public static float SinPhi(ref Vector w)
{
float sintheta = SinTheta(ref w);
if (sintheta == 0.0f)
return 0.0f;
return MathUtility.Clamp(w.Y / sintheta, -1.0f, 1.0f);
}
public Spectrum Le(Vector wo)
{
var areaLight = _primitive.GetAreaLight();
return (areaLight != null)
? areaLight.L(_dg.Point, _dg.Normal, wo)
: Spectrum.CreateBlack();
}
public override Spectrum F(Vector wo, Vector wi)
{
float sinthetai = ReflectionUtilities.SinTheta(ref wi);
float sinthetao = ReflectionUtilities.SinTheta(ref wo);
// Compute cosine term of Oren-Nayar model
float maxcos = 0.0f;
if (sinthetai > 1e-4 && sinthetao > 1e-4)
{
float sinphii = ReflectionUtilities.SinPhi(ref wi);
float cosphii = ReflectionUtilities.CosPhi(ref wi);
float sinphio = ReflectionUtilities.SinPhi(ref wo);
float cosphio = ReflectionUtilities.CosPhi(ref wo);
float dcos = cosphii * cosphio + sinphii * sinphio;
maxcos = Math.Max(0.0f, dcos);
}
// Compute sine and tangent terms of Oren-Nayar model
float sinalpha, tanbeta;
if (ReflectionUtilities.AbsCosTheta(ref wi) > ReflectionUtilities.AbsCosTheta(ref wo))
{
sinalpha = sinthetao;
tanbeta = sinthetai / ReflectionUtilities.AbsCosTheta(ref wi);
}
else
{
sinalpha = sinthetai;
tanbeta = sinthetao / ReflectionUtilities.AbsCosTheta(ref wo);
}
return _reflectance * MathUtility.InvPi * (_a + _b * maxcos * sinalpha * tanbeta);
}
public static Vector CosineSampleHemisphere(float u1, float u2)
{
var ret = new Vector();
ConcentricSampleDisk(u1, u2, out ret.X, out ret.Y);
ret.Z = MathUtility.Sqrt(Math.Max(0.0f, 1.0f - ret.X * ret.X - ret.Y * ret.Y));
return ret;
}
public Vector TransformVector(ref Vector v)
{
float x = v.X, y = v.Y, z = v.Z;
return new Vector(
_m.M[0, 0] * x + _m.M[0, 1] * y + _m.M[0, 2] * z,
_m.M[1, 0] * x + _m.M[1, 1] * y + _m.M[1, 2] * z,
_m.M[2, 0] * x + _m.M[2, 1] * y + _m.M[2, 2] * z);
}
public virtual Spectrum SampleF(Vector wo, out Vector wi, float u1, float u2, out float pdf)
{
// Cosine-sample the hemisphere, flipping the direction if necessary
wi = MonteCarloUtilities.CosineSampleHemisphere(u1, u2);
if (wo.Z < 0.0f) wi.Z *= -1.0f;
pdf = Pdf(wo, wi);
return F(wo, wi);
}
public static Vector Cross(Normal v1, Vector v2)
{
float v1x = v1.X, v1y = v1.Y, v1z = v1.Z;
float v2x = v2.X, v2y = v2.Y, v2z = v2.Z;
return new Vector(
(v1y * v2z) - (v1z * v2y),
(v1z * v2x) - (v1x * v2z),
(v1x * v2y) - (v1y * v2x));
}
public override Spectrum SampleL(Point p, float pEpsilon, LightSample ls,
float time, out Vector wi, out float pdf,
out VisibilityTester vis)
{
wi = _direction;
pdf = 1.0f;
vis = new VisibilityTester(p, pEpsilon, wi, time);
return _radiance;
}
public override Spectrum SampleL(
Point p, float pEpsilon, LightSample ls, float time, out Vector wi,
out float pdf, out VisibilityTester vis)
{
wi = Vector.Normalize(_lightPosition - p);
pdf = 1.0f;
vis = new VisibilityTester(p, pEpsilon, _lightPosition, 0.0f, time);
return _intensity / Point.DistanceSquared(_lightPosition, p);
}
public Bsdf(DifferentialGeometry dgShading, Normal nGeom, float eta = 1.0f)
{
_dgShading = dgShading;
_ng = nGeom;
_eta = eta;
_nn = dgShading.Normal;
_sn = Vector.Normalize(dgShading.DpDu);
_tn = Normal.Cross(_nn, _sn);
_bxdfs = new List<Bxdf>();
}
public override bool TryIntersect(Ray r, out float tHit,
