void BackgroundActor::UpdateUVs(float horizontal, float vertical)
{
Vector2 lowerLeft;
Vector2 upperRight;
GetUVs(lowerLeft, upperRight);
lowerLeft.X += horizontal;
lowerLeft.Y += vertical;
upperRight.X += horizontal;
upperRight.Y += vertical;
SetUVs(lowerLeft, upperRight);
}
void Triangle::GetShadingGeometry(const Transform &obj2world,
const DifferentialGeometry &dg,
DifferentialGeometry *dgShading) const {
if (!mesh->n && !mesh->s) {
*dgShading = dg;
return;
}
// Initialize _Triangle_ shading geometry with _n_ and _s_
// Compute barycentric coordinates for point
float b[3];
// Initialize _A_ and _C_ matrices for barycentrics
float uv[3][2];
GetUVs(uv);
float A[2][2] =
{ { uv[1][0] - uv[0][0], uv[2][0] - uv[0][0] },
{ uv[1][1] - uv[0][1], uv[2][1] - uv[0][1] } };
float C[2] = { dg.u - uv[0][0], dg.v - uv[0][1] };
if (!SolveLinearSystem2x2(A, C, &b[1], &b[2])) {
// Handle degenerate parametric mapping
b[0] = b[1] = b[2] = 1.f/3.f;
}
else
b[0] = 1.f - b[1] - b[2];
// Use _n_ and _s_ to compute shading tangents for triangle, _ss_ and _ts_
Normal ns;
Vector ss, ts;
if (mesh->n) ns = Normalize(obj2world(b[0] * mesh->n[v[0]] +
b[1] * mesh->n[v[1]] +
b[2] * mesh->n[v[2]]));
else ns = dg.nn;
if (mesh->s) ss = Normalize(obj2world(b[0] * mesh->s[v[0]] +
b[1] * mesh->s[v[1]] +
b[2] * mesh->s[v[2]]));
else ss = Normalize(dg.dpdu);
ts = Cross(ss, ns);
if (ts.LengthSquared() > 0.f) {
ts = Normalize(ts);
ss = Cross(ts, ns);
}
else
CoordinateSystem((Vector)ns, &ss, &ts);
Normal dndu, dndv;
// Compute $\dndu$ and $\dndv$ for triangle shading geometry
if (mesh->n) {
float uvs[3][2];
GetUVs(uvs);
// Compute deltas for triangle partial derivatives of normal
float du1 = uvs[0][0] - uvs[2][0];
float du2 = uvs[1][0] - uvs[2][0];
float dv1 = uvs[0][1] - uvs[2][1];
float dv2 = uvs[1][1] - uvs[2][1];
Normal dn1 = mesh->n[v[0]] - mesh->n[v[2]];
Normal dn2 = mesh->n[v[1]] - mesh->n[v[2]];
float determinant = du1 * dv2 - dv1 * du2;
if (determinant == 0.f)
dndu = dndv = Normal(0,0,0);
else {
float invdet = 1.f / determinant;
dndu = ( dv2 * dn1 - dv1 * dn2) * invdet;
dndv = (-du2 * dn1 + du1 * dn2) * invdet;
}
}
else
dndu = dndv = Normal(0,0,0);
*dgShading = DifferentialGeometry(dg.p, ss, ts,
(*ObjectToWorld)(dndu), (*ObjectToWorld)(dndv),
dg.u, dg.v, dg.shape);
dgShading->dudx = dg.dudx; dgShading->dvdx = dg.dvdx;
dgShading->dudy = dg.dudy; dgShading->dvdy = dg.dvdy;
dgShading->dpdx = dg.dpdx; dgShading->dpdy = dg.dpdy;
}
bool Triangle::IntersectP(const Ray &ray) const {
PBRT_RAY_TRIANGLE_INTERSECTIONP_TEST(const_cast<Ray *>(&ray), const_cast<Triangle *>(this));
// Compute $\VEC{s}_1$
// Get triangle vertices in _p1_, _p2_, and _p3_
const Point &p1 = mesh->p[v[0]];
const Point &p2 = mesh->p[v[1]];
const Point &p3 = mesh->p[v[2]];
Vector e1 = p2 - p1;
Vector e2 = p3 - p1;
Vector s1 = Cross(ray.d, e2);
float divisor = Dot(s1, e1);
if (divisor == 0.)
return false;
float invDivisor = 1.f / divisor;
// Compute first barycentric coordinate
Vector d = ray.o - p1;
float b1 = Dot(d, s1) * invDivisor;
if (b1 < 0. || b1 > 1.)
