}
DiffusePhoton(scene, shape, shadowRay, geometry.Vec3{0, 0, 0}, result, alpha*0.66, depth+1, rand)
}
}
}
func PhotonChunk(scene []*geometry.Shape, traceFunc RayFunc, shape *geometry.Shape, factor, start, chunksize int, result chan<- PhotonHit, done chan<- bool, rand *rand.Rand) {
for i := 0; i < chunksize; i++ {
longitude := (start*chunksize + i) / factor
latitude := (start*chunksize + i) % factor
//fmt.Println("Lo La:", longitude, latitude)
sign := -2.0*float64(longitude%2.0) + 1.0
phi := 2.0 * math.Pi * float64(longitude) / float64(factor)
theta := math.Pi * float64(latitude) / float64(factor)
//fmt.Println("S, T, P:", sign, theta, phi)
x, y, z := math.Sin(theta)*math.Cos(phi),
sign*math.Cos(theta),
math.Sin(theta)*math.Sin(phi)
direction := geometry.Vec3{geometry.Float(x), geometry.Float(y), geometry.Float(z)}
ray := geometry.Ray{shape.Position, direction.Normalize()}
traceFunc(scene, shape, ray, shape.Emission, result, 1.0, 0, rand)
}
done <- true
}
func Radiance(ray geometry.Ray, scene *geometry.Scene, diffuseMap /*, causticsMap*/ *kd.KDNode, depth int, alpha float64, rand *rand.Rand) geometry.Vec3 {
if depth > Config.MinDepth && rand.Float64() > alpha {
return geometry.Vec3{0, 0, 0}
}
if shape, distance := ClosestIntersection(scene.Objects, ray); shape != nil {
impact := ray.Origin.Add(ray.Direction.Mult(distance))
normal := shape.NormalDir(impact).Normalize()
reverse := ray.Direction.Mult(-1)
contribution := shape.Emission
outgoing := normal
if normal.Dot(reverse) < 0 {
outgoing = normal.Mult(-1)
}
if shape.Material == geometry.DIFFUSE {
var /*causticLight,*/ directLight geometry.Vec3
/*nodes := causticsMap.Neighbors(impact, 0.1)
for _, e := range nodes {
photon := causticPhotons[e.Position]
dist := photon.Location.Distance(impact)
light := photon.Photon.Mult(outgoing.Dot(photon.Incomming.Mult(-1 / math.Pi * (1 + dist))))
causticLight.AddInPlace(light)
}
if len(nodes) > 0 {
causticLight = causticLight.Mult(1.0 / float64(len(nodes)))
}*/
directLight = EmitterSampling(impact, normal, scene.Objects, rand)
u := normal.Cross(reverse).Normalize().Mult(geometry.Float(rand.NormFloat64() * 0.5))
v := u.Cross(normal).Normalize().Mult(geometry.Float(rand.NormFloat64() * 0.5))
bounceDirection := geometry.Vec3{
u.X + outgoing.X + v.X,
u.Y + outgoing.Y + v.Y,
u.Z + outgoing.Z + v.Z,
}
bounceRay := geometry.Ray{impact, bounceDirection.Normalize()}
indirectLight := Radiance(bounceRay, scene, diffuseMap /*causticsMap,*/, depth+1, alpha*0.9, rand)
dot := outgoing.Dot(reverse)
diffuseLight := geometry.Vec3{
(shape.Colour.X * (directLight.X + indirectLight.X) /*+ causticLight.X*/) * dot,
(shape.Colour.Y * (directLight.Y + indirectLight.Y) /*+ causticLight.Y*/) * dot,
(shape.Colour.Z * (directLight.Z + indirectLight.Z) /*+ causticLight.Z*/) * dot,
}
return contribution.Add(diffuseLight)
}
if shape.Material == geometry.SPECULAR {
reflectionDirection := ray.Direction.Sub(normal.Mult(2 * outgoing.Dot(ray.Direction)))
reflectedRay := geometry.Ray{impact, reflectionDirection.Normalize()}
incomingLight := Radiance(reflectedRay, scene, diffuseMap /*causticsMap,*/, depth+1, alpha*0.99, rand)
return incomingLight.Mult(outgoing.Dot(reverse))
}
if shape.Material == geometry.REFRACTIVE {
var n1, n2 float64
if normal.Dot(outgoing) < 0 {
// Leave the glass
n1, n2 = GLASS, AIR
} else {
n1, n2 = AIR, GLASS
}
factor := n1 / n2
cosTi := float64(normal.Dot(reverse))
sinTi := math.Sqrt(1 - cosTi*cosTi) // sin² + cos² = 1
sqrt := math.Sqrt(math.Max(1.0-math.Pow(factor*sinTi, 2), 0))
// Rs
top := n1*cosTi - n2*sqrt
bottom := n1*cosTi + n2*sqrt
Rs := math.Pow(top/bottom, 2)
// Rp
top = n1*sqrt - n2*cosTi
bottom = n1*sqrt + n2*cosTi
Rp := math.Pow(top/bottom, 2)
R := (Rs*Rs + Rp*Rp) / 2.0
// Approximate:
R = math.Pow((n1-n2)/(n1+n2), 2)
// SmallPT formula
//R = R + (1 - R) * math.Pow(1 - cosTi, 5)
T := 1.0 - R
if math.IsNaN(R) {
fmt.Printf("into: %v, sqrt: %v\n", n2 > n1, sqrt)
fmt.Printf("cos: %v, sin: %v\n", cosTi, sinTi)
fmt.Printf("n1: %v, n2: %v\n", n1, n2)
fmt.Printf("Top: %v, Bottom: %v\n", top, bottom)
fmt.Printf("Rs: %v, Rp: %v\n", Rs, Rp)
fmt.Printf("R: %v, T: %v\n", R, T)
panic("NAN!")
}
totalReflection := false
if n1 > n2 {
maxAngle := math.Asin(n2 / n1)
actualAngle := math.Asin(sinTi)
if actualAngle > maxAngle {
totalReflection = true
}
totalReflection = totalReflection
}
if totalReflection {
reflectionDirection := ray.Direction.Sub(outgoing.Mult(2 * outgoing.Dot(ray.Direction)))
reflectedRay := geometry.Ray{impact, reflectionDirection.Normalize()}
return Radiance(reflectedRay, scene, diffuseMap /*causticsMap,*/, depth+1, alpha*0.9, rand)
} else {
reflectionDirection := ray.Direction.Sub(outgoing.Mult(2 * outgoing.Dot(ray.Direction)))
reflectedRay := geometry.Ray{impact, reflectionDirection.Normalize()}
reflectedLight := Radiance(reflectedRay, scene, diffuseMap /*causticsMap,*/, depth+1, alpha*0.9, rand).Mult(geometry.Float(R))
nDotI := float64(normal.Dot(ray.Direction))
trasmittedDirection := ray.Direction.Mult(geometry.Float(factor))
term2 := factor * nDotI
term3 := math.Sqrt(1 - factor*factor*(1-nDotI*nDotI))
trasmittedDirection = trasmittedDirection.Add(normal.Mult(geometry.Float(term2 - term3)))
transmittedRay := geometry.Ray{impact, trasmittedDirection.Normalize()}
transmittedLight := Radiance(transmittedRay, scene, diffuseMap /*causticsMap,*/, depth+1, alpha*0.9, rand).Mult(geometry.Float(T))
return reflectedLight.Add(transmittedLight).Mult(outgoing.Dot(reverse))
}
}
panic("Material without property encountered!")
}
return geometry.Vec3{0, 0, 0}
}