You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
212 lines
8.2 KiB
212 lines
8.2 KiB
#pragma once
|
|
|
|
|
|
#include <numeric>
|
|
#include <algorithm>
|
|
#include <vector>
|
|
#include <cstddef>
|
|
#include "Geometry.h"
|
|
|
|
struct TriangleSegmentIntersectRes {
|
|
bool hit;
|
|
float t;
|
|
TriangleSegmentIntersectRes(bool h,float tt):hit(h),t(tt){}//VS2008
|
|
};
|
|
|
|
TriangleSegmentIntersectRes
|
|
triangleSegmentIntersection(const LineSegment &segment, const Vec3f &a, const Vec3f &b, const Vec3f &c) {
|
|
Vec3f e1 = b - a;
|
|
Vec3f e2 = c - a;
|
|
Vec3f s = segment.start - a;
|
|
Vec3f s1 = segment.getDir().cross(e2);
|
|
Vec3f s2 = s.cross(e1);
|
|
float s1_dot_e1 = s1.dot(e1);
|
|
float b1 = s1.dot(s) / s1_dot_e1;
|
|
float b2 = s2.dot(segment.getDir()) / s1_dot_e1;
|
|
if (b1 >= 0. && b2 >= 0. && b1 + b2 <= 1.) {
|
|
// hit
|
|
// return {true, s2.dot(e2) / s1_dot_e1};
|
|
return TriangleSegmentIntersectRes(true, s2.dot(e2) / s1_dot_e1);//VS2008
|
|
}
|
|
// return {false, 0.};
|
|
return TriangleSegmentIntersectRes(false, 0.f);//VS2008
|
|
}
|
|
|
|
class BVHNode {
|
|
public:
|
|
size_t left;
|
|
size_t right;
|
|
size_t parent;
|
|
AABB boundingBox;
|
|
|
|
BVHNode(size_t l, size_t r, size_t p, const AABB &aabb) : left(l), right(r), parent(p), boundingBox(aabb) {}
|
|
BVHNode() : left(0), right(0), parent(0), boundingBox() {}
|
|
};
|
|
|
|
|
|
class BVH_intersection {
|
|
public:
|
|
const Mesh &mesh;
|
|
std::vector<Vec3f> faceCenters;
|
|
std::vector<BVHNode> nodes;
|
|
|
|
BVH_intersection(const Mesh &mesh_) : mesh(mesh_) {
|
|
faceCenters.reserve(mesh.indices.size());
|
|
// for (const Vec3u &face: mesh.indices) {
|
|
// Vec3f center = (mesh.vertices[face[0]] + mesh.vertices[face[1]] + mesh.vertices[face[2]]) / 3.0f;
|
|
// faceCenters.push_back(center);
|
|
// }
|
|
for (std::vector<Vec3u>::const_iterator it = mesh.indices.begin();it!=mesh.indices.end();++it) {
|
|
const Vec3u& face = *it;
|
|
Vec3f center = (mesh.vertices[face[0]] + mesh.vertices[face[1]] + mesh.vertices[face[2]]) / 3.0f;
|
|
faceCenters.push_back(center);
|
|
}//VS2008
|
|
std::vector<size_t> indicesList(mesh.indices.size());
|
|
// std::iota(indicesList.begin(), indicesList.end(), 0);
|
|
for(size_t i=0;i<indicesList.size();++i){
|
|
indicesList[i]=i;
|
|
}//��������
|
|
try{
|
|
nodes.resize(2 * mesh.indices.size() - 1);
|
|
}catch(const std::length_error& e){
|
|
std::cout<<"vector.length:"<<nodes.size()<<" resize_pa:"<<(2 * mesh.indices.size() - 1)<<std::endl;
|
|
std::cerr<<"Caught a length_error: "<<e.what()<<std::endl;
|
|
}
|
|
//nodes.resize(2 * mesh.indices.size() - 1);
|
|
|
|
size_t nowIdx = 0;
|
|
dfsBuild(indicesList, computeAABB(indicesList), nowIdx);
|
|
}
|
|
|
|
size_t
|
|
dfsBuild(std::vector<size_t> &indicesList, AABB aabb, size_t &nowIdx) {
|
|
const size_t nodeIdx = nowIdx;
|
|
nowIdx++;
|
|
if (indicesList.size() == 1) {
|
|
// leaf
|
|
// nodes[nodeIdx] = {0, indicesList[0], 0, aabb};
|
|
nodes[nodeIdx] = BVHNode(0, indicesList[0], 0, aabb);//VS2008
|
|
return nodeIdx;
|
|
}
|
|
// longest axis
|
|
int longAxis = -1;
|
|
float longAxisLen = -1;
|
|
for (int i = 0; i < 3; ++i) {
|
|
const float axisLen = aabb.max[i] - aabb.min[i];
|
|
if (axisLen > longAxisLen) {
|
|
longAxisLen = axisLen;
|
|
longAxis = i;
|
|
}
|
|
}
|
|
|
|
// split indices list
|
|
const size_t k = indicesList.size() / 2;
|
|
// std::nth_element(indicesList.begin(), indicesList.begin() + k - 1, indicesList.end(),
|
|
// [&](const size_t &a, const size_t &b) {
|
|
// return faceCenters[a][longAxis] < faceCenters[b][longAxis];
|
|
// });
|
|
nth(indicesList, k - 1, longAxis);
|
|
std::vector<size_t> leftIndices(indicesList.begin(), indicesList.begin() + k);
|
|
std::vector<size_t> rightIndices(indicesList.begin() + k, indicesList.end());
|
|
|
|
const AABB leftAABB = computeAABB(leftIndices);
|
|
const AABB rightAABB = computeAABB(rightIndices);