out float rayEpsilon, out DifferentialGeometry dg)
{
tHit = float.NegativeInfinity;
rayEpsilon = 0.0f;
dg = null;
float phi;
Point phit;
float thit;
if (!DoIntersection(r, out phi, out phit, out thit))
return false;
// Find parametric representation of cylinder hit
float u = phi / _phiMax;
float v = (phit.Z - _zMin) / (_zMax - _zMin);
// Compute cylinder $\dpdu$ and $\dpdv$
var dpdu = new Vector(-_phiMax * phit.Y, _phiMax * phit.X, 0);
var dpdv = new Vector(0, 0, _zMax - _zMin);
// Compute cylinder $\dndu$ and $\dndv$
Vector d2Pduu = -_phiMax * _phiMax * new Vector(phit.X, phit.Y, 0);
Vector d2Pduv = Vector.Zero, d2Pdvv = Vector.Zero;
// Compute coefficients for fundamental forms
float E = Vector.Dot(dpdu, dpdu);
float F = Vector.Dot(dpdu, dpdv);
float G = Vector.Dot(dpdv, dpdv);
Vector N = Vector.Normalize(Vector.Cross(dpdu, dpdv));
float e = Vector.Dot(N, d2Pduu);
float f = Vector.Dot(N, d2Pduv);
float g = Vector.Dot(N, d2Pdvv);
// Compute $\dndu$ and $\dndv$ from fundamental form coefficients
float invEGF2 = 1.0f / (E * G - F * F);
var dndu = (Normal) ((f * F - e * G) * invEGF2 * dpdu +
(e * F - f * E) * invEGF2 * dpdv);
var dndv = (Normal) ((g * F - f * G) * invEGF2 * dpdu +
(f * F - g * E) * invEGF2 * dpdv);
// Initialize _DifferentialGeometry_ from parametric information
var o2w = ObjectToWorld;
dg = new DifferentialGeometry(o2w.TransformPoint(ref phit),
o2w.TransformVector(ref dpdu), o2w.TransformVector(ref dpdv),
o2w.TransformNormal(ref dndu), o2w.TransformNormal(ref dndv),
u, v, this);
// Update _tHit_ for quadric intersection
tHit = thit;
// Compute _rayEpsilon_ for quadric intersection
rayEpsilon = 5e-4f * tHit;
return true;
}
public PerspectiveCamera(
AnimatedTransform cameraToWorld, float[] screenWindow,
float shutterOpen, float shutterClose,
float lensRadius, float focalDistance,
float fieldOfView,
Film film)
: base(cameraToWorld, Transform.Perspective(fieldOfView, 1e-2f, 1000.0f), screenWindow, shutterOpen, shutterClose, lensRadius, focalDistance, film)
{
// Compute differential changes in origin for perspective camera rays
_dxCamera = RasterToCamera.TransformPoint(new Point(1, 0, 0)) - RasterToCamera.TransformPoint(new Point(0, 0, 0));
_dyCamera = RasterToCamera.TransformPoint(new Point(0, 1, 0)) - RasterToCamera.TransformPoint(new Point(0, 0, 0));
}
public virtual Spectrum Rho(Vector wo, int numSamples, float[] samples)
{
Spectrum r = Spectrum.CreateBlack();
for (int i = 0; i < numSamples; ++i)
{
// Estimate one term of $\rho_\roman{hd}$
Vector wi;
float pdf;
Spectrum f = SampleF(wo, out wi, samples[2 * i], samples[2 * i + 1], out pdf);
if (pdf > 0.0f) r += f * ReflectionUtilities.AbsCosTheta(ref wi) / pdf;
}
return r / numSamples;
}
public virtual float Pdf(Point p, Vector wi)
{
// Intersect sample ray with area light geometry
var ray = new Ray(p, wi, 1e-3f);
ray.Depth = -1; // temporary hack to ignore alpha mask
float thit, rayEpsilon;
DifferentialGeometry dgLight;
if (!TryIntersect(ray, out thit, out rayEpsilon, out dgLight))
return 0.0f;
// Convert light sample weight to solid angle measure
float pdf = Point.DistanceSquared(p, ray.Evaluate(thit)) / (Normal.AbsDot(dgLight.Normal, -wi) * Area);
if (float.IsInfinity(pdf))
pdf = 0.0f;
return pdf;
}