return false;
// Compute second barycentric coordinate
Vector s2 = Cross(d, e1);
float b2 = Dot(ray.d, s2) * invDivisor;
if (b2 < 0. || b1 + b2 > 1.)
return false;
// Compute _t_ to intersection point
float t = Dot(e2, s2) * invDivisor;
if (t < ray.mint || t > ray.maxt)
return false;
// Test shadow ray intersection against alpha texture, if present
if (ray.depth != -1 && mesh->alphaTexture) {
// Compute triangle partial derivatives
Vector dpdu, dpdv;
float uvs[3][2];
GetUVs(uvs);
// Compute deltas for triangle partial derivatives
float du1 = uvs[0][0] - uvs[2][0];
float du2 = uvs[1][0] - uvs[2][0];
float dv1 = uvs[0][1] - uvs[2][1];
float dv2 = uvs[1][1] - uvs[2][1];
Vector dp1 = p1 - p3, dp2 = p2 - p3;
float determinant = du1 * dv2 - dv1 * du2;
if (determinant == 0.f) {
// Handle zero determinant for triangle partial derivative matrix
CoordinateSystem(Normalize(Cross(e2, e1)), &dpdu, &dpdv);
}
else {
float invdet = 1.f / determinant;
dpdu = ( dv2 * dp1 - dv1 * dp2) * invdet;
dpdv = (-du2 * dp1 + du1 * dp2) * invdet;
}
// Interpolate $(u,v)$ triangle parametric coordinates
float b0 = 1 - b1 - b2;
float tu = b0*uvs[0][0] + b1*uvs[1][0] + b2*uvs[2][0];
float tv = b0*uvs[0][1] + b1*uvs[1][1] + b2*uvs[2][1];
DifferentialGeometry dgLocal(ray(t), dpdu, dpdv,
Normal(0,0,0), Normal(0,0,0),
tu, tv, this);
if (mesh->alphaTexture->Evaluate(dgLocal) == 0.f)
return false;
}
PBRT_RAY_TRIANGLE_INTERSECTIONP_HIT(const_cast<Ray *>(&ray), t);
return true;
}
bool Triangle::Intersect(const Ray &ray, Float *distance, Float *rayEpsilon,
DifferentialGeometry *dg) const {
Point p1 = mMesh->p[mIndex[0]];
Point p2 = mMesh->p[mIndex[1]];
Point p3 = mMesh->p[mIndex[2]];
//这里使用质心坐标来计算 详见PBRT公式
Vector3f e1 = p2 - p1; //e1=p2-p1
Vector3f e2 = p3 - p1; //e2=p3-p1
Vector3f s1 = Cross(ray.d, e2); //s1=d x e2
Float divisor = Dot(s1, e1);
if (divisor == 0.0f)
return false;
Float invDivisor = 1.f / divisor; //1/(s1.e1)
// 计算第一个质心坐标
Vector3f s = ray.o - p1; //s = o - p1
Float b1 = Dot(s, s1) * invDivisor; //b1 = (s.s1)/(s1.e1)
if (b1 < 0. || b1 > 1.)
return false;
// 计算第二个质心坐标
Vector3f s2 = Cross(s, e1); //s2 = s x e1
Float b2 = Dot(ray.d, s2) * invDivisor; // b2 = (d.s2)/(s1.e1)
if (b2 < 0. || b1 + b2 > 1.)
