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#include "kdtree.h"
#include "raytracer/raytracer.h"
// Constructor
KdTree::KdTree(int pDimension, float pSplitCoord) {
empty = true;
dimension = pDimension;
splitCoord = pSplitCoord;
shapesWithinBounds = std::vector<KdShape>();
leftChild = nullptr;
rightChild = nullptr;
}
void KdTree::insert(KdShape shape)
{
// first, add shape to this node
shapesWithinBounds.push_back(shape);
if (empty) {
empty = false;
return;
}
int nextDimension = (dimension + 1) % 3;
if (dimension == 0) // x split
{
if (
shape.region.xmin.x > splitCoord
)
// bound box is strictly to the right, only add right
{
if (rightChild == nullptr) {
rightChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is y
}
}
else if (
shape.region.xmin.x < splitCoord
&& shape.region.xmax.x > splitCoord
)
// bounding box overlaps center, need to add to both children
{
if (rightChild == nullptr) {
rightChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is y
}
if (leftChild == nullptr) {
leftChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is y
}
}
else if (
shape.region.xmax.x < splitCoord
)
// bounding box strictly to the left, only add left
{
if (leftChild == nullptr) {
leftChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is y
}
}
}
else if (dimension == 1) // y split
{
if (shape.region.ymin.y > splitCoord) {
if (rightChild == nullptr) {
rightChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is z
}
}
else if (
shape.region.ymin.y < splitCoord
&& shape.region.ymax.y > splitCoord
) {
if (rightChild == nullptr) {
rightChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is z
}
if (leftChild == nullptr) {
leftChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is z
}
}
else if (
shape.region.ymax.y < splitCoord
) {
if (leftChild == nullptr) {
leftChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is z
}
}
}
else if (dimension == 2) // z split
{
if (shape.region.zmin.z > splitCoord) {
if (rightChild == nullptr) {
rightChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is x
}
}
else if (
shape.region.zmin.z < splitCoord
&& shape.region.zmax.z > splitCoord
) {
if (rightChild == nullptr) {
rightChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is x
}
if (leftChild == nullptr) {
leftChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is x
}
}
else if (
shape.region.zmax.z < splitCoord
) {
if (leftChild == nullptr) {
leftChild = new KdTree(
nextDimension,
shape.region.center[nextDimension]); // next dim is x
}
}
}
// now, add shape to children
if (leftChild != nullptr) {
leftChild->insert(shape);
}
if (rightChild != nullptr) {
rightChild->insert(shape);
}
}
BoundingRegion KdTree::transformBoundingRegion(BoundingRegion region, glm::mat4 transformationMatrix, glm::vec3 basis)
{
std::vector<glm::vec4> transformedPoints = std::vector<glm::vec4>();
transformedPoints.push_back(transformationMatrix * region.xmax);
transformedPoints.push_back(transformationMatrix * region.xmin);
transformedPoints.push_back(transformationMatrix * region.ymax);
transformedPoints.push_back(transformationMatrix * region.ymin);
transformedPoints.push_back(transformationMatrix * region.zmax);
transformedPoints.push_back(transformationMatrix * region.zmin);
BoundingRegion transformedRegion{
glm::vec4(-FINF),
glm::vec4(FINF),
glm::vec4(-FINF),
glm::vec4(FINF),
glm::vec4(-FINF),
glm::vec4(FINF),
glm::vec4(0.f)
}; // just init values, will be set to be correct
// these are the new bound points, but they may have been rotated or reflected
// this also ensures axis aligned bounding boxes, given the dots with the basis
for (glm::vec4 point: transformedPoints) {
if (point.x * basis.x > transformedRegion.xmax.x) {
transformedRegion.xmax = point;
}
if (point.x * basis.x < transformedRegion.xmin.x) {
transformedRegion.xmin = point;
}
if (point.y * basis.y > transformedRegion.ymax.y) {
transformedRegion.ymax = point;
}
if (point.y * basis.y < transformedRegion.ymin.y) {
transformedRegion.ymin = point;
}
if (point.z * basis.z > transformedRegion.zmax.z) {
transformedRegion.zmax = point;
}
if (point.z * basis.z < transformedRegion.zmin.z) {
transformedRegion.zmin = point;
}
}
transformedRegion.center = transformationMatrix * region.center;
return transformedRegion;
}
// TODO: return the float with the shape
float RayTracer::traverse(
glm::vec4 p,
glm::vec4 d,
float tStart,
float tEnd,
RenderShapeData &testShape,
KdTree *tree)
{
if (tree == nullptr) {
return FINF;
}
// leaf node
if ( tree->shapesWithinBounds.size() <= 2 ||
tree->leftChild == nullptr || tree->rightChild == nullptr)
{
float minT = FINF;
for (const auto &shape: tree->shapesWithinBounds) {
glm::vec4 pObject = shape.shape.inverseCTM * p;
glm::vec4 dObject = glm::normalize(shape.shape.inverseCTM * d);
bool isHit = false;
glm::vec4 intersection = findIntersection(pObject, dObject, shape.shape, isHit);
if (intersection.w == 0.f) {
continue;
}
intersection = shape.shape.ctm * intersection;
// check within bounds
if (
intersection.x <= shape.region.xmax.x && intersection.x >= shape.region.xmin.x
&&
intersection.y <= shape.region.ymax.y && intersection.y >= shape.region.ymin.y
&&
intersection.z <= shape.region.zmax.z && intersection.z >= shape.region.zmin.z
)
{
float tWorld = (intersection.x - p.x) / d.x;
if (tWorld < minT) {
minT = tWorld;
testShape = shape.shape;
}
}
}
return minT;
}
// solve for t, only in current 1d-dimension
float t = (tree->splitCoord - p[tree->dimension]) / d[tree->dimension];
// There are three cases:
// 1) only intersects with left (front) child (t <= tEnd)
// 2) only intersects with right (back) child (t <= tStart)
// 3) intersects with both children (tStart <= t <= tEnd)
// on last case, we need to traverse both children,
// but gain a significant speedup by traversing the one that is closer first.
if (t <= tStart && tree->rightChild != nullptr) // case 1)
{
return traverse(p, d, tStart, tEnd, testShape, tree->rightChild);
}
else if (t >= tEnd && tree->leftChild != nullptr) // case 2)
{
return traverse(p, d, tStart, tEnd, testShape, tree->leftChild);
}
else // case 3)
{
float t_hit = traverse(p, d, tStart, t, testShape, tree->leftChild);
if (t_hit < t)
{ // this is where we save time!
return t_hit;
}
return traverse(p, d, t, tEnd, testShape, tree->rightChild);
}
}
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