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 Intersection(DifferentialGeometry dg, Primitive primitive,
Transform objectToWorld, Transform worldToObject,
float rayEpsilon)
{
_dg = dg;
_primitive = primitive;
WorldToObject = worldToObject;
ObjectToWorld = objectToWorld;
_rayEpsilon = rayEpsilon;
}
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;
}
protected static DifferentialGeometry Bump(Texture<float> d,
DifferentialGeometry dgGeom,
DifferentialGeometry dgs)
{
// Compute offset positions and evaluate displacement texture
DifferentialGeometry dgEval = dgs;
// Shift _dgEval_ _du_ in the $u$ direction
float du = .5f * (Math.Abs(dgs.DuDx) + Math.Abs(dgs.DuDy));
if (du == 0.0f)
du = .01f;
dgEval.Point = dgs.Point + du * dgs.DpDu;
dgEval.U = dgs.U + du;
dgEval.Normal = Normal.Normalize((Normal) Vector.Cross(dgs.DpDu, dgs.DpDv) +
du * dgs.DnDu);
float uDisplace = d.Evaluate(dgEval);
// Shift _dgEval_ _dv_ in the $v$ direction
float dv = .5f * (Math.Abs(dgs.DvDx) + Math.Abs(dgs.DvDy));
if (dv == 0.0f)
dv = .01f;
dgEval.Point = dgs.Point + dv * dgs.DpDv;
dgEval.U = dgs.U;
dgEval.V = dgs.V + dv;
dgEval.Normal = Normal.Normalize((Normal) Vector.Cross(dgs.DpDu, dgs.DpDv) + dv * dgs.DnDv);
float vDisplace = d.Evaluate(dgEval);
float displace = d.Evaluate(dgs);
// Compute bump-mapped differential geometry
var dgBump = dgs.Clone();
dgBump.DpDu = dgs.DpDu + (uDisplace - displace) / du * (Vector)dgs.Normal +
displace * (Vector)dgs.DnDu;
dgBump.DpDv = dgs.DpDv + (vDisplace - displace) / dv * (Vector)dgs.Normal +
displace * (Vector)dgs.DnDv;
dgBump.Normal = (Normal) Vector.Normalize(Vector.Cross(dgBump.DpDu, dgBump.DpDv));
if (dgs.Shape.ReverseOrientation ^ dgs.Shape.TransformSwapsHandedness)
dgBump.Normal *= -1.0f;
// Orient shading normal to match geometric normal
dgBump.Normal = Normal.FaceForward(dgBump.Normal, dgGeom.Normal);
return dgBump;
}
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 Bsdf GetBsdf(DifferentialGeometry dgGeom, DifferentialGeometry dgShading)
{
// Allocate _BSDF_, possibly doing bump mapping with _bumpMap_
var dgs = (_bumpMap != null)
? Bump(_bumpMap, dgGeom, dgShading)
: dgShading;
var bsdf = new Bsdf(dgs, dgGeom.Normal);
// Evaluate textures for _MatteMaterial_ material and allocate BRDF
Spectrum r = Spectrum.Clamp(_kd.Evaluate(dgs));
float sig = MathUtility.Clamp(_sigma.Evaluate(dgs), 0.0f, 90.0f);
if (!r.IsBlack)
{
if (sig == 0.0f)
bsdf.Add(new Lambertian(r));
else
bsdf.Add(new OrenNayar(r, sig));
}
return bsdf;
}
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 virtual DifferentialGeometry GetShadingGeometry(
Transform objectToWorld, DifferentialGeometry dg)
{
return(dg);
}
public virtual bool TryIntersect(Ray ray,
out float tHit, out float rayEpsilon,
out DifferentialGeometry dg)
{
throw new InvalidOperationException("Unimplemented Shape.TryIntersect() method called.");
}
public override Bssrdf GetBssrdf(DifferentialGeometry dg, Transform objectToWorld)
{
var dgs = _shape.GetShadingGeometry(objectToWorld, dg);
return _material.GetBssrdf(dg, dgs);
}
public abstract Bsdf GetBsdf(DifferentialGeometry dgGeom, DifferentialGeometry dgShading);
public virtual DifferentialGeometry GetShadingGeometry(
Transform objectToWorld, DifferentialGeometry dg)
{
return dg;
}
public virtual bool TryIntersect(Ray ray,
out float tHit, out float rayEpsilon,
out DifferentialGeometry dg)
{
throw new InvalidOperationException("Unimplemented Shape.TryIntersect() method called.");
}
public virtual Bssrdf GetBssrdf(DifferentialGeometry dgGeom, DifferentialGeometry dgShading)
{
return null;
}
public abstract Bssrdf GetBssrdf(DifferentialGeometry dg, Transform objectToWorld);
public override Bssrdf GetBssrdf(DifferentialGeometry dg, Transform objectToWorld)
{
return null;
}
public override Bssrdf GetBssrdf(DifferentialGeometry dg, Transform objectToWorld)
{
throw new InvalidOperationException("Aggregate.GetBssrdf() method called; should have gone to GeometricPrimitive.");
}
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 sphere hit
float u = phi / _phiMax;
float theta = MathUtility.Acos(MathUtility.Clamp(phit.Z / _radius, -1.0f, 1.0f));
float v = (theta - _thetaMin) / (_thetaMax - _thetaMin);
// Compute sphere $\dpdu$ and $\dpdv$
float zradius = MathUtility.Sqrt(phit.X * phit.X + phit.Y * phit.Y);
float invzradius = 1.0f / zradius;
float cosphi = phit.X * invzradius;
float sinphi = phit.Y * invzradius;
var dpdu = new Vector(-_phiMax * phit.Y, _phiMax * phit.X, 0);
var dpdv = (_thetaMax - _thetaMin) *
new Vector(phit.Z * cosphi, phit.Z * sinphi, -_radius * MathUtility.Sin(theta));
// Compute sphere $\dndu$ and $\dndv$
Vector d2Pduu = -_phiMax * _phiMax * new Vector(phit.X, phit.Y, 0);
Vector d2Pduv = (_thetaMax - _thetaMin) * phit.Z * _phiMax * new Vector(-sinphi, cosphi, 0.0f);
Vector d2Pdvv = -(_thetaMax - _thetaMin) * (_thetaMax - _thetaMin) * new Vector(phit.X, phit.Y, phit.Z);
// 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 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 sphere hit
float u = phi / _phiMax;
float theta = MathUtility.Acos(MathUtility.Clamp(phit.Z / _radius, -1.0f, 1.0f));
float v = (theta - _thetaMin) / (_thetaMax - _thetaMin);
// Compute sphere $\dpdu$ and $\dpdv$
float zradius = MathUtility.Sqrt(phit.X * phit.X + phit.Y * phit.Y);
float invzradius = 1.0f / zradius;
float cosphi = phit.X * invzradius;
float sinphi = phit.Y * invzradius;
var dpdu = new Vector(-_phiMax * phit.Y, _phiMax * phit.X, 0);
var dpdv = (_thetaMax - _thetaMin) *
new Vector(phit.Z * cosphi, phit.Z * sinphi, -_radius * MathUtility.Sin(theta));
// Compute sphere $\dndu$ and $\dndv$
Vector d2Pduu = -_phiMax * _phiMax * new Vector(phit.X, phit.Y, 0);
Vector d2Pduv = (_thetaMax - _thetaMin) * phit.Z * _phiMax * new Vector(-sinphi, cosphi, 0.0f);
Vector d2Pdvv = -(_thetaMax - _thetaMin) * (_thetaMax - _thetaMin) * new Vector(phit.X, phit.Y, phit.Z);
// 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;
}
