bool Disk::Intersect(const Ray &r, float *tHit, float *rayEpsilon, DifferentialGeometry *dg) const { // Transform _Ray_ to object space Ray ray; (*WorldToObject)(r, &ray); // Compute plane intersection for disk if (fabsf(ray.d.z) < 1e-7) return false; float thit = (height - ray.o.z) / ray.d.z; if (thit < ray.mint || thit > ray.maxt) return false; // See if hit point is inside disk radii and $\phimax$ Point phit = ray(thit); float dist2 = phit.x * phit.x + phit.y * phit.y; if (dist2 > radius * radius || dist2 < innerRadius * innerRadius) return false; // Test disk $\phi$ value against $\phimax$ float phi = atan2f(phit.y, phit.x); if (phi < 0) phi += 2. * M_PI; if (phi > phiMax) return false; // Find parametric representation of disk hit float u = phi / phiMax; float v = 1.f - ((sqrtf(dist2)-innerRadius) / (radius-innerRadius)); Vector dpdu(-phiMax * phit.y, phiMax * phit.x, 0.); Vector dpdv(-phit.x / (1-v), -phit.y / (1-v), 0.); dpdu *= phiMax * INV_TWOPI; dpdv *= (radius - innerRadius) / radius; Normal dndu(0,0,0), dndv(0,0,0); // Initialize _DifferentialGeometry_ from parametric information *dg = DifferentialGeometry((*ObjectToWorld)(phit), (*ObjectToWorld)(dpdu), (*ObjectToWorld)(dpdv), (*ObjectToWorld)(dndu), (*ObjectToWorld)(dndv), u, v, this); // Update _tHit_ for quadric intersection *tHit = thit; // Compute _rayEpsilon_ for quadric intersection *rayEpsilon = 5e-4f * *tHit; return true; }
bool Disk::Intersect(const Ray &r, Float *tHit, SurfaceInteraction *isect) const { // Transform _Ray_ to object space Vector3f oErr, dErr; Ray ray = (*WorldToObject)(r, &oErr, &dErr); // Compute plane intersection for disk // Reject disk intersections for rays parallel to the disk's plane if (ray.d.z == 0) return false; Float tShapeHit = (height - ray.o.z) / ray.d.z; if (tShapeHit <= 0 || tShapeHit >= ray.tMax) return false; // See if hit point is inside disk radii and $\phimax$ Point3f pHit = ray(tShapeHit); Float dist2 = pHit.x * pHit.x + pHit.y * pHit.y; if (dist2 > radius * radius || dist2 < innerRadius * innerRadius) return false; // Refine disk intersection point pHit.z = height; // Test disk $\phi$ value against $\phimax$ Float phi = std::atan2(pHit.y, pHit.x); if (phi < 0) phi += 2 * Pi; if (phi > phiMax) return false; // Find parametric representation of disk hit Float u = phi / phiMax; Float rHit = std::sqrt(dist2); Float oneMinusV = ((rHit - innerRadius) / (radius - innerRadius)); Float v = 1 - oneMinusV; Vector3f dpdu(-phiMax * pHit.y, phiMax * pHit.x, 0.); Vector3f dpdv = Vector3f(pHit.x, pHit.y, 0.) * (innerRadius - radius) / rHit; Normal3f dndu(0, 0, 0), dndv(0, 0, 0); // Compute error bounds for disk intersection Vector3f pError(0., 0., 0.); // Initialize _SurfaceInteraction_ from parametric information *isect = (*ObjectToWorld)(SurfaceInteraction(pHit, pError, Point2f(u, v), -ray.d, dpdu, dpdv, dndu, dndv, ray.time, this)); // Update _tHit_ for quadric intersection *tHit = (Float)tShapeHit; return true; }
Real SaintVenantSetWaterVelocity::computeQpOffDiagJacobian(unsigned jvar) { RealVectorValue hU(_h[_qp]*_u_bc, 0., 0.); Real dpdu(0.0); if (jvar == _h_var) { switch (_equ_type) { case x_mom: dpdu = _eos.dp_dh(_h[_qp], hU); return _phi[_j][_qp]*dpdu*_normals[_qp](0)*_test[_i][_qp]; break; default: mooseError("'" << this->name() << "' Invalid equation name."); } } else return 0.; }
Vec3 PointLight::sampleDir() { //Amostrar ponto no globo Vec3 tempDir = UniformSampleHemisphere(drand48(), drand48()); float px, py; ConcentricSampleDisk(drand48(), drand48(), &px, &py); float prob = drand48(); Vec3 nn; if(prob < 0.5f) nn = Vec3(0.0, 1.0, 0.0); else nn = Vec3(0.0, -1.0, 0.0); Vec3 dpdu(-py, px, 0.f); Vec3 sn = normalize(dpdu); Vec3 tn = cross(nn, sn); //Local to world return Vec3(sn.x*tempDir.x + tn.x*tempDir.y + nn.x*tempDir.z, sn.y*tempDir.x + tn.y*tempDir.y + nn.y*tempDir.z, sn.z*tempDir.x + tn.z*tempDir.y + nn.z*tempDir.z); }
bool Cylinder::Intersect(const Ray &r, Float *tHit, SurfaceInteraction *isect, bool testAlphaTexture) const { Float phi; Point3f pHit; // Transform _Ray_ to object space Vector3f oErr, dErr; Ray ray = (*WorldToObject)(r, &oErr, &dErr); // Compute quadratic cylinder coefficients // Initialize _EFloat_ ray coordinate values EFloat ox(ray.o.x, oErr.x), oy(ray.o.y, oErr.y), oz(ray.o.z, oErr.z); EFloat dx(ray.d.x, dErr.x), dy(ray.d.y, dErr.y), dz(ray.d.z, dErr.z); EFloat a = dx * dx + dy * dy; EFloat b = 2 * (dx * ox + dy * oy); EFloat c = ox * ox + oy * oy - EFloat(radius) * EFloat(radius); // Solve quadratic equation for _t_ values EFloat t0, t1; if (!Quadratic(a, b, c, &t0, &t1)) return false; // Check quadric shape _t0_ and _t1_ for nearest intersection if (t0.UpperBound() > ray.tMax || t1.LowerBound() <= 0) return false; EFloat tShapeHit = t0; if (tShapeHit.LowerBound() <= 0) { tShapeHit = t1; if (tShapeHit.UpperBound() > ray.tMax) return false; } // Compute cylinder hit point and $\phi$ pHit = ray((Float)tShapeHit); // Refine cylinder intersection point Float hitRad = std::sqrt(pHit.x * pHit.x + pHit.y * pHit.y); pHit.x *= radius / hitRad; pHit.y *= radius / hitRad; phi = std::atan2(pHit.y, pHit.x); if (phi < 0) phi += 2 * Pi; // Test cylinder intersection against clipping parameters if (pHit.z < zMin || pHit.z > zMax || phi > phiMax) { if (tShapeHit == t1) return false; tShapeHit = t1; if (t1.UpperBound() > ray.tMax) return false; // Compute cylinder hit point and $\phi$ pHit = ray((Float)tShapeHit); // Refine cylinder intersection point Float hitRad = std::sqrt(pHit.x * pHit.x + pHit.y * pHit.y); pHit.x *= radius / hitRad; pHit.y *= radius / hitRad; phi = std::atan2(pHit.y, pHit.x); if (phi < 0) phi += 2 * Pi; if (pHit.z < zMin || pHit.z > zMax || phi > phiMax) return false; } // Find parametric representation of cylinder hit Float u = phi / phiMax; Float v = (pHit.z - zMin) / (zMax - zMin); // Compute cylinder $\dpdu$ and $\dpdv$ Vector3f dpdu(-phiMax * pHit.y, phiMax * pHit.x, 0); Vector3f dpdv(0, 0, zMax - zMin); // Compute cylinder $\dndu$ and $\dndv$ Vector3f d2Pduu = -phiMax * phiMax * Vector3f(pHit.x, pHit.y, 0); Vector3f d2Pduv(0, 0, 0), d2Pdvv(0, 0, 0); // Compute coefficients for fundamental forms Float E = Dot(dpdu, dpdu); Float F = Dot(dpdu, dpdv); Float G = Dot(dpdv, dpdv); Vector3f N = Normalize(Cross(dpdu, dpdv)); Float e = Dot(N, d2Pduu); Float f = Dot(N, d2Pduv); Float g = Dot(N, d2Pdvv); // Compute $\dndu$ and $\dndv$ from fundamental form coefficients Float invEGF2 = 1 / (E * G - F * F); Normal3f dndu = Normal3f((f * F - e * G) * invEGF2 * dpdu + (e * F - f * E) * invEGF2 * dpdv); Normal3f dndv = Normal3f((g * F - f * G) * invEGF2 * dpdu + (f * F - g * E) * invEGF2 * dpdv); // Compute error bounds for cylinder intersection Vector3f pError = gamma(3) * Abs(Vector3f(pHit.x, pHit.y, 0)); // Initialize _SurfaceInteraction_ from parametric information *isect = (*ObjectToWorld)(SurfaceInteraction(pHit, pError, Point2f(u, v), -ray.d, dpdu, dpdv, dndu, dndv, ray.time, this)); // Update _tHit_ for quadric intersection *tHit = (Float)tShapeHit; return true; }
bool Hyperboloid::Intersect(const Ray &r, Float *tHit, SurfaceInteraction *isect) const { Float phi, v; Point3f pHit; // Transform _Ray_ to object space Vector3f oErr, dErr; Ray ray = (*WorldToObject)(r, &oErr, &dErr); // Compute quadratic hyperboloid coefficients // Initialize _EFloat_ ray coordinate values EFloat ox(ray.o.x, oErr.x), oy(ray.o.y, oErr.y), oz(ray.o.z, oErr.z); EFloat dx(ray.d.x, dErr.x), dy(ray.d.y, dErr.y), dz(ray.d.z, dErr.z); EFloat a = ah * dx * dx + ah * dy * dy - ch * dz * dz; EFloat b = 2.f * (ah * dx * ox + ah * dy * oy - ch * dz * oz); EFloat c = ah * ox * ox + ah * oy * oy - ch * oz * oz - 1.f; // Solve quadratic equation for _t_ values EFloat t0, t1; if (!Quadratic(a, b, c, &t0, &t1)) return false; // Check quadric shape _t0_ and _t1_ for nearest intersection if (t0.UpperBound() > ray.tMax || t1.LowerBound() <= 0) return false; EFloat tShapeHit = t0; if (t0.LowerBound() <= 0) { tShapeHit = t1; if (tShapeHit.UpperBound() > ray.tMax) return false; } // Compute hyperboloid inverse mapping pHit = ray((Float)tShapeHit); v = (pHit.z - p1.z) / (p2.z - p1.z); Point3f pr = (1 - v) * p1 + v * p2; phi = std::atan2(pr.x * pHit.y - pHit.x * pr.y, pHit.x * pr.x + pHit.y * pr.y); if (phi < 0) phi += 2 * Pi; // Test hyperboloid intersection against clipping parameters if (pHit.z < zMin || pHit.z > zMax || phi > phiMax) { if (tShapeHit == t1) return false; tShapeHit = t1; if (t1.UpperBound() > ray.tMax) return false; // Compute hyperboloid inverse mapping pHit = ray((Float)tShapeHit); v = (pHit.z - p1.z) / (p2.z - p1.z); Point3f pr = (1 - v) * p1 + v * p2; phi = std::atan2(pr.x * pHit.y - pHit.x * pr.y, pHit.x * pr.x + pHit.y * pr.y); if (phi < 0) phi += 2 * Pi; if (pHit.z < zMin || pHit.z > zMax || phi > phiMax) return false; } // Compute parametric representation of hyperboloid hit Float u = phi / phiMax; // Compute hyperboloid $\dpdu$ and $\dpdv$ Float cosPhi = std::cos(phi), sinPhi = std::sin(phi); Vector3f dpdu(-phiMax * pHit.y, phiMax * pHit.x, 0.); Vector3f dpdv((p2.x - p1.x) * cosPhi - (p2.y - p1.y) * sinPhi, (p2.x - p1.x) * sinPhi + (p2.y - p1.y) * cosPhi, p2.z - p1.z); // Compute hyperboloid $\dndu$ and $\dndv$ Vector3f d2Pduu = -phiMax * phiMax * Vector3f(pHit.x, pHit.y, 0); Vector3f d2Pduv = phiMax * Vector3f(-dpdv.y, dpdv.x, 0.); Vector3f d2Pdvv(0, 0, 0); // Compute coefficients for fundamental forms Float E = Dot(dpdu, dpdu); Float F = Dot(dpdu, dpdv); Float G = Dot(dpdv, dpdv); Vector3f N = Normalize(Cross(dpdu, dpdv)); Float e = Dot(N, d2Pduu); Float f = Dot(N, d2Pduv); Float g = Dot(N, d2Pdvv); // Compute $\dndu$ and $\dndv$ from fundamental form coefficients Float invEGF2 = 1 / (E * G - F * F); Normal3f dndu = Normal3f((f * F - e * G) * invEGF2 * dpdu + (e * F - f * E) * invEGF2 * dpdv); Normal3f dndv = Normal3f((g * F - f * G) * invEGF2 * dpdu + (f * F - g * E) * invEGF2 * dpdv); // Compute error bounds for hyperboloid intersection // Compute error bounds for intersection computed with ray equation EFloat px = ox + tShapeHit * dx; EFloat py = oy + tShapeHit * dy; EFloat pz = oz + tShapeHit * dz; Vector3f pError = Vector3f(px.GetAbsoluteError(), py.GetAbsoluteError(), pz.GetAbsoluteError()); // Initialize _SurfaceInteraction_ from parametric information *isect = (*ObjectToWorld)(SurfaceInteraction(pHit, pError, Point2f(u, v), -ray.d, dpdu, dpdv, dndu, dndv, ray.time, this)); *tHit = (Float)tShapeHit; return true; }
// 1. -- intersection or not. // 2. -- fill differentialGeometry bool Sphere::Intersect(const Ray &r, float *tHit, float *rayEpsilon, DifferentialGeometry *dg) const { float phi; Point phit; // Transform _Ray_ to object space Ray ray; (*WorldToObject)(r, &ray); // 1. -- intersection or not. // Compute quadratic sphere coefficients float A = ray.d.x*ray.d.x + ray.d.y*ray.d.y + ray.d.z*ray.d.z; float B = 2 * (ray.d.x*ray.o.x + ray.d.y*ray.o.y + ray.d.z*ray.o.z); float C = ray.o.x*ray.o.x + ray.o.y*ray.o.y + ray.o.z*ray.o.z - radius*radius; // Solve quadratic equation for _t_ values float t0, t1; if (!Quadratic(A, B, C, &t0, &t1)) // in pbrt.h: Find quadratic discriminant return false; // Compute intersection distance along ray if (t0 > ray.maxt || t1 < ray.mint) return false; float thit = t0; if (t0 < ray.mint) { thit = t1; if (thit > ray.maxt) return false; } // Compute sphere hit position and $\phi$ phit = ray(thit); if (phit.x == 0.f && phit.y == 0.f) phit.x = 1e-5f * radius; phi = atan2f(phit.y, phit.x); if (phi < 0.) phi += 2.f*M_PI; // Test sphere intersection against clipping parameters if ((zmin > -radius && phit.z < zmin) || (zmax < radius && phit.z > zmax) || phi > phiMax) { if (thit == t1) return false; if (t1 > ray.maxt) return false; thit = t1; // Compute sphere hit position and $\phi$ phit = ray(thit); if (phit.x == 0.f && phit.y == 0.f) phit.x = 1e-5f * radius; phi = atan2f(phit.y, phit.x); if (phi < 0.) phi += 2.f*M_PI; if ((zmin > -radius && phit.z < zmin) || (zmax < radius && phit.z > zmax) || phi > phiMax) return false; } // 2. -- fill differentialGeometry // Find parametric representation of sphere hit float u = phi / phiMax; float theta = acosf(Clamp(phit.z / radius, -1.f, 1.f)); float v = (theta - thetaMin) / (thetaMax - thetaMin); // Compute sphere $\dpdu$ and $\dpdv$ float zradius = sqrtf(phit.x*phit.x + phit.y*phit.y); float invzradius = 1.f / zradius; float cosphi = phit.x * invzradius; float sinphi = phit.y * invzradius; Vector dpdu(-phiMax * phit.y, phiMax * phit.x, 0); Vector dpdv = (thetaMax-thetaMin) * Vector(phit.z * cosphi, phit.z * sinphi, -radius * sinf(theta)); // Compute sphere $\dndu$ and $\dndv$ Vector d2Pduu = -phiMax * phiMax * Vector(phit.x, phit.y, 0); Vector d2Pduv = (thetaMax - thetaMin) * phit.z * phiMax * Vector(-sinphi, cosphi, 0.); Vector d2Pdvv = -(thetaMax - thetaMin) * (thetaMax - thetaMin) * Vector(phit.x, phit.y, phit.z); // Compute coefficients for fundamental forms float E = Dot(dpdu, dpdu); float F = Dot(dpdu, dpdv); float G = Dot(dpdv, dpdv); Vector N = Normalize(Cross(dpdu, dpdv)); float e = Dot(N, d2Pduu); float f = Dot(N, d2Pduv); float g = Dot(N, d2Pdvv); // Compute $\dndu$ and $\dndv$ from fundamental form coefficients float invEGF2 = 1.f / (E*G - F*F); Normal dndu = Normal((f*F - e*G) * invEGF2 * dpdu + (e*F - f*E) * invEGF2 * dpdv); Normal dndv = Normal((g*F - f*G) * invEGF2 * dpdu + (f*F - g*E) * invEGF2 * dpdv); // Initialize _DifferentialGeometry_ from parametric information const Transform &o2w = *ObjectToWorld; *dg = DifferentialGeometry(o2w(phit), o2w(dpdu), o2w(dpdv), o2w(dndu), o2w(dndv), u, v, this); // Update _tHit_ for quadric intersection *tHit = thit; // Compute _rayEpsilon_ for quadric intersection *rayEpsilon = 5e-4f * *tHit; return true; }
bool Cone::Intersect(const Ray &r, float *tHit, float *rayEpsilon, DifferentialGeometry *dg) const { float phi; pbrt::Point phit; // Transform _Ray_ to object space Ray ray; (*WorldToObject)(r, &ray); // Compute quadratic cone coefficients float k = radius / height; k = k*k; float A = ray.d.x * ray.d.x + ray.d.y * ray.d.y - k * ray.d.z * ray.d.z; float B = 2 * (ray.d.x * ray.o.x + ray.d.y * ray.o.y - k * ray.d.z * (ray.o.z-height) ); float C = ray.o.x * ray.o.x + ray.o.y * ray.o.y - k * (ray.o.z -height) * (ray.o.z-height); // Solve quadratic equation for _t_ values float t0, t1; if (!Quadratic(A, B, C, &t0, &t1)) return false; // Compute intersection distance along ray if (t0 > ray.maxt || t1 < ray.mint) return false; float thit = t0; if (t0 < ray.mint) { thit = t1; if (thit > ray.maxt) return false; } // Compute cone inverse mapping phit = ray(thit); phi = atan2f(phit.y, phit.x); if (phi < 0.) phi += 2.f*M_PI; // Test cone intersection against clipping parameters if (phit.z < 0 || phit.z > height || phi > phiMax) { if (thit == t1) return false; thit = t1; if (t1 > ray.maxt) return false; // Compute cone inverse mapping phit = ray(thit); phi = atan2f(phit.y, phit.x); if (phi < 0.) phi += 2.f*M_PI; if (phit.z < 0 || phit.z > height || phi > phiMax) return false; } // Find parametric representation of cone hit float u = phi / phiMax; float v = phit.z / height; // Compute cone $\dpdu$ and $\dpdv$ Vector dpdu(-phiMax * phit.y, phiMax * phit.x, 0); Vector dpdv(-phit.x / (1.f - v), -phit.y / (1.f - v), height); // Compute cone $\dndu$ and $\dndv$ Vector d2Pduu = -phiMax * phiMax * Vector(phit.x, phit.y, 0.); Vector d2Pduv = phiMax / (1.f - v) * Vector(phit.y, -phit.x, 0.); Vector d2Pdvv(0, 0, 0); // Compute coefficients for fundamental forms float E = Dot(dpdu, dpdu); float F = Dot(dpdu, dpdv); float G = Dot(dpdv, dpdv); Vector N = Normalize(Cross(dpdu, dpdv)); float e = Dot(N, d2Pduu); float f = Dot(N, d2Pduv); float g = Dot(N, d2Pdvv); // Compute $\dndu$ and $\dndv$ from fundamental form coefficients float invEGF2 = 1.f / (E*G - F*F); Normal dndu = Normal((f*F - e*G) * invEGF2 * dpdu + (e*F - f*E) * invEGF2 * dpdv); Normal dndv = Normal((g*F - f*G) * invEGF2 * dpdu + (f*F - g*E) * invEGF2 * dpdv); // Initialize _DifferentialGeometry_ from parametric information const Transform &o2w = *ObjectToWorld; *dg = DifferentialGeometry(o2w(phit), o2w(dpdu), o2w(dpdv), o2w(dndu), o2w(dndv), u, v, this); // Update _tHit_ for quadric intersection *tHit = thit; // Compute _rayEpsilon_ for quadric intersection *rayEpsilon = 5e-4f * *tHit; return true; }