return false;
// 计算参数t
Float t = Dot(e2, s2) * invDivisor;
if (t < ray.minT || t > ray.maxT)
return false;
Vector3f dpdu, dpdv; //p在u和v上的偏导
Float uvs[3][2];
GetUVs(uvs);
//计算p在u和v上的偏导
Float du1 = uvs[0][0] - uvs[2][0];
Float du2 = uvs[1][0] - uvs[2][0];
Float dv1 = uvs[0][1] - uvs[2][1];
Float dv2 = uvs[1][1] - uvs[2][1];
Vector3f dp1 = p1 - p3, dp2 = p2 - p3;
Float determinant = du1 * dv2 - dv1 * du2;
if (determinant == 0.f) {
//行列式为0
CoordinateSystem(Normalize(Cross(e2, e1)), &dpdu, &dpdv);
} else {
Float invdet = 1.f / determinant;
dpdu = (dv2 * dp1 - dv1 * dp2) * invdet;
dpdv = (-du2 * dp1 + du1 * dp2) * invdet;
}
//这里是在计算参数坐标 用的也是质心坐标
Float b0 = 1 - b1 - b2;
Float tu = b0 * uvs[0][0] + b1 * uvs[1][0] + b2 * uvs[2][0];
Float tv = b0 * uvs[0][1] + b1 * uvs[1][1] + b2 * uvs[2][1];
*dg = DifferentialGeometry(ray(t), dpdu, dpdv, Normal(0, 0, 0),
Normal(0, 0, 0), tu, tv, this);
*distance = t;
*rayEpsilon = 1e-3f * *distance;
//cout<<"射中三角"<<endl;
return true;
}
bool NaiadTriangle::Intersect(const Ray &ray, float *tHit, float *rayEpsilon,
DifferentialGeometry *dg) const {
if (!mesh.GetPtr()->foam_block && ray.zbuffer) return false;
PBRT_RAY_TRIANGLE_INTERSECTION_TEST(const_cast<Ray *>(&ray), const_cast<NaiadTriangle *>(this));
// Compute $\VEC{s}_1$
// Get NaiadTriangle vertices in _p1_, _p2_, and _p3_
const Point &p1 = mesh->p[v[0]];
const Point &p2 = mesh->p[v[1]];
const Point &p3 = mesh->p[v[2]];
Vector e1 = p2 - p1;
Vector e2 = p3 - p1;
Vector s1 = Cross(ray.d, e2);
float divisor = Dot(s1, e1);
if (divisor == 0.)
return false;
float invDivisor = 1.f / divisor;
// Compute first barycentric coordinate
Vector d = ray.o - p1;
float b1 = Dot(d, s1) * invDivisor;
if (b1 < 0. || b1 > 1.)
return false;
// Compute second barycentric coordinate
Vector s2 = Cross(d, e1);
float b2 = Dot(ray.d, s2) * invDivisor;
if (b2 < 0. || b1 + b2 > 1.)
return false;
// Compute _t_ to intersection point
float t = Dot(e2, s2) * invDivisor;
if (t < ray.mint || t > ray.maxt)
return false;
// Compute NaiadTriangle partial derivatives
Vector dpdu, dpdv;
float uvs[3][2];
GetUVs(uvs);
// Compute deltas for NaiadTriangle partial derivatives
float du1 = uvs[0][0] - uvs[2][0];
float du2 = uvs[1][0] - uvs[2][0];
float dv1 = uvs[0][1] - uvs[2][1];
float dv2 = uvs[1][1] - uvs[2][1];
Vector dp1 = p1 - p3, dp2 = p2 - p3;
float determinant = du1 * dv2 - dv1 * du2;
if (determinant == 0.f) {
// Handle zero determinant for NaiadTriangle partial derivative matrix
CoordinateSystem(Normalize(Cross(e2, e1)), &dpdu, &dpdv);
}
else {
float invdet = 1.f / determinant;
dpdu = ( dv2 * dp1 - dv1 * dp2) * invdet;
dpdv = (-du2 * dp1 + du1 * dp2) * invdet;
}
// Interpolate $(u,v)$ NaiadTriangle parametric coordinates
float b0 = 1 - b1 - b2;
float tu = b0*uvs[0][0] + b1*uvs[1][0] + b2*uvs[2][0];
float tv = b0*uvs[0][1] + b1*uvs[1][1] + b2*uvs[2][1];
//printf("\nu: %f, v: %f\n",tu,tv);
// Test intersection against alpha texture, if present
if (ray.depth != -1) {
if (mesh->alphaTexture) {
DifferentialGeometry dgLocal(ray(t), dpdu, dpdv,
Normal(0,0,0), Normal(0,0,0),
tu, tv, this);
if (mesh->alphaTexture->Evaluate(dgLocal) == 0.f)
return false;
}
}
// Fill in _DifferentialGeometry_ from NaiadTriangle hit
