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/*
Copyright (c) 2017,2018 Regents of the University of Minnesota.
All Rights Reserved.
See corresponding header file for details.
*/
#include "ray.h"
namespace mingfx {
Ray::Ray() : p_(Point3::Origin()), d_(-Vector3::UnitZ()) {
}
Ray::Ray(const Point3 &origin, const Vector3 &direction) : p_(origin), d_(direction) {
}
Ray::~Ray() {
}
bool Ray::operator==(const Ray& other) const {
return (p_ == other.origin()) && (d_ == other.direction());
}
bool Ray::operator!=(const Ray& other) const {
return (p_ != other.origin()) || (d_ != other.direction());
}
float Ray::Length() const {
return d_.Length();
}
Point3 Ray::origin() const {
return p_;
}
Vector3 Ray::direction() const {
return d_;
}
bool Ray::IntersectPlane(const Point3 &planePt, const Vector3 &planeNormal,
float *iTime, Point3 *iPoint) const
{
float dot = planeNormal.Dot(d_);
// return false if we would hit the back face of the plane
if (dot > 0.0) {
return false;
}
// return false if the ray and plane are parallel
if (std::fabs(dot) < MINGFX_MATH_EPSILON) {
return false;
}
float denom = planeNormal.Dot(d_);
if (std::abs(denom) > MINGFX_MATH_EPSILON) {
*iTime = (planePt - p_).Dot(planeNormal) / denom;
if (*iTime >= 0) {
*iPoint = p_ + (*iTime)*d_;
return true;
}
}
return false;
}
bool Ray::IntersectTriangle(const Point3 &vertex0, const Point3 &vertex1, const Point3 &vertex2,
float *iTime, Point3 *iPoint) const
{
// Implementation of the Möller–Trumbore intersection algorithm
// https://en.wikipedia.org/wiki/M%C3%B6ller%E2%80%93Trumbore_intersection_algorithm
Vector3 edge1, edge2, h, s, q;
float a,f,u,v;
edge1 = vertex1 - vertex0;
edge2 = vertex2 - vertex0;
h = d_.Cross(edge2);
a = edge1.Dot(h);
if (a > -MINGFX_MATH_EPSILON && a < MINGFX_MATH_EPSILON)
return false;
f = 1.f/a;
s = p_ - vertex0;
u = f * (s.Dot(h));
if (u < 0.0 || u > 1.f)
return false;
q = s.Cross(edge1);
v = f * d_.Dot(q);
if ((v < 0.0) || (u + v > 1.0f))
return false;
// At this stage we can compute t to find out where the intersection point is on the line.
*iTime = f * edge2.Dot(q);
if (*iTime > MINGFX_MATH_EPSILON) { // ray intersection
*iPoint = p_ + d_ * (*iTime);
return true;
}
else // This means that there is a line intersection but not a ray intersection.
return false;
/***
// A basic implementation
// find the point of intersection of the ray with the plane of the triangle
Vector3 AB = B - A;
Vector3 AC = C - A;
Vector3 cross = AB.Cross(AC);
Vector3 N = cross.ToUnit();
if (!IntersectPlane(A, N, iTime, iPoint)) {
return false;
}
// check to see if iPoint lies within the triangle
Vector3 edge1 = B - A;
Vector3 v1 = *iPoint - A;
Vector3 check1 = edge1.Cross(v1);
if (N.Dot(check1) < 0.0) {
return false;
}
Vector3 edge2 = C - B;
Vector3 v2 = *iPoint - B;
Vector3 check2 = edge2.Cross(v2);
if (N.Dot(check2) < 0.0) {
return false;
}
Vector3 edge3 = A - C;
Vector3 v3 = *iPoint - C;
Vector3 check3 = edge3.Cross(v3);
if (N.Dot(check3) < 0.0) {
return false;
}
return true;
***/
}
bool Ray::IntersectQuad(const Point3 &A, const Point3 &B, const Point3 &C, const Point3 &D,
float *iTime, Point3 *iPoint) const
{
if (IntersectTriangle(A, B, C, iTime, iPoint)) {
return true;
}
else if (IntersectTriangle(A, C, D, iTime, iPoint)) {
return true;
}
else {
return false;
}
}
bool Ray::IntersectSphere(const Point3 ¢er, float radius,
float *iTime, Point3 *iPoint) const
{
Point3 P = p_ + (Point3::Origin() - center);
Vector3 D = d_;
// A = (Dx^2 + Dy^2 + Dz^2)