bool Hyperboloid::Intersect(const Ray &r, float *tHit, float *rayEpsilon, DifferentialGeometry *dg) const { float phi, v; Point phit; // Transform _Ray_ to object space Ray ray; (*WorldToObject)(r, &ray); // Compute quadratic hyperboloid coefficients float A = a*ray.d.x*ray.d.x + a*ray.d.y*ray.d.y - c*ray.d.z*ray.d.z; float B = 2.f * (a*ray.d.x*ray.o.x + a*ray.d.y*ray.o.y - c*ray.d.z*ray.o.z); float C = a*ray.o.x*ray.o.x + a*ray.o.y*ray.o.y - c*ray.o.z*ray.o.z - 1; // Solve quadratic equation for _t_ values float t0, t1; if (!Quadratic(A, B, C, &t0, &t1)) return false; // Compute intersection distance along ray if (t0 > ray.maxt || t1 < ray.mint) return false; float thit = t0; if (t0 < ray.mint) { thit = t1; if (thit > ray.maxt) return false; } // Compute hyperboloid inverse mapping phit = ray(thit); v = (phit.z - p1.z)/(p2.z - p1.z); Point pr = (1.f-v) * p1 + v * p2; phi = atan2f(pr.x*phit.y - phit.x*pr.y, phit.x*pr.x + phit.y*pr.y); if (phi < 0) phi += 2*M_PI; // Test hyperboloid intersection against clipping parameters if (phit.z < zmin || phit.z > zmax || phi > phiMax) { if (thit == t1) return false; thit = t1; if (t1 > ray.maxt) return false; // Compute hyperboloid inverse mapping phit = ray(thit); v = (phit.z - p1.z)/(p2.z - p1.z); Point pr = (1.f-v) * p1 + v * p2; phi = atan2f(pr.x*phit.y - phit.x*pr.y, phit.x*pr.x + phit.y*pr.y); if (phi < 0) phi += 2*M_PI; if (phit.z < zmin || phit.z > zmax || phi > phiMax) return false; } // Compute parametric representation of hyperboloid hit float u = phi / phiMax; // Compute hyperboloid $\dpdu$ and $\dpdv$ float cosphi = cosf(phi), sinphi = sinf(phi); Vector dpdu(-phiMax * phit.y, phiMax * phit.x, 0.); Vector dpdv((p2.x-p1.x) * cosphi - (p2.y-p1.y) * sinphi, (p2.x-p1.x) * sinphi + (p2.y-p1.y) * cosphi, p2.z-p1.z); // Compute hyperboloid $\dndu$ and $\dndv$ Vector d2Pduu = -phiMax * phiMax * Vector(phit.x, phit.y, 0); Vector d2Pduv = phiMax * Vector(-dpdv.y, dpdv.x, 0.); Vector d2Pdvv(0, 0, 0); // Compute coefficients for fundamental forms float E = Dot(dpdu, dpdu); float F = Dot(dpdu, dpdv); float G = Dot(dpdv, dpdv); Vector N = Normalize(Cross(dpdu, dpdv)); float e = Dot(N, d2Pduu); float f = Dot(N, d2Pduv); float g = Dot(N, d2Pdvv); // Compute $\dndu$ and $\dndv$ from fundamental form coefficients float invEGF2 = 1.f / (E*G - F*F); Normal dndu = Normal((f*F - e*G) * invEGF2 * dpdu + (e*F - f*E) * invEGF2 * dpdv); Normal dndv = Normal((g*F - f*G) * invEGF2 * dpdu + (f*F - g*E) * invEGF2 * dpdv); // Initialize _DifferentialGeometry_ from parametric information const Transform &o2w = *ObjectToWorld; *dg = DifferentialGeometry(o2w(phit), o2w(dpdu), o2w(dpdv), o2w(dndu), o2w(dndv), u, v, this); // Update _tHit_ for quadric intersection *tHit = thit; // Compute _rayEpsilon_ for quadric intersection *rayEpsilon = 5e-4f * *tHit; return true; }
bool Rectangle::Intersect(const Ray &r, float *tHit, float *rayEpsilon, DifferentialGeometry *dg) const { // Transform _Ray_ to object space Ray ray; (*WorldToObject)(r, &ray); // Compute plane intersection for disk // Checks if the plane is parallel to the ray or not // We can get the direction of the ray // If the Z component of the direction of the ray is zero // then, the ray is parallel to the plane and in such case // there is no intersection point between the ray and the plane. if (fabsf(ray.d.z) < 1e-7) return false; // Now, the direction of the ray is not parallel to the plane // We have to check if the intersection happens or not // We have to compute the parametric t where the ray intersects the plane // We want to find t such that the z-component of the ray intersects the plane // The ray "line" equation is l = l0 + (l1 - l0) * t // l1 - l0 will give us the distance between the two points on the plane // Then t is the ratio and in such case it should be between 0 and 1 // Considering that the rectangle completely lies in the z plane /// distance = l1 - l0 /// thit = (l - l0) / distance // But since we assume that the plane is located at height // Then, the point l is at height on the plane /// l = height float thit = (height - ray.o.z) / ray.d.z; // Then we check if the thit is between the ratio of 0 and 1 that is mapped // between ray.mint and ray.maxt, if not retrun false if (thit < ray.mint || thit > ray.maxt) return false; // Then we see if the point lies inside the disk or not // Substitute the thit in the ray equation to get hit point on the ray Point phit = ray(thit); // We have to make sure that the interesction lies inside the plane if (!(phit.x < x/2 && phit.x > -x/2 && phit.y < y/2 && phit.y > -y/2)) return false; // Assuming that the plane is formed from the following 4 points // P0, P1, P2, P3 // // p0 *---------------* p1 // | | // | | // | | // | O | // | | // | | // | | // p2 *---------------* p3 -> X // // P0 @ (-x/2, y/2) // P1 @ (x/2, y/2) // P2 @ (-x/2, -y/2) // P3 @ (x/2, -y/2) Point P0(-x/2, y/2, height), P1(x/2, y/2, height); Point P2(-x/2, -y/2, height), P3(x/2, -y/2, height); /// Now, we have to find the parametric form of the plane in terms of (u,v) /// Plane equation can be formed by at least 3 points P0, P1, P2 /// P0 -> P1 (vector 1) /// P0 -> p2 (vector 2) /// An arbitrary point on the plane p is found in the following parametric form /// P = P0 + (P1 - P0) u + (P2 - P0) v /// Now we need to express two explicit equations of u and v /// So, we have to construct the system of equation that solves for u and v /// /// Since we have found the intersection point between the plane and the line /// we have to use it to formalize the system of equations that will be used /// to find the parametric form of the plane /// Plane equation is : P = P0 + (P1 - P0) u + (P2 - P0) v /// Ray equation is : l = l0 + (l1 - l0) * thit /// But l = P, then /// l0 + (l1 - l0) * thit = P0 + (P1 - P0) * u + (P2 - P0) * v /// l0 - P0 = (l0 - l1) * thit + (P1 - P0) * u + (P2 - P0) * v /// MAPPING : l0 = ray.o /// [l0.x - P0.x] = [l0.x - l1.x P1.x - P0.x P2.x - P0.x] [t] /// [l0.y - P0.y] = [l0.y - l1.y P1.y - P0.y P2.y - P0.y] [u] /// [l0.z - P0.z] = [l0.z - l1.z P1.z - P0.z P2.z - P0.z] [v] /// /// Then, we should find the inverse of the matrix in order to /// solve for u,v and t for check // System AX = B float a11 = ray.o.x - 0; float a12 = P1.x - P0.x; float a13 = P2.x - P0.x; float a21 = ray.o.y - 0; float a22 = P1.y - P0.y; float a23 = P2.y - P0.y; float a31 = ray.o.y - height; float a32 = P1.z - P0.z; float a33 = P2.z - P0.z; float b1 = -7; float b2 = -2; float