public DifferentialGeometry(Point point, Vector dpdu, Vector dpdv,
Normal dndu, Normal dndv, float u, float v, Shape shape)
{
Point = point;
Normal = (Normal) Vector.Normalize(Vector.Cross(dpdu, dpdv));
DpDu = dpdu;
DpDv = dpdv;
DnDu = dndu;
DnDv = dndv;
U = u;
V = v;
Shape = shape;
if (shape != null && shape.ReverseOrientation != shape.TransformSwapsHandedness)
Normal *= -1.0f;
}
private static void Decompose(Matrix4x4 m, out Vector t, out Quaternion r, out Matrix4x4 s)
{
// Extract translation _T_ from transformation matrix
t.X = m.M[0, 3];
t.Y = m.M[1, 3];
t.Z = m.M[2, 3];
// Compute new transformation matrix _M_ without translation
Matrix4x4 M = m.Clone();
for (int i = 0; i < 3; ++i)
M.M[i, 3] = M.M[3, i] = 0.0f;
M.M[3, 3] = 1.0f;
// Extract rotation _R_ from transformation matrix
float norm;
int count = 0;
Matrix4x4 R = M.Clone();
do
{
// Compute next matrix _Rnext_ in series
var Rnext = new Matrix4x4();
var Rit = Matrix4x4.Invert(Matrix4x4.Transpose(R));
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j)
Rnext.M[i, j] = 0.5f * (R.M[i, j] + Rit.M[i, j]);
// Compute norm of difference between _R_ and _Rnext_
norm = 0.0f;
for (int i = 0; i < 3; ++i)
{
float n = Math.Abs(R.M[i, 0] - Rnext.M[i, 0]) +
Math.Abs(R.M[i, 1] - Rnext.M[i, 1]) +
Math.Abs(R.M[i, 2] - Rnext.M[i, 2]);
norm = Math.Max(norm, n);
}
R = Rnext;
} while (++count < 100 && norm > .0001f);
// XXX TODO FIXME deal with flip...
r = (Quaternion) new Transform(R);
// Compute scale _S_ using rotation and original matrix
s = Matrix4x4.Mul(Matrix4x4.Invert(R), M);
}
public override bool TryIntersect(Ray r, out float tHit,
out float rayEpsilon, out DifferentialGeometry dg)
{
tHit = float.NegativeInfinity;
rayEpsilon = 0.0f;
dg = null;
float phi, dist2, thit;
Point phit;
if (!DoIntersection(r, out phi, out dist2, out phit, out thit))
return false;
// Find parametric representation of disk hit
float u = phi / _phiMax;
float oneMinusV = ((MathUtility.Sqrt(dist2) - _innerRadius) / (_radius - _innerRadius));
float invOneMinusV = (oneMinusV > 0.0f) ? (1.0f / oneMinusV) : 0.0f;
float v = 1.0f - oneMinusV;
var dpdu = new Vector(-_phiMax * phit.Y, _phiMax * phit.X, 0.0f);
var dpdv = new Vector(-phit.X * invOneMinusV, -phit.Y * invOneMinusV, 0.0f);
dpdu *= _phiMax * MathUtility.InvTwoPi;
dpdv *= (_radius - _innerRadius) / _radius;
Normal dndu = Normal.Zero, dndv = Normal.Zero;
// Initialize _DifferentialGeometry_ from parametric information
var o2w = ObjectToWorld;
dg = new DifferentialGeometry(o2w.TransformPoint(ref phit),
o2w.TransformVector(ref dpdu), o2w.TransformVector(ref dpdv),
o2w.TransformNormal(ref dndu), o2w.TransformNormal(ref dndv),
u, v, this);
// Update _tHit_ for quadric intersection
tHit = thit;
// Compute _rayEpsilon_ for quadric intersection
rayEpsilon = 5e-4f * tHit;
return true;
}
public override Spectrum L(Point p, Normal n, Vector w)
{
throw new System.NotImplementedException();
}
public override float Pdf(Point p, Vector wi)
{
throw new System.NotImplementedException();
}
public override Spectrum SampleL(Point p, float pEpsilon, LightSample ls, float time, out Vector wi, out float pdf,
out VisibilityTester vis)
{
throw new System.NotImplementedException();
}
public static Normal FaceForward(Normal n, Vector v)
{
return (Dot(n, v) < 0.0f) ? -n : n;