|
|
const size_t leftIdx = dfsBuild(leftIndices, leftAABB, nowIdx);
|
|
const size_t rightIdx = dfsBuild(rightIndices, rightAABB, nowIdx);
|
|
// nodes[nodeIdx] = {leftIdx, rightIdx, 0, aabb};
|
|
nodes[nodeIdx] = BVHNode(leftIdx, rightIdx, 0, aabb);//VS2008
|
|
nodes[leftIdx].parent = nodeIdx;
|
|
nodes[rightIdx].parent = nodeIdx;
|
|
return nodeIdx;
|
|
}
|
|
|
|
bool intersectWithLineSegment(const LineSegment &lineSegment) const {
|
|
return recursiveLineSegIntersection(lineSegment, 0);
|
|
}
|
|
|
|
//private:
|
|
// AABB computeAABB(const std::vector<size_t> &indices) {
|
|
// AABB aabb;
|
|
// for (const size_t &idx: indices) {
|
|
// const Vec3u &face = mesh.indices[idx];
|
|
// for (int i = 0; i < 3; ++i) {
|
|
// const Vec3f &vertex = mesh.vertices[face[i]];
|
|
// for (int j = 0; j < 3; ++j) {
|
|
// aabb.min[j] = std::min(aabb.min[j], vertex[j]);
|
|
// aabb.max[j] = std::max(aabb.max[j], vertex[j]);
|
|
// }
|
|
// }
|
|
// }
|
|
// return {aabb.min, aabb.max};
|
|
// }
|
|
private:
|
|
AABB computeAABB(const std::vector<size_t> &indices) {
|
|
AABB aabb;
|
|
for (std::vector<size_t>::const_iterator it = indices.begin();it!=indices.end();++it) {
|
|
const Vec3u &face = mesh.indices[*it];
|
|
for (int i = 0; i < 3; ++i) {
|
|
const Vec3f &vertex = mesh.vertices[face[i]];
|
|
for (int j = 0; j < 3; ++j) {
|
|
aabb.min[j] = min(aabb.min[j], vertex[j]);
|
|
aabb.max[j] = max(aabb.max[j], vertex[j]);
|
|
}
|
|
}
|
|
}
|
|
return aabb;
|
|
}
|
|
|
|
bool recursiveLineSegIntersection(const LineSegment &lineSegment, size_t nodeIdx) const {
|
|
// segment-box intersection test
|
|
const AABB &aabb = nodes[nodeIdx].boundingBox;
|
|
const Vec3f &dir = lineSegment.getDir();
|
|
bool hit = false;
|
|
for (int i = 0; !hit && i < 3; ++i) {
|
|
float t_min = (aabb.min[i] - lineSegment.start[i]) / dir[i];
|
|
float t_max = (aabb.max[i] - lineSegment.start[i]) / dir[i];
|
|
if (t_min > t_max) {
|
|
std::swap(t_min, t_max);
|
|
}
|
|
if (t_min > lineSegment.getLength() || t_max < 0) return false;
|
|
Vec3f hitPt = lineSegment.start + dir * t_min;
|
|
int otherPlane1 = (i + 1) % 3, otherPlane2 = (i + 2) % 3;
|
|
if (hitPt[otherPlane1] >= aabb.min[otherPlane1] && hitPt[otherPlane1] <= aabb.max[otherPlane1] &&
|
|
hitPt[otherPlane2] >= aabb.min[otherPlane2] && hitPt[otherPlane2] <= aabb.max[otherPlane2]) {
|
|
hit = true;
|
|
}
|
|
}
|
|
if (hit) {
|
|
if (nodes[nodeIdx].left == 0) {
|
|
// leaf
|
|
Vec3u face = mesh.indices[nodes[nodeIdx].right];
|
|
TriangleSegmentIntersectRes res = triangleSegmentIntersection(lineSegment, mesh.vertices[face[0]], mesh.vertices[face[1]],
|
|
mesh.vertices[face[2]]);
|
|
if (!res.hit || res.t < 0 || res.t > lineSegment.getLength()) return false;
|
|
return true;
|
|
} else {
|
|
// check children
|
|
return recursiveLineSegIntersection(lineSegment, nodes[nodeIdx].left) ||
|
|
recursiveLineSegIntersection(lineSegment, nodes[nodeIdx].right);
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// implement nth, without std::nth_element
|
|
// kth is 0-based
|
|
void nth(std::vector<size_t> &indicesList, size_t kth, int longAxis) {
|
|
recursiveChoose(indicesList, 0, indicesList.size() - 1, kth, longAxis);
|
|
}
|
|
void recursiveChoose(std::vector<size_t> &indicesList, size_t begin, size_t end, size_t kth, int longAxis) {
|
|
if (begin >= end) return;
|
|
int i = begin, j = end;
|
|
while (i < j) {
|
|
while (i < j && faceCenters[indicesList[j]][longAxis] >= faceCenters[indicesList[begin]][longAxis]) j--;
|
|
while (i < j && faceCenters[indicesList[i]][longAxis] <= faceCenters[indicesList[begin]][longAxis]) i++;
|
|
std::swap(indicesList[i], indicesList[j]);
|
|
}
|
|
std::swap(indicesList[begin], indicesList[i]);
|
|
if (i == kth) return;
|
|
if (i < kth) recursiveChoose(indicesList, i + 1, end, kth, longAxis);
|
|
else recursiveChoose(indicesList, begin, i - 1, kth, longAxis);
|
|
}
|
|
};
|