b3 = 14; float x1 = 0; float x2 = 0; float x3 = 0; Imath::M33f A(a11,a12,a13,a21,a22,a23,a31,a32,a33), AInverted; Imath::V3f X(x1, x2, x3); Imath::V3f B(b1,b2, b3); // This operation has been checked and working for getting // the correct inverse of the matrix A AInverted = A.invert(false); x1 = AInverted[0][0] * B[0] + AInverted[0][1] * B[1] + AInverted[0][2] * B[2]; x2 = AInverted[1][0] * B[0] + AInverted[1][1] * B[1] + AInverted[1][2] * B[2]; x3 = AInverted[2][0] * B[0] + AInverted[2][1] * B[1] + AInverted[2][2] * B[2]; /// Then we have u = something, and v = something /// /// Then we come for the derivatives, so we have to find the derivatives /// from the parametric forms defined above for the plane equations /// dpdu = (P1 - P0) /// dpdv = (P2 - P0) /// /// For the normal we have the always fixed direction in y /// So the derivative for the normal is zero /// dndu = (0, 0, 0) dndv = (0, 0, 0) /// /// Then we can construct the DifferentilGeometry and go ahead // Find parametric representation of disk hit float u = x2; float v = x3; Vector dpdu(P1.x - P0.x, P1.y - P0.y, P1.z - P0.z); Vector dpdv(P2.x - P0.x, P2.y - P0.y, P2.z - P0.z); Normal dndu(0,0,0), dndv(0,0,0); // Initialize _DifferentialGeometry_ from parametric information const Transform &o2w = *ObjectToWorld; *dg = DifferentialGeometry(o2w(phit), o2w(dpdu), o2w(dpdv), o2w(dndu), o2w(dndv), u, v, this); // Update _tHit_ for quadric intersection *tHit = thit; // Compute _rayEpsilon_ for quadric intersection *rayEpsilon = 5e-4f * *tHit; return true; }
bool Sphere::intersect(const Ray &ray, float *t_hit, float *ray_epsilon, DifferentialGeometry *diff_geo) const { // Transform Ray to object space Ray w_ray; (*world_to_object)(ray, &w_ray); // Compute quadratic sphere coefficients float phi; Point phit; float A = w_ray.d.x * w_ray.d.x + w_ray.d.y * w_ray.d.y + w_ray.d.z * w_ray.d.z; float B = 2 * (w_ray.d.x * w_ray.o.x + w_ray.d.y * w_ray.o.y + w_ray.d.z * w_ray.o.z); float C = w_ray.o.x*w_ray.o.x + w_ray.o.y*w_ray.o.y + w_ray.o.z*w_ray.o.z - _radius*_radius; // Solve quadratic equation for t values float t0, t1; if (!quadratic(A, B, C, &t0, &t1)) return false; // Compute intersection distance along ray if (t0 > w_ray.maxt || t1 < w_ray.mint) return false; float thit = t0; if (t0 < w_ray.mint) { thit = t1; if (thit > w_ray.maxt) return false; } // Compute sphere hit position and phi phit = w_ray(thit); if (phit.x == 0.f && phit.y == 0.f) phit.x = 1e-5f * _radius; phi = atan2f(phit.y, phit.x); if (phi < 0.) phi += 2.f * M_PI; // Test sphere intersection against clipping parameters if ((_z_min > -_radius && phit.z < _z_min) || (_z_max < _radius && phit.z > _z_max) || phi > _phi_max) { // clip t0(t1) if (thit == t1) return false; if (t1 > w_ray.maxt) return false; thit = t1; // Compute sphere hit position and phi phit = w_ray(thit); if (phit.x == 0.f && phit.y == 0.f) phit.x = 1e-5f * _radius; phi = atan2f(phit.y, phit.x); if (phi < 0.) phi += 2.f * M_PI; if ((_z_min > -_radius && phit.z < _z_min) || (_z_max < _radius && phit.z > _z_max) || phi > _phi_max) // clip t1 return false; } // Find parametric representatio n of sphere hit float u = phi / _phi_max; float theta = acosf(clamp(phit.z / _radius, -1.f, 1.f)); float v = (theta - _theta_min) / (_theta_max - _theta_min); float z_radius = sqrtf(phit.x * phit.x + phit.y * phit.y); float inv_z_radius = 1.f / z_radius; float cos_phi = phit.x * inv_z_radius; float sin_phi = phit.y * inv_z_radius; Vec3 dpdu(-_phi_max * phit.y, _phi_max * phit.x, 0); Vec3 dpdv = (_theta_max - _theta_min) * Vec3(phit.z * cos_phi, phit.z * sin_phi, _radius * sinf(theta)); //auto d2Pduu = -_phi_max * _phi_max * Vec3(phit.x, phit.y, 0); //auto d2Pduv = (_theta_max - _theta_min) * phit.z * _phi_max * Vec3(-sin_phi, cos_phi, 0.f); //auto d2Pdvv = (_theta_max - _theta_min) * (_theta_max - _theta_min) * Vec3(phit.x, phit.y, phit.z); //Normal dndu, dndv; //calc_dndu_dndv(dpdu, dpdv, d2Pduu, d2Pduv, d2Pdvv, &dndu, &dndv); Normal dndu(dpdu); Normal dndv(dpdv); const auto &o2w = *object_to_world; *diff_geo = DifferentialGeometry(o2w(phit), o2w(dpdu), o2w(dpdv), o2w(dndu), o2w(dndv), u, v, this); *t_hit = thit; *ray_epsilon = 5e-4f * *t_hit; return true; }
bool Sphere::hit(const Ray &ws_ray, float &thit, std::shared_ptr<DifferentialGeometry> &dg) const { float phi; Point phit; //UNCOMMENT FOR BROKEN BB if(!mImpl->bb.hit(ws_ray)) return false; // Transform the ray into object space Transform transform = worldToObjectSpace(); Ray os_ray = transform(ws_ray); // Do ray-sphere intersection in object space // Compute quadratic sphere coefficients float A = os_ray.dir().x() * os_ray.dir().x() + os_ray.dir().y() * os_ray.dir().y() + os_ray.dir().z() * os_ray.dir().z(); float B = 2.0 * (os_ray.dir().x() * os_ray.origin().x() + os_ray.dir().y() * os_ray.origin().y() + os_ray.dir().z() * os_ray.origin().z()); float C = os_ray.origin().x() * os_ray.origin().x() + os_ray.origin().y() * os_ray.origin().y() + os_ray.origin().z() * os_ray.origin().z() - mImpl->radius * mImpl->radius; // Solve quadratic equation for t values float t0, t1; if (!mImpl->Quadratic(A,B,C, &t0, &t1)) return false; // compute intersection distance along ray if (t0 > os_ray.maxt() || t1 < os_ray.mint()) return false; thit = t0; if (t0 < os_ray.mint()) { thit = t1; if (thit > os_ray.maxt()) return false; } // Compute sphere hit position and phi phit = os_ray(thit); if (phit.x() == 0.f && phit.y() == 0.f) phit.x(1e-5f * mImpl->radius); phi = atan2f(phit.y(), phit.x()); if (phi < 0.) phi += 2.f*M_PI; // Test against clipping parameters if ((mImpl->zmin > -mImpl->radius && phit.z() < mImpl->zmin) || (mImpl->zmax < mImpl->radius && phit.z() > mImpl->zmax) || phi > mImpl->phiMax) { if (thit == t1) return false; thit = t1; if ((mImpl->zmin > -mImpl->radius && phit.z() < mImpl->zmin) || (mImpl->zmax < mImpl->radius && phit.z() > mImpl->zmax) || phi > mImpl->phiMax) return false; } // find parametric representation of sphere float u = phi/mImpl->phiMax; float theta = acosf(Clamp(phit.z()/mImpl->radius, -1.f, 1.f)); float v = (theta - mImpl->thetaMin) / (mImpl->thetaMax - mImpl->thetaMin); float zradius = sqrtf(phit.x() * phit.x() + phit.y() * phit.y()); float invzradius = 1.f / zradius; float cosphi = phit.x() * invzradius; float sinphi = phit.y() * invzradius; Vector dpdu(-mImpl->phiMax * phit.y(), mImpl->phiMax * phit.x(), 0); Vector dpdv = (mImpl->thetaMax - mImpl->thetaMin) * Vector(phit.z() * cosphi, phit.z() * sinphi, -mImpl->radius * sinf(theta)); Vector d2Pduu = -mImpl->phiMax * mImpl->phiMax * Vector(phit.x(), phit.y(), 0.0f); Vector d2Pduv = (mImpl->thetaMax - mImpl->thetaMin) * phit.z() * mImpl->phiMax * Vector(-sinphi, cosphi, 0.0f); Vector d2Pdvv = -(mImpl->thetaMax - mImpl->thetaMin) * (mImpl->thetaMax - mImpl->thetaMin) * Vector(phit.x(), phit.y(), phit.z()); float E = dpdu.dot(dpdu); float F = dpdu.dot(dpdv); float G = dpdv.dot(dpdv); Vector N = dpdu.cross(dpdv).normalized(); float e = N.dot(d2Pduu); float f = N.dot(d2Pduv); float g = N.dot(d2Pdvv); float invEGF2 = 1.f/(E * G - F * F); Normal dndu = Normal((f * F - e * G) * invEGF2 * dpdu + (e * F - f * E) * invEGF2 * dpdv); Normal dndv = Normal((g * F - f * G) * invEGF2 * dpdu + (f*F - g * E) * invEGF2 * dpdv); // if the ray intersects the sphere return true std::shared_ptr<DifferentialGeometry> dg_temp(new DifferentialGeometry(mImpl->o2w(os_ray(thit)), mImpl->o2w(dpdu), mImpl->o2w(dpdv), mImpl->o2w(dndu), mImpl->o2w(dndv), u, v, this)); dg_temp->dir = ws_ray.dir(); dg = dg_temp; return true; }
NormalVector ShapeParabolicRectangle::GetNormal( double u, double v ) const { Vector3D dpdu( widthX.getValue(), ( (-0.5 + u) * widthX.getValue() * widthX.getValue() )/(2 * focusLength.getValue()), 0 ); Vector3D dpdv( 0.0, (( -0.5 + v) * widthZ.getValue() * widthZ.getValue() ) /( 2 * focusLength.getValue() ), widthZ.getValue() ); return Normalize( NormalVector( CrossProduct( dpdu, dpdv ) ) ); }
bool ShapeParabolicRectangle::Intersect(const Ray& objectRay, double *tHit, DifferentialGeometry *dg) const { double focus = focusLength.getValue(); double wX = widthX.getValue(); double wZ = widthZ.getValue(); // Compute quadratic coefficients double A = objectRay.direction().x * objectRay.direction().x + objectRay.direction().z * objectRay.direction().z; double B = 2.0 * ( objectRay.direction().x * objectRay.origin.x + objectRay.direction().z * objectRay.origin.z - 2 * focus * objectRay.direction().y ); double C = objectRay.origin.x * objectRay.origin.x + objectRay.origin.z * objectRay.origin.z - 4 * focus * objectRay.origin.y; // Solve quadratic equation for _t_ values double t0, t1; if( !gf::Quadratic( A, B, C, &t0, &t1 ) ) return false; // Compute intersection distance along ray if( t0 > objectRay.maxt || t1 < objectRay.mint ) return false; double thit = ( t0 > objectRay.mint )? t0 : t1 ; if( thit > objectRay.maxt ) return false; //Evaluate Tolerance double tol = 0.00001; //Compute possible hit position Point3D hitPoint = objectRay( thit ); // Test intersection against clipping parameters if( (thit - objectRay.mint) < tol || hitPoint.x < ( - wX / 2 ) || hitPoint.x > ( wX / 2 ) || hitPoint.z < ( - wZ / 2 ) || hitPoint.z > ( wZ / 2 ) ) { if ( thit == t1 ) return false; if ( t1 > objectRay.maxt ) return false; thit = t1; hitPoint = objectRay( thit ); if( (thit - objectRay.mint) < tol || hitPoint.x < ( - wX / 2 ) || hitPoint.x > ( wX / 2 ) || hitPoint.z < ( - wZ / 2 ) || hitPoint.z > ( wZ / 2 ) ) return false; } // Now check if the function is being called from IntersectP, // in which case the pointers tHit and dg are 0 if( ( tHit == 0 ) && ( dg == 0 ) ) return true; else if( ( tHit == 0 ) || ( dg == 0 ) ) gf::SevereError( "Function ParabolicCyl::Intersect(...) called with null pointers" ); /////////////////////////////////////////////////////////////////////////////////////// // Compute possible parabola hit position // Find parametric representation of paraboloid hit double u = ( hitPoint.x / wX ) + 0.5; double v = ( hitPoint.z / wZ ) + 0.5; Vector3D dpdu( wX, ( (-0.5 + u) * wX * wX ) / ( 2 * focus ), 0 ); Vector3D dpdv( 0.0, (( -0.5 + v) * wZ * wZ ) /( 2 * focus ), wZ ); // Compute parabaloid \dndu and \dndv Vector3D d2Pduu( 0.0, (wX * wX ) /( 2 * focus ), 0.0 ); Vector3D d2Pduv( 0.0, 0.0, 0.0 ); Vector3D d2Pdvv( 0.0, (wZ * wZ ) /( 2 * focus ), 0.0 ); // Compute coefficients for fundamental forms double E = DotProduct(dpdu, dpdu); double F = DotProduct(dpdu, dpdv); double G = DotProduct(dpdv, dpdv); NormalVector N = Normalize( NormalVector( CrossProduct( dpdu, dpdv ) ) ); double e = DotProduct(N, d2Pduu); double f = DotProduct(N, d2Pduv); double g = DotProduct(N, d2Pdvv); // Compute \dndu and \dndv from fundamental form coefficients double invEGF2 = 1.0 / (E*G - F*F); Vector3D dndu = (f*F - e*G) * invEGF2 * dpdu + (e*F - f*E) * invEGF2 * dpdv; Vector3D dndv = (g*F - f*G) * invEGF2 * dpdu + (f*F - g*E) * invEGF2 * dpdv; // Initialize _DifferentialGeometry_ from parametric information *dg = DifferentialGeometry(hitPoint, dpdu, dpdv, dndu, dndv, u, v, this); dg->shapeFrontSide = ( DotProduct( N, objectRay.direction() ) > 0 ) ? false : true; /////////////////////////////////////////////////////////////////////////////////////// // Update _tHit_ for quadric intersection *tHit = thit; return true; }