}
public static float Dot(Vector v1, Normal v2)
{
return v1.X * v2.X + v1.Y * v2.Y + v1.Z * v2.Z;
}
public static float Dot(Normal n1, Vector n2)
{
return n1.X * n2.X + n1.Y * n2.Y + n1.Z * n2.Z;
}
public static Vector SphericalDirection(
float sintheta, float costheta, float phi,
Vector x, Vector y, Vector z)
{
return sintheta * MathUtility.Cos(phi) * x
+ sintheta * MathUtility.Sin(phi) * y
+ costheta * z;
}
public void ComputeDifferentials(RayDifferential ray)
{
if (ray.HasDifferentials)
{
// Estimate screen space change in $\pt{}$ and $(u,v)$
// Compute auxiliary intersection points with plane
float d = -Normal.Dot(Normal, new Vector(Point.X, Point.Y, Point.Z));
var rxv = new Vector(ray.RxOrigin.X, ray.RxOrigin.Y, ray.RxOrigin.Z);
float tx = -(Normal.Dot(Normal, rxv) + d) / Normal.Dot(Normal, ray.RxDirection);
if (float.IsNaN(tx))
throw new InvalidOperationException();
Point px = ray.RxOrigin + tx * ray.RxDirection;
var ryv = new Vector(ray.RyOrigin.X, ray.RyOrigin.Y, ray.RyOrigin.Z);
float ty = -(Normal.Dot(Normal, ryv) + d) / Normal.Dot(Normal, ray.RyDirection);
if (float.IsNaN(ty))
throw new InvalidOperationException();
Point py = ray.RyOrigin + ty * ray.RyDirection;
DpDx = px - Point;
DpDy = py - Point;
// Compute $(u,v)$ offsets at auxiliary points
// Initialize _A_, _Bx_, and _By_ matrices for offset computation
var A = new float[2, 2];
var Bx = new float[2];
var By = new float[2];
var axes = new int[2];
if (Math.Abs(Normal.X) > Math.Abs(Normal.Y) && Math.Abs(Normal.X) > Math.Abs(Normal.Z))
{
axes[0] = 1;
axes[1] = 2;
}
else if (Math.Abs(Normal.Y) > Math.Abs(Normal.Z))
{
axes[0] = 0;
axes[1] = 2;
}
else
{
axes[0] = 0;
axes[1] = 1;
}
// Initialize matrices for chosen projection plane
A[0, 0] = DpDu[axes[0]];
A[0, 1] = DpDv[axes[0]];
A[1, 0] = DpDu[axes[1]];
A[1, 1] = DpDv[axes[1]];
Bx[0] = px[axes[0]] - Point[axes[0]];
Bx[1] = px[axes[1]] - Point[axes[1]];
By[0] = py[axes[0]] - Point[axes[0]];
By[1] = py[axes[1]] - Point[axes[1]];
if (!Matrix4x4.SolveLinearSystem2x2(A, Bx, out DuDx, out DvDx))
{
DuDx = 0.0f;
DvDx = 0.0f;
}
if (!Matrix4x4.SolveLinearSystem2x2(A, By, out DuDy, out DvDy))
{
DuDy = 0.0f;
DvDy = 0.0f;
}
}
else
{
DuDx = DvDx = 0.0f;
DuDy = DvDy = 0.0f;
DpDx = DpDy = Vector.Zero;
}
}
public static float SphericalTheta(Vector v)
{
return MathUtility.Acos(MathUtility.Clamp(v.Z, -1.0f, 1.0f));
}
public static Vector UniformSampleCone(
float u1, float u2, float costhetamax,
ref Vector x, ref Vector y, ref Vector z)
{
float costheta = MathUtility.Lerp(u1, costhetamax, 1.0f);
float sintheta = MathUtility.Sqrt(1.0f - costheta * costheta);
float phi = u2 * 2.0f * MathUtility.Pi;
return MathUtility.Cos(phi) * sintheta * x + MathUtility.Sin(phi) * sintheta * y + costheta * z;
}
public Vector TransformVector(float time, Vector v)
{
if (!_actuallyAnimated || time <= _startTime)
return _startTransform.TransformVector(ref v);
if (time >= _endTime)
return _endTransform.TransformVector(ref v);
Transform t;
Interpolate(time, out t);
return t.TransformVector(ref v);
}
public static float AbsDot(Normal v1, Vector v2)
{
return Math.Abs(Dot(v1, v2));
}
public static float SphericalPhi(Vector v)
{
float p = MathUtility.Atan2(v.Y, v.X);
return (p < 0.0f) ? p + 2.0f * MathUtility.Pi : p;
}