*dg = DifferentialGeometry(ray(t), dpdu, dpdv,
Normal(0,0,0), Normal(0,0,0),
tu, tv, this);
*tHit = t;
//If writing to Z buffer
if (mesh.GetPtr()->foam_block ) {
ray.zbuffer_depth = t;
}
*rayEpsilon = 1e-3f * *tHit;
PBRT_RAY_TRIANGLE_INTERSECTION_HIT(const_cast<Ray *>(&ray), t);
return true;
}
bool Triangle::IntersectP(const Ray &ray, bool testAlphaTexture) const {
ProfilePhase p(Prof::TriIntersectP);
++nTests;
// Get triangle vertices in _p0_, _p1_, and _p2_
const Point3f &p0 = mesh->p[v[0]];
const Point3f &p1 = mesh->p[v[1]];
const Point3f &p2 = mesh->p[v[2]];
// Perform ray--triangle intersection test
// Transform triangle vertices to ray coordinate space
// Translate vertices based on ray origin
Point3f p0t = p0 - Vector3f(ray.o);
Point3f p1t = p1 - Vector3f(ray.o);
Point3f p2t = p2 - Vector3f(ray.o);
// Permute components of triangle vertices and ray direction
int kz = MaxDimension(Abs(ray.d));
int kx = kz + 1;
if (kx == 3) kx = 0;
int ky = kx + 1;
if (ky == 3) ky = 0;
Vector3f d = Permute(ray.d, kx, ky, kz);
p0t = Permute(p0t, kx, ky, kz);
p1t = Permute(p1t, kx, ky, kz);
p2t = Permute(p2t, kx, ky, kz);
// Apply shear transformation to translated vertex positions
Float Sx = -d.x / d.z;
Float Sy = -d.y / d.z;
Float Sz = 1.f / d.z;
p0t.x += Sx * p0t.z;
p0t.y += Sy * p0t.z;
p1t.x += Sx * p1t.z;
p1t.y += Sy * p1t.z;
p2t.x += Sx * p2t.z;
p2t.y += Sy * p2t.z;
// Compute edge function coefficients _e0_, _e1_, and _e2_
Float e0 = p1t.x * p2t.y - p1t.y * p2t.x;
Float e1 = p2t.x * p0t.y - p2t.y * p0t.x;
Float e2 = p0t.x * p1t.y - p0t.y * p1t.x;
// Fall back to double precision test at triangle edges
if (sizeof(Float) == sizeof(float) &&
(e0 == 0.0f || e1 == 0.0f || e2 == 0.0f)) {
double p2txp1ty = (double)p2t.x * (double)p1t.y;
double p2typ1tx = (double)p2t.y * (double)p1t.x;
e0 = (float)(p2typ1tx - p2txp1ty);
double p0txp2ty = (double)p0t.x * (double)p2t.y;
double p0typ2tx = (double)p0t.y * (double)p2t.x;
e1 = (float)(p0typ2tx - p0txp2ty);
double p1txp0ty = (double)p1t.x * (double)p0t.y;
double p1typ0tx = (double)p1t.y * (double)p0t.x;
e2 = (float)(p1typ0tx - p1txp0ty);
}
// Perform triangle edge and determinant tests
if ((e0 < 0 || e1 < 0 || e2 < 0) && (e0 > 0 || e1 > 0 || e2 > 0))
return false;
Float det = e0 + e1 + e2;
if (det == 0) return false;
// Compute scaled hit distance to triangle and test against ray $t$ range
p0t.z *= Sz;
p1t.z *= Sz;
p2t.z *= Sz;
Float tScaled = e0 * p0t.z + e1 * p1t.z + e2 * p2t.z;
if (det < 0 && (tScaled >= 0 || tScaled < ray.tMax * det))
return false;
else if (det > 0 && (tScaled <= 0 || tScaled > ray.tMax * det))
return false;
// Compute barycentric coordinates and $t$ value for triangle intersection
Float invDet = 1 / det;
Float b0 = e0 * invDet;
Float b1 = e1 * invDet;
Float b2 = e2 * invDet;
Float t = tScaled * invDet;
// Ensure that computed triangle $t$ is conservatively greater than zero
// Compute $\delta_z$ term for triangle $t$ error bounds
Float maxZt = MaxComponent(Abs(Vector3f(p0t.z, p1t.z, p2t.z)));
Float deltaZ = gamma(3) * maxZt;
// Compute $\delta_x$ and $\delta_y$ terms for triangle $t$ error bounds
Float maxXt = MaxComponent(Abs(Vector3f(p0t.x, p1t.x, p2t.x)));
