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BVH: implicit copy of source and sort in place
- Removed the const qualifier for the `objects` vector in the BVH constructor arguments. This makes an implicit (hence modifiable) copy in the un-indexed constructor. This should be ok though because we don't need the scene objects array after the BVH has been built. - Because the indexed constructor is now non-const, the object sorting now happens in place, without requiring the construction of a new copy of the subsection in question. - Removed the second unnecessary branch within condition "object_span == 2" per issue #1327. - Added Markus Boos to credits. Resolves #1327 Resolves #1388
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-43
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5 files changed

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-43
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‎CHANGELOG.md‎

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@@ -29,6 +29,8 @@ then.
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- Change - Reworked the AABB chapter (#1236)
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- New - add section on alternative 2D primitives such as triangle, ellipse and annulus (#1204,
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#1205)
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- Change - changed bvh construction (removed const qualifer for objects vector) so sorting is done
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in place and copying of vector is avoided, better bvh build performance (#1388, #1391)
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### The Rest of Your Life
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‎books/RayTracingTheNextWeek.html‎

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class bvh_node : public hittable {
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public:
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bvh_node(const hittable_list& list) : bvh_node(list.objects, 0, list.objects.size()) {}
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bvh_node(hittable_list list) : bvh_node(list.objects, 0, list.objects.size()) {}
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bvh_node(const std::vector<shared_ptr<hittable>>& src_objects, size_t start, size_t end) {
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bvh_node(std::vector<shared_ptr<hittable>>& objects, size_t start, size_t end) {
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// To be implemented later.
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}
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class bvh_node : public hittable {
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public:
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...
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bvh_node(const std::vector<shared_ptr<hittable>>& src_objects, size_t start, size_t end) {
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bvh_node(std::vector<shared_ptr<hittable>>& objects, size_t start, size_t end) {
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int axis = random_int(0,2);
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auto comparator = (axis == 0) ? box_x_compare
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: (axis == 1) ? box_y_compare
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: box_z_compare;
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auto objects = src_objects; // A modifiable array of the source scene objects
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size_t object_span = end - start;
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if (object_span == 1) {
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left = right = objects[start