bool Paraboloid::Intersect(const Ray &r, Float *tHit, SurfaceInteraction *isect) const { Float phi; Point3f pHit; // Transform _Ray_ to object space Vector3f oErr, dErr; Ray ray = (*WorldToObject)(r, &oErr, &dErr); // Compute quadratic paraboloid coefficients // Initialize _EFloat_ ray coordinate values EFloat ox(ray.o.x, oErr.x), oy(ray.o.y, oErr.y), oz(ray.o.z, oErr.z); EFloat dx(ray.d.x, dErr.x), dy(ray.d.y, dErr.y), dz(ray.d.z, dErr.z); EFloat k = EFloat(zMax) / (EFloat(radius) * EFloat(radius)); EFloat a = k * (dx * dx + dy * dy); EFloat b = 2.f * k * (dx * ox + dy * oy) - dz; EFloat c = k * (ox * ox + oy * oy) - oz; // Solve quadratic equation for _t_ values EFloat t0, t1; if (!Quadratic(a, b, c, &t0, &t1)) return false; // Check quadric shape _t0_ and _t1_ for nearest intersection if (t0.UpperBound() > ray.tMax || t1.LowerBound() <= 0) return false; EFloat tShapeHit = t0; if (tShapeHit.LowerBound() <= 0) { tShapeHit = t1; if (tShapeHit.UpperBound() > ray.tMax) return false; } // Compute paraboloid inverse mapping pHit = ray((Float)tShapeHit); phi = std::atan2(pHit.y, pHit.x); if (phi < 0.) phi += 2 * Pi; // Test paraboloid intersection against clipping parameters if (pHit.z < zMin || pHit.z > zMax || phi > phiMax) { if (tShapeHit == t1) return false; tShapeHit = t1; if (t1.UpperBound() > ray.tMax) return false; // Compute paraboloid inverse mapping pHit = ray((Float)tShapeHit); phi = std::atan2(pHit.y, pHit.x); if (phi < 0.) phi += 2 * Pi; if (pHit.z < zMin || pHit.z > zMax || phi > phiMax) return false; } // Find parametric representation of paraboloid hit Float u = phi / phiMax; Float v = (pHit.z - zMin) / (zMax - zMin); // Compute paraboloid $\dpdu$ and $\dpdv$ Vector3f dpdu(-phiMax * pHit.y, phiMax * pHit.x, 0.); Vector3f dpdv = (zMax - zMin) * Vector3f(pHit.x / (2 * pHit.z), pHit.y / (2 * pHit.z), 1.); // Compute paraboloid $\dndu$ and $\dndv$ Vector3f d2Pduu = -phiMax * phiMax * Vector3f(pHit.x, pHit.y, 0); Vector3f d2Pduv = (zMax - zMin) * phiMax * Vector3f(-pHit.y / (2 * pHit.z), pHit.x / (2 * pHit.z), 0); Vector3f d2Pdvv = -(zMax - zMin) * (zMax - zMin) * Vector3f(pHit.x / (4 * pHit.z * pHit.z), pHit.y / (4 * pHit.z * pHit.z), 0.); // Compute coefficients for fundamental forms Float E = Dot(dpdu, dpdu); Float F = Dot(dpdu, dpdv); Float G = Dot(dpdv, dpdv); Vector3f N = Normalize(Cross(dpdu, dpdv)); Float e = Dot(N, d2Pduu); Float f = Dot(N, d2Pduv); Float g = Dot(N, d2Pdvv); // Compute $\dndu$ and $\dndv$ from fundamental form coefficients Float invEGF2 = 1 / (E * G - F * F); Normal3f dndu = Normal3f((f * F - e * G) * invEGF2 * dpdu + (e * F - f * E) * invEGF2 * dpdv); Normal3f dndv = Normal3f((g * F - f * G) * invEGF2 * dpdu + (f * F - g * E) * invEGF2 * dpdv); // Compute error bounds for paraboloid intersection // Compute error bounds for intersection computed with ray equation EFloat px = ox + tShapeHit * dx; EFloat py = oy + tShapeHit * dy; EFloat pz = oz + tShapeHit * dz; Vector3f pError = Vector3f(px.GetAbsoluteError(), py.GetAbsoluteError(), pz.GetAbsoluteError()); // Initialize _SurfaceInteraction_ from parametric information *isect = (*ObjectToWorld)(SurfaceInteraction(pHit, pError, Point2f(u, v), -ray.d, dpdu, dpdv, dndu, dndv, ray.time, this)); *tHit = (Float)tShapeHit; return true; }
bool Sphere::Intersect(const Ray &r, Float *tHit, SurfaceInteraction *isect, bool testAlphaTexture) const { Float phi; Point3f pHit; // Transform _Ray_ to object space Vector3f oErr, dErr; Ray ray = (*WorldToObject)(r, &oErr, &dErr); // Compute quadratic sphere coefficients // Initialize _EFloat_ ray coordinate values EFloat ox(ray.o.x, oErr.x), oy(ray.o.y, oErr.y), oz(ray.o.z, oErr.z); EFloat dx(ray.d.x, dErr.x), dy(ray.d.y, dErr.y), dz(ray.d.z, dErr.z); EFloat a = dx * dx + dy * dy + dz * dz; EFloat b = 2 * (dx * ox + dy * oy + dz * oz); EFloat c = ox * ox + oy * oy + oz * oz - EFloat(radius) * EFloat(radius); // Solve quadratic equation for _t_ values EFloat t0, t1; if (!Quadratic(a, b, c, &t0, &t1)) return false; // Check quadric shape _t0_ and _t1_ for nearest intersection if (t0.UpperBound() > ray.tMax || t1.LowerBound() <= 0) return false; EFloat tShapeHit = t0; if (tShapeHit.LowerBound() <= 0) { tShapeHit = t1; if (tShapeHit.UpperBound() > ray.tMax) return false; } // Compute sphere hit position and $\phi$ pHit = ray((Float)tShapeHit); // Refine sphere intersection point pHit *= radius / Distance(pHit, Point3f(0, 0, 0)); if (pHit.x == 0 && pHit.y == 0) pHit.x = 1e-5f * radius; phi = std::atan2(pHit.y, pHit.x); if (phi < 0) phi += 2 * Pi; // Test sphere intersection against clipping parameters if ((zMin > -radius && pHit.z < zMin) || (zMax < radius && pHit.z > zMax) || phi > phiMax) { if (tShapeHit == t1) return false; if (t1.UpperBound() > ray.tMax) return false; tShapeHit = t1; // Compute sphere hit position and $\phi$ pHit = ray((Float)tShapeHit); // Refine sphere intersection point pHit *= radius / Distance(pHit, Point3f(0, 0, 0)); if (pHit.x == 0 && pHit.y == 0) pHit.x = 1e-5f * radius; phi = std::atan2(pHit.y, pHit.x); if (phi < 0) phi += 2 * Pi; if ((zMin > -radius && pHit.z < zMin) || (zMax < radius && pHit.z > zMax) || phi > phiMax) return false; } // Find parametric representation of sphere hit Float u = phi / phiMax; Float theta = std::acos(Clamp(pHit.z / radius, -1, 1)); Float v = (theta - thetaMin) / (thetaMax - thetaMin); // Compute sphere $\dpdu$ and $\dpdv$ Float zRadius = std::sqrt(pHit.x * pHit.x + pHit.y * pHit.y); Float invZRadius = 1 / zRadius; Float cosPhi = pHit.x * invZRadius; Float sinPhi = pHit.y * invZRadius; Vector3f dpdu(-phiMax * pHit.y, phiMax * pHit.x, 0); Vector3f dpdv = (thetaMax - thetaMin) * Vector3f(pHit.z * cosPhi, pHit.z * sinPhi, -radius * std::sin(theta)); // Compute sphere $\dndu$ and $\dndv$ Vector3f d2Pduu = -phiMax * phiMax * Vector3f(pHit.x, pHit.y, 0); Vector3f d2Pduv = (thetaMax - thetaMin) * pHit.z * phiMax * Vector3f(-sinPhi, cosPhi, 0.); Vector3f d2Pdvv = -(thetaMax - thetaMin) * (thetaMax - thetaMin) * Vector3f(pHit.x, pHit.y, pHit.z); // Compute coefficients for fundamental forms Float E = Dot(dpdu, dpdu); Float F = Dot(dpdu, dpdv); Float G = Dot(dpdv, dpdv); Vector3f N = Normalize(Cross(dpdu, dpdv)); Float e = Dot(N, d2Pduu); Float f = Dot(N, d2Pduv); Float g = Dot(N, d2Pdvv); // Compute $\dndu$ and $\dndv$ from fundamental form coefficients Float invEGF2 = 1 / (E * G - F * F); Normal3f dndu = Normal3f((f * F - e * G) * invEGF2 * dpdu + (e * F - f * E) * invEGF2 * dpdv); Normal3f dndv = Normal3f((g * F - f * G) * invEGF2 * dpdu + (f * F - g * E) * invEGF2 * dpdv); // Compute error bounds for sphere intersection Vector3f pError = gamma(5) * Abs((Vector3f)pHit); // Initialize _SurfaceInteraction_ from parametric information *isect = (*ObjectToWorld)(SurfaceInteraction(pHit, pError, Point2f(u, v), -ray.d, dpdu, dpdv, dndu, dndv, ray.time, this)); // Update _tHit_ for quadric intersection *tHit = (Float)tShapeHit; return true; }
bool Sphere::Intersect(const Ray &r, Float *distance, Float *rayEpsilon, DifferentialGeometry *dg) const { Ray ray; (*worldToLocal)(r, &ray); // Compute quadratic sphere coefficients Float A = ray.d.x * ray.d.x + ray.d.y * ray.d.y + ray.d.z * ray.d.z; Float B = 2 * (ray.d.x * ray.o.x + ray.d.y * ray.o.y + ray.d.z * ray.o.z); Float C = ray.o.x * ray.o.x + ray.o.y * ray.o.y + ray.o.z * ray.o.z - mRad * mRad; Float t0, t1; if (!Quadratic(A, B, C, &t0, &t1)) return false; // Compute intersection distance along ray if (t0 > ray.maxT || t1 < ray.minT) return false; Float thit = t0; if (t0 < ray.minT) { thit = t1; if (thit > ray.maxT) return false; } //这里开始计算参数化变量 //计算phi Point phit; Float phi; phit = ray(thit); if (phit.x == 0.f && phit.y == 0.f) phit.x = 1e-5f * mRad; //排除除零的情况 phi = atan2f(phit.y, phit.x); if (phi < 0.) phi += 2.f * Pi; //保证phi在2PI之中 //判断是否在Z坐标之间的裁剪空间中 if ((mZMin > -mRad && phit.z < mZMin) || (mZMax < mRad && phit.z > mZMax) || phi > mPhiMax) { if (thit == t1) return false; if (t1 > ray.maxT) return false; thit = t1; phit = ray(thit); if (phit.x == 0.f && phit.y == 0.f) phit.x = 1e-5f * mRad; phi = atan2f(phit.y, phit.x); if (phi < 0.) phi += 2.f * Pi; if ((mZMin > -mRad && phit.z < mZMin) || (mZMax < mRad && phit.z > mZMax) || phi > mPhiMax) return false; } // Find parametric representation of sphere hit //寻找参数化的u和v Float u = phi / mPhiMax; Float theta = acosf(Clamp(phit.z / mRad, -1.f, 1.f)); Float v = (theta - mThetaMin) / (mThetaMax - mThetaMin); // 计算偏导 偏导还不是很熟悉,所以这里照搬了PBRT的公式,详细公式可以查阅PBRT Float zradius = sqrtf(phit.x * phit.x + phit.y * phit.y); Float invzradius = 1.f / zradius; Float cosphi = phit.x * invzradius; Float sinphi = phit.y * invzradius; Vector3f dpdu(-mPhiMax * phit.y, mPhiMax * phit.x, 0); Vector3f dpdv = (mThetaMax - mThetaMin) * Vector3f(phit.z * cosphi, phit.z * sinphi, -mRad * sinf(theta)); //计算法线的偏导 Vector3f d2Pduu = -mPhiMax * mPhiMax * Vector3f(phit.x, phit.y, 0); Vector3f d2Pduv = (mThetaMax - mThetaMin) * phit.z * mPhiMax * Vector3f(-sinphi, cosphi, 0.); Vector3f d2Pdvv = -(mThetaMax - mThetaMin) * (mThetaMax - mThetaMin) * Vector3f(phit.x, phit.y, phit.z); Float E = Dot(dpdu, dpdu); Float F = Dot(dpdu, dpdv); Float G = Dot(dpdv, dpdv); Vector3f N = Normalize(Cross(dpdu, dpdv)); Float e = Dot(N, d2Pduu); Float f = Dot(N, d2Pduv); Float g = Dot(N, d2Pdvv); Float invEGF2 = 1.f / (E * G - F * F); Normal dndu = Normal( (f * F - e * G) * invEGF2 * dpdu + (e * F - f * E) * invEGF2 * dpdv); Normal dndv = Normal( (g * F - f * G) * invEGF2 * dpdu + (f * F - g * E) * invEGF2 * dpdv); const Transform &o2w = *localToWorld; *dg = DifferentialGeometry(o2w(phit), o2w(dpdu), o2w(dpdv), o2w(dndu), o2w(dndv), u, v, this); *distance = thit; *rayEpsilon = 5e-4f * *distance; //交点处的Float误差 return true; }
bool Sphere::Intersect( Ray const &ray, float *tHit, float *epsilon, DifferentialGeometry *geom ) const { Transform tf = Tform(); Ray r = ray * Inverse( tf ); float t; if( !Intersect( ray, &t ) ) return false; // compute differential geometry Vec4 p = ray.Point( t ); float x = p.X(); float y = p.Y(); float z = p.Z(); if( x == 0.0f && z == 0.0f ) { // can't have both atan2 arguments be zero z = kEpsilon * m_radius; } float theta = atan2( p.X(), p.Z() ); if( theta < 0.0f ) { // remap theta to [0, 2pi] to match sphere's definition theta += k2Pi; } float phi = Acos( Clamp( z / m_radius, -1.0f, 1.0f ) ); // parameterize sphere hit float u = theta * kInv2Pi; float v = phi * kInvPi; float sTheta, cTheta; float sPhi, cPhi; SinCos( theta, &sTheta, &cTheta ); SinCos( phi, &sPhi, &cPhi ); Vec4 dpdu( k2Pi * z, 0.0f, -k2Pi * x, 0.0f ); Vec4 dpdv( kPi * y * sTheta, -kPi * m_radius * sPhi, kPi * y * cTheta, 0.0f ); Vec4 d2pdu2( -k2Pi * k2Pi * x, 0.0f, -k2Pi * k2Pi * z, 0.0f ); Vec4 d2pduv( k2Pi * kPi * y * cTheta, 0.0f, -k2Pi * kPi * y * sTheta, 0.0f ); Vec4 d2pdv2( -kPi * kPi * x, -kPi * kPi * y, -kPi * kPi * z, 0.0f ); // change in normal is computed using Weingarten equations Scalar E = Dot( dpdu, dpdu ); Scalar F = Dot( dpdu, dpdv ); Scalar G = Dot( dpdv, dpdv ); Vec4 N = Normalize( Cross( dpdu, dpdv ) ); Scalar e = Dot( N, d2pdu2 ); Scalar f = Dot( N, d2pduv ); Scalar g = Dot( N, d2pdv2 ); Scalar h = 1.0f / ( E * G - F * F ); Vec4 dndu = ( f * F - e * G ) * h * dpdu + ( e * F - f * E ) * h * dpdv; Vec4 dndv = ( g * F - f * G ) * h * dpdu + ( f * F - g * E ) * h * dpdv; *tHit = t; *epsilon = 5e-4f * t; // return world space differential geometry *geom = DifferentialGeometry( Handle(), p * tf, dpdu * tf, dpdv * tf, Normal( dndu ) * tf, Normal( dndv ) * tf, u, v ); return true; }