Float maxYt = MaxComponent(Abs(Vector3f(p0t.y, p1t.y, p2t.y)));
Float deltaX = gamma(5) * (maxXt + maxZt);
Float deltaY = gamma(5) * (maxYt + maxZt);
// Compute $\delta_e$ term for triangle $t$ error bounds
Float deltaE =
2 * (gamma(2) * maxXt * maxYt + deltaY * maxXt + deltaX * maxYt);
// Compute $\delta_t$ term for triangle $t$ error bounds and check _t_
Float maxE = MaxComponent(Abs(Vector3f(e0, e1, e2)));
Float deltaT = 3 *
(gamma(3) * maxE * maxZt + deltaE * maxZt + deltaZ * maxE) *
std::abs(invDet);
if (t <= deltaT) return false;
// Test shadow ray intersection against alpha texture, if present
if (testAlphaTexture && (mesh->alphaMask || mesh->shadowAlphaMask)) {
// Compute triangle partial derivatives
Vector3f dpdu, dpdv;
Point2f uv[3];
GetUVs(uv);
// Compute deltas for triangle partial derivatives
Vector2f duv02 = uv[0] - uv[2], duv12 = uv[1] - uv[2];
Vector3f dp02 = p0 - p2, dp12 = p1 - p2;
Float determinant = duv02[0] * duv12[1] - duv02[1] * duv12[0];
if (determinant == 0) {
// Handle zero determinant for triangle partial derivative matrix
CoordinateSystem(Normalize(Cross(p2 - p0, p1 - p0)), &dpdu, &dpdv);
} else {
Float invdet = 1 / determinant;
dpdu = (duv12[1] * dp02 - duv02[1] * dp12) * invdet;
dpdv = (-duv12[0] * dp02 + duv02[0] * dp12) * invdet;
}
// Interpolate $(u,v)$ parametric coordinates and hit point
Point3f pHit = b0 * p0 + b1 * p1 + b2 * p2;
Point2f uvHit = b0 * uv[0] + b1 * uv[1] + b2 * uv[2];
SurfaceInteraction isectLocal(pHit, Vector3f(0, 0, 0), uvHit, -ray.d,
dpdu, dpdv, Normal3f(0, 0, 0),
Normal3f(0, 0, 0), ray.time, this);
if (mesh->alphaMask && mesh->alphaMask->Evaluate(isectLocal) == 0)
return false;
if (mesh->shadowAlphaMask &&
mesh->shadowAlphaMask->Evaluate(isectLocal) == 0)
return false;
}
++nHits;
return true;
}
bool Triangle::Intersect(const Ray &ray, Float *tHit, SurfaceInteraction *isect,
bool testAlphaTexture) const {
ProfilePhase p(Prof::TriIntersect);
++nTests;
// Get triangle vertices in _p0_, _p1_, and _p2_
const Point3f &p0 = mesh->p[v[0]];
const Point3f &p1 = mesh->p[v[1]];
const Point3f &p2 = mesh->p[v[2]];
// Perform ray--triangle intersection test
// Transform triangle vertices to ray coordinate space
// Translate vertices based on ray origin
Point3f p0t = p0 - Vector3f(ray.o);
Point3f p1t = p1 - Vector3f(ray.o);
Point3f p2t = p2 - Vector3f(ray.o);
// Permute components of triangle vertices and ray direction
int kz = MaxDimension(Abs(ray.d));
int kx = kz + 1;
if (kx == 3) kx = 0;
int ky = kx + 1;
if (ky == 3) ky = 0;
Vector3f d = Permute(ray.d, kx, ky, kz);
p0t = Permute(p0t, kx, ky, kz);
p1t = Permute(p1t, kx, ky, kz);
p2t = Permute(p2t, kx, ky, kz);
// Apply shear transformation to translated vertex positions
Float Sx = -d.x / d.z;
Float Sy = -d.y / d.z;
Float Sz = 1.f / d.z;
p0t.x += Sx * p0t.z;
p0t.y += Sy * p0t.z;
p1t.x += Sx * p1t.z;
p1t.y += Sy * p1t.z;
p2t.x += Sx * p2t.z;
p2t.y += Sy * p2t.z;
// Compute edge function coefficients _e0_, _e1_, and _e2_
Float e0 = p1t.x * p2t.y - p1t.y * p2t.x;
Float e1 = p2t.x * p0t.y - p2t.y * p0t.x;
Float e2 = p0t.x * p1t.y - p0t.y * p1t.x;
// Fall back to double precision test at triangle edges
if (sizeof(Float) == sizeof(float) &&
