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#include "raytracer/raytracer.h"
#include "bvh.h"
bvh::bvh(
const std::vector<KdShape>& p_shapes,
int p_dimension)
{
dimension = p_dimension;
if (p_shapes.empty()) {
return;
}
// compute the new bouding ragion from the shapes and add shapes to the root
BoundingRegion tmp {
glm::vec4(-FINF, -FINF, -FINF, 1.f),
glm::vec4(FINF, FINF, FINF, 1.f),
glm::vec4(-FINF, -FINF, -FINF, 1.f),
glm::vec4(FINF, FINF, FINF, 1.f),
glm::vec4(-FINF, -FINF, -FINF, 1.f),
glm::vec4(FINF, FINF, FINF, 1.f),
glm::vec4(0.f, 0.f, 0.f, 1.f)
};
shapes = std::vector<KdShape>();
for (const auto& shape : p_shapes) {
tmp.xmax = glm::max(tmp.xmax, shape.region.xmax);
tmp.xmin = glm::min(tmp.xmin, shape.region.xmin);
tmp.ymax = glm::max(tmp.ymax, shape.region.ymax);
tmp.ymin = glm::min(tmp.ymin, shape.region.ymin);
tmp.zmax = glm::max(tmp.zmax, shape.region.zmax);
tmp.zmin = glm::min(tmp.zmin, shape.region.zmin);
tmp.center.x = (tmp.xmax.x + tmp.xmin.x) / 2.f;
tmp.center.y = (tmp.ymax.y + tmp.ymin.y) / 2.f;
tmp.center.z = (tmp.zmax.z + tmp.zmin.z) / 2.f;
shapes.push_back(shape);
}
region = tmp;
// split the shapes into two groups, if more than two shapes
if (shapes.size() <= 2) {
return;
}
std::vector<KdShape> leftShapes;
std::vector<KdShape> rightShapes;
for (const auto& shape : shapes) {
if (shape.region.center[dimension] < region.center[dimension]) {
leftShapes.push_back(shape);
}
else if (shape.region.center[dimension] > region.center[dimension]) {
rightShapes.push_back(shape);
} else {
if (leftShapes.size() < rightShapes.size()) {
leftShapes.push_back(shape);
} else {
rightShapes.push_back(shape);
}
}
}
// make the children
leftChild = new bvh(leftShapes, (dimension + 1) % 3);
rightChild = new bvh(rightShapes, (dimension + 1) % 3);
}
float intersectRegion(
glm::vec4 p,
glm::vec4 d,
BoundingRegion region)
{
float tXmin = (region.xmin.x - p.x) / d.x;
float tXmax = (region.xmax.x - p.x) / d.x;
float tYmin = (region.ymin.y - p.y) / d.y;
float tYmax = (region.ymax.y - p.y) / d.y;
float tZmin = (region.zmin.z - p.z) / d.z;
float tZmax = (region.zmax.z - p.z) / d.z;
float tMin = std::max(std::max(std::min(tXmin, tXmax), std::min(tYmin, tYmax)), std::min(tZmin, tZmax));
float tMax = std::min(std::min(std::max(tXmin, tXmax), std::max(tYmin, tYmax)), std::max(tZmin, tZmax));
if (tMin > tMax) {
return FINF;
}
return tMin;
}
void updateAfterCollision(RenderShapeData& objA, RenderShapeData& objB) {
glm::vec3 vA_prime = ((objA.mass - objB.mass) * objA.velocity + 2 * objB.mass * objB.velocity) / (objA.mass + objB.mass);
glm::vec3 vB_prime = ((objB.mass - objA.mass) * objB.velocity + 2 * objA.mass * objA.velocity) / (objA.mass + objB.mass);
objA.velocity = glm::vec4(vA_prime, 0.f);
objB.velocity = glm::vec4(vB_prime, 0.f);
objA.position += objA.velocity;
objB.position += objB.velocity;
}
float RayTracer::traverseBVH(
glm::vec4 p,
glm::vec4 d,
RenderShapeData &testShape,
bvh *root)
{
std::vector<bvh*> stack = std::vector<bvh*>();
stack.push_back(root);
float minT = FINF;
while (!stack.empty())
{
auto current = *stack.back();
stack.pop_back();
if (current.leftChild == nullptr && current.rightChild == nullptr) {
for (const auto &shape: current.shapes) {
glm::vec4 pObject = shape.shape.inverseCTM * p;
glm::vec4 dObject = glm::normalize(shape.shape.inverseCTM * d);
glm::vec4 intersection = findIntersection(pObject, dObject, shape.shape);
if (intersection.w == 0.f) {
continue;
}
intersection = shape.shape.ctm * intersection;
// check within bounds
float tWorld = (intersection.x - p.x) / d.x;
if (tWorld < minT)
{
minT = tWorld;
testShape = shape.shape;
}
}
} else {
float leftIntersect = intersectRegion(p, d, current.leftChild->region);
float rightIntersect = intersectRegion(p, d, current.rightChild->region);
if (leftIntersect != FINF && rightIntersect != FINF) {
if (leftIntersect < rightIntersect) {
stack.push_back(current.rightChild);
stack.push_back(current.leftChild);
} else {
stack.push_back(current.leftChild);
stack.push_back(current.rightChild);
}
} else if (leftIntersect != FINF) {
stack.push_back(current.leftChild);
} else if (rightIntersect != FINF) {
stack.push_back(current.rightChild);
}
}
}
return minT;
}
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