const double A = ((double)D[0]*D[0] + (double)D[1]*D[1] + (double)D[2]*D[2]);
// B = (Px * Dx + Py * Dy + Pz * Dz)
const double B = ((double)P[0]*D[0] + (double)P[1]*D[1] + (double)P[2]*D[2]);
// C = (Px^2 + Py^2 + Pz^2 - (sphere radius)^2)
const double C = ((double)P[0]*P[0] + (double)P[1]*P[1] + (double)P[2]*P[2] - (double)radius*radius);
// Discriminant of quadratic = B^2 - A * C
double discriminant = B*B - A*C;
if (discriminant < 0.0) {
return false;
}
else {
double discRoot = sqrt(discriminant);
double t1 = (-B - discRoot) / A;
double t2 = (-B + discRoot) / A;
bool hit1 = false;
bool hit2 = false;
if (t1 > MINGFX_MATH_EPSILON) {
hit1 = true;
*iTime = (float)t1;
}
if (t2 > MINGFX_MATH_EPSILON) {
hit2 = true;
*iTime = (float)t2;
}
if ((!hit1) && (!hit2)) {
return false;
}
if ((hit1) && (hit2)) {
if (t1 < t2) {
*iTime = (float)t1;
}
}
*iPoint = p_ + (*iTime)*d_;
return true;
}
}
bool Ray::IntersectMesh(const Mesh &mesh,
float *iTime, Point3 *iPoint, int *iTriangleID) const
{
*iTime = -1.0;
for (int i=0; i<mesh.num_triangles(); i++) {
Point3 p;
float t;
std::vector<unsigned int> indices = mesh.read_triangle_indices_data(i);
if (IntersectTriangle(mesh.read_vertex_data(indices[0]), mesh.read_vertex_data(indices[1]), mesh.read_vertex_data(indices[2]), &t, &p)) {
if ((*iTime < 0.0) || (t < *iTime)) {
*iPoint = p;
*iTime = t;
*iTriangleID = i;
}
}
}
return (*iTime > 0.0);
}
bool Ray::FastIntersectMesh(Mesh *mesh, float *iTime,
Point3 *iPoint, int *iTriangleID) const
{
std::vector<int> tri_ids = mesh->bvh_ptr()->IntersectAndReturnUserData(*this);
if (tri_ids.size()) {
*iTime = -1.0;
for (int i=0; i<tri_ids.size(); i++) {
Point3 p;
float t;
std::vector<unsigned int> indices = mesh->read_triangle_indices_data(tri_ids[i]);
if (IntersectTriangle(mesh->read_vertex_data(indices[0]), mesh->read_vertex_data(indices[1]), mesh->read_vertex_data(indices[2]), &t, &p)) {
if ((*iTime < 0.0) || (t < *iTime)) {
*iPoint = p;
*iTime = t;
*iTriangleID = i;
}
}
}
return (*iTime > 0.0);
}
else {
return false;
}
}
bool Ray::IntersectAABB(const AABB &box, float *iTime) const {
// https://gamedev.stackexchange.com/questions/18436/most-efficient-aabb-vs-ray-collision-algorithms
Point3 origin = p_;
Vector3 invdir = d_;
invdir[0] = 1.0f / invdir[0];
invdir[1] = 1.0f / invdir[1];
invdir[2] = 1.0f / invdir[2];
float t1 = (box.min()[0] - origin[0])*invdir[0];
float t2 = (box.max()[0] - origin[0])*invdir[0];
float t3 = (box.min()[1] - origin[1])*invdir[1];
float t4 = (box.max()[1] - origin[1])*invdir[1];
float t5 = (box.min()[2] - origin[2])*invdir[2];
float t6 = (box.max()[2] - origin[2])*invdir[2];
float tmin = std::max(std::max(std::min(t1, t2), std::min(t3, t4)), std::min(t5, t6));
float tmax = std::min(std::min(std::max(t1, t2), std::max(t3, t4)), std::max(t5, t6));
// if tmax < 0, ray (line) is intersecting AABB, but the whole AABB is behind us
if (tmax < 0) {
*iTime = tmax;
return false;
}
// if tmin > tmax, ray doesn't intersect AABB
if (tmin > tmax) {
*iTime = tmax;
return false;
}
*iTime = tmin;
return true;
}
void Ray::set(Point3 newOrigin, Vector3 newDir) {
p_ = newOrigin;
d_ = newDir;
}
std::ostream & operator<< ( std::ostream &os, const Ray &r) {
return os << r.origin() << " " << r.direction();
}
std::istream & operator>> ( std::istream &is, Ray &r) {
// format: (x, y, z)
char dummy;
Point3 p;
Vector3 d;
is >> p >> dummy >> d;
r.set(p, d);
return is;
}
} // end namespace
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