(e0 == 0.0f || e1 == 0.0f || e2 == 0.0f)) {
double p2txp1ty = (double)p2t.x * (double)p1t.y;
double p2typ1tx = (double)p2t.y * (double)p1t.x;
e0 = (float)(p2typ1tx - p2txp1ty);
double p0txp2ty = (double)p0t.x * (double)p2t.y;
double p0typ2tx = (double)p0t.y * (double)p2t.x;
e1 = (float)(p0typ2tx - p0txp2ty);
double p1txp0ty = (double)p1t.x * (double)p0t.y;
double p1typ0tx = (double)p1t.y * (double)p0t.x;
e2 = (float)(p1typ0tx - p1txp0ty);
}
// Perform triangle edge and determinant tests
if ((e0 < 0 || e1 < 0 || e2 < 0) && (e0 > 0 || e1 > 0 || e2 > 0))
return false;
Float det = e0 + e1 + e2;
if (det == 0) return false;
// Compute scaled hit distance to triangle and test against ray $t$ range
p0t.z *= Sz;
p1t.z *= Sz;
p2t.z *= Sz;
Float tScaled = e0 * p0t.z + e1 * p1t.z + e2 * p2t.z;
if (det < 0 && (tScaled >= 0 || tScaled < ray.tMax * det))
return false;
else if (det > 0 && (tScaled <= 0 || tScaled > ray.tMax * det))
return false;
// Compute barycentric coordinates and $t$ value for triangle intersection
Float invDet = 1 / det;
Float b0 = e0 * invDet;
Float b1 = e1 * invDet;
Float b2 = e2 * invDet;
Float t = tScaled * invDet;
// Ensure that computed triangle $t$ is conservatively greater than zero
// Compute $\delta_z$ term for triangle $t$ error bounds
Float maxZt = MaxComponent(Abs(Vector3f(p0t.z, p1t.z, p2t.z)));
Float deltaZ = gamma(3) * maxZt;
// Compute $\delta_x$ and $\delta_y$ terms for triangle $t$ error bounds
Float maxXt = MaxComponent(Abs(Vector3f(p0t.x, p1t.x, p2t.x)));
Float maxYt = MaxComponent(Abs(Vector3f(p0t.y, p1t.y, p2t.y)));
Float deltaX = gamma(5) * (maxXt + maxZt);
Float deltaY = gamma(5) * (maxYt + maxZt);
// Compute $\delta_e$ term for triangle $t$ error bounds
Float deltaE =
2 * (gamma(2) * maxXt * maxYt + deltaY * maxXt + deltaX * maxYt);
// Compute $\delta_t$ term for triangle $t$ error bounds and check _t_
Float maxE = MaxComponent(Abs(Vector3f(e0, e1, e2)));
Float deltaT = 3 *
(gamma(3) * maxE * maxZt + deltaE * maxZt + deltaZ * maxE) *
std::abs(invDet);
if (t <= deltaT) return false;
// Compute triangle partial derivatives
Vector3f dpdu, dpdv;
Point2f uv[3];
GetUVs(uv);
// Compute deltas for triangle partial derivatives
Vector2f duv02 = uv[0] - uv[2], duv12 = uv[1] - uv[2];
Vector3f dp02 = p0 - p2, dp12 = p1 - p2;
Float determinant = duv02[0] * duv12[1] - duv02[1] * duv12[0];
if (determinant == 0) {
// Handle zero determinant for triangle partial derivative matrix
CoordinateSystem(Normalize(Cross(p2 - p0, p1 - p0)), &dpdu, &dpdv);
} else {
Float invdet = 1 / determinant;
dpdu = (duv12[1] * dp02 - duv02[1] * dp12) * invdet;
dpdv = (-duv12[0] * dp02 + duv02[0] * dp12) * invdet;
}
// Compute error bounds for triangle intersection
Float xAbsSum =
(std::abs(b0 * p0.x) + std::abs(b1 * p1.x) + std::abs(b2 * p2.x));
Float yAbsSum =
(std::abs(b0 * p0.y) + std::abs(b1 * p1.y) + std::abs(b2 * p2.y));
Float zAbsSum =
(std::abs(b0 * p0.z) + std::abs(b1 * p1.z) + std::abs(b2 * p2.z));
Vector3f pError = gamma(7) * Vector3f(xAbsSum, yAbsSum, zAbsSum);
// Interpolate $(u,v)$ parametric coordinates and hit point
Point3f pHit = b0 * p0 + b1 * p1 + b2 * p2;
Point2f uvHit = b0 * uv[0] + b1 * uv[1] + b2 * uv[2];
// Test intersection against alpha texture, if present
if (testAlphaTexture && mesh->alphaMask) {
SurfaceInteraction isectLocal(pHit, Vector3f(0, 0, 0), uvHit, -ray.d,
dpdu, dpdv, Normal3f(0, 0, 0),
Normal3f(0, 0, 0), ray.time, this);
if (mesh->alphaMask->Evaluate(isectLocal) == 0) return false;
}
// Fill in _SurfaceInteraction_ from triangle hit
*isect = SurfaceInteraction(pHit, pError, uvHit, -ray.d, dpdu, dpdv,
Normal3f(0, 0, 0), Normal3f(0, 0, 0), ray.time,
this);
// Override surface normal in _isect_ for triangle
isect->n = isect->shading.n = Normal3f(Normalize(Cross(dp02, dp12)));
if (mesh->n || mesh->s) {
// Initialize _Triangle_ shading geometry
// Compute shading normal _ns_ for triangle
Normal3f ns;
if (mesh->n) {
ns = (b0 * mesh->n[v[0]] + b1 * mesh->n[v[1]] +
b2 * mesh->n[v[2]]);
if (ns.LengthSquared() > 0)
ns = Normalize(ns);
else
ns = isect->n;
} else
ns = isect->n;
// Compute shading tangent _ss_ for triangle
Vector3f ss;
if (mesh->s) {
ss = (b0 * mesh->s[v[0]] + b1 * mesh->s[v[1]] +
b2 * mesh->s[v[2]]);
if (ss.LengthSquared() > 0)
ss = Normalize(ss);
else
ss = Normalize(isect->dpdu);
}
else
ss = Normalize(isect->dpdu);
// Compute shading bitangent _ts_ for triangle and adjust _ss_
Vector3f ts = Cross(ss, ns);
if (ts.LengthSquared() > 0.f) {
ts = Normalize(ts);
ss = Cross(ts, ns);
} else
CoordinateSystem((Vector3f)ns, &ss, &ts);
// Compute $\dndu$ and $\dndv$ for triangle shading geometry
Normal3f dndu, dndv;
if (mesh->n) {
// Compute deltas for triangle partial derivatives of normal
Vector2f duv02 = uv[0] - uv[2];
Vector2f duv12 = uv[1] - uv[2];
Normal3f dn1 = mesh->n[v[0]] - mesh->n[v[2]];
Normal3f dn2 = mesh->n[v[1]] - mesh->n[v[2]];
Float determinant = duv02[0] * duv12[1] - duv02[1] * duv12[0];
if (determinant == 0)
dndu = dndv = Normal3f(0, 0, 0);
else {
Float invDet = 1 / determinant;
dndu = (duv12[1] * dn1 - duv02[1] * dn2) * invDet;
dndv = (-duv12[0] * dn1 + duv02[0] * dn2) * invDet;
}
} else
dndu = dndv = Normal3f(0, 0, 0);
isect->SetShadingGeometry(ss, ts, dndu, dndv, true);
}
// Ensure correct orientation of the geometric normal
if (mesh->n)
isect->n = Faceforward(isect->n, isect->shading.n);
else if (reverseOrientation ^ transformSwapsHandedness)
isect->n = isect->shading.n = -isect->n;
*tHit = t;
++nHits;
return true;
}
std::shared_ptr<Mesh> FBXConverter::LoadMesh(FbxMesh* fbxMesh)
{
assert(fbxMesh->GetLayerCount() > 0);
auto node = fbxMesh->GetNode();
auto layer = fbxMesh->GetLayer(0);
if (layer->GetNormals() == nullptr)
{
fbxMesh->GenerateNormals(true);
}
auto uvs = layer->GetUVs();
auto vcolors = layer->GetVertexColors();
auto normals = layer->GetNormals();
auto binormals = layer->GetBinormals();
auto materials = layer->GetMaterials();
auto controlPoints = fbxMesh->GetControlPoints();
auto controlPointsCount = fbxMesh->GetControlPointsCount();
auto polygonCount = fbxMesh->GetPolygonCount();
std::vector<FbxFace> faces;
// Load weights
std::vector<BoneConnector> bcs_temp;
std::vector<Vertex> vs_temp;
LoadSkin(fbxMesh, bcs_temp, vs_temp);
// generate face vertex
int32_t vertexID = 0;
for (int32_t polygonIndex = 0; polygonIndex < polygonCount; polygonIndex++)
{
int polygonPointCount = fbxMesh->GetPolygonSize(polygonIndex);
FbxFace face;
for (int32_t polygonPointIndex = 0; polygonPointIndex < polygonPointCount; polygonPointIndex++)
{
auto ctrlPointIndex = fbxMesh->GetPolygonVertex(polygonIndex, polygonPointIndex);
Vertex v;
v.Position = LoadPosition(fbxMesh, ctrlPointIndex);
v.Weights = vs_temp[ctrlPointIndex].Weights;
if (normals != nullptr)
{
v.Normal = LoadNormal(normals, vertexID, ctrlPointIndex);
}
if (uvs != nullptr)
{
v.UV = LoadUV(fbxMesh, uvs, vertexID, ctrlPointIndex, polygonIndex, polygonPointIndex);
}
else
{
// Auto generated
v.UV[0] = v.Position[0] + v.Position[2];
v.UV[1] = v.Position[1];
}
if (vcolors != nullptr)
{
v.VertexColor = LoadVertexColor(fbxMesh, vcolors, vertexID, ctrlPointIndex, polygonIndex, polygonPointIndex);
}
face.Vertecies.push_back(v);
vertexID++;
}
faces.push_back(face);
}
// 面の表裏入れ替え
for (auto& face : faces)
{
std::reverse(face.Vertecies.begin(), face.Vertecies.end());
}
// メッシュで使用可能な形式に変換
// 頂点変換テーブル作成
int32_t vInd = 0;
std::map<Vertex, int32_t> v2ind;
std::map<int32_t, Vertex> ind2v;
for (auto& face : faces)
{
for (int32_t vi = 0; vi < (int32_t)face.Vertecies.size(); vi++)
{
auto vertex = face.Vertecies[vi];
auto it = v2ind.find(vertex);
if (it == v2ind.end())
{
v2ind[vertex] = vInd;
ind2v[vInd] = vertex;
vInd++;
}
}
}
// 設定
auto mesh = std::make_shared<Mesh>();
mesh->Name = node->GetName();
mesh->BoneConnectors = bcs_temp;
mesh->Vertexes.resize(vInd);
for (auto& iv : ind2v)
{
mesh->Vertexes[iv.first] = iv.second;
}
for (auto& face : faces)
{
if (face.Vertecies.size() < 3) continue;
if (face.Vertecies.size() == 3)
{
Face f;
f.Index[0] = v2ind[face.Vertecies[0]];
f.Index[1] = v2ind[face.Vertecies[1]];
f.Index[2] = v2ind[face.Vertecies[2]];
mesh->Faces.push_back(f);
}
if (face.Vertecies.size() == 4)
{
Face f0;
f0.Index[0] = v2ind[face.Vertecies[0]];
f0.Index[1] = v2ind[face.Vertecies[1]];
f0.Index[2] = v2ind[face.Vertecies[2]];
mesh->Faces.push_back(f0);
Face f1;
f1.Index[0] = v2ind[face.Vertecies[0]];
f1.Index[1] = v2ind[face.Vertecies[2]];
f1.Index[2] = v2ind[face.Vertecies[3]];
mesh->Faces.push_back(f1);
}
}
// Binormal,Tangent計算
std::map<int32_t, VertexNormals> vInd2Normals;
for (const auto& face : mesh->Faces)
{
FbxVector4 binormal, tangent;
CalcTangentSpace(
mesh->Vertexes[face.Index[0]],
mesh->Vertexes[face.Index[1]],
mesh->Vertexes[face.Index[2]],
binormal,
tangent);
for (auto i = 0; i < 3; i++)
{
vInd2Normals[face.Index[i]].Binormal += binormal;
vInd2Normals[face.Index[i]].Tangent += tangent;
vInd2Normals[face.Index[i]].Count += 1;
}
}
for (auto& vn : vInd2Normals)
{
vn.second.Binormal /= vn.second.Count;
vn.second.Tangent /= vn.second.Count;
}
for (auto& vn : vInd2Normals)
{
mesh->Vertexes[vn.first].Binormal = vn.second.Binormal;
mesh->Vertexes[vn.first].Tangent = vn.second.Tangent;
// 適当な値を代入する
if (mesh->Vertexes[vn.first].Binormal.Length() == 0.0f)
{
if (mesh->Vertexes[vn.first].Normal != FbxVector4(1, 0, 0))
{
mesh->Vertexes[vn.first].Binormal = FbxVector4(1, 0, 0);
mesh->Vertexes[vn.first].Tangent = FbxVector4(0, 1, 0);
}
else
{
mesh->Vertexes[vn.first].Binormal = FbxVector4(0, 1, 0);
mesh->Vertexes[vn.first].Tangent = FbxVector4(1, 0, 0);
}
}
}
return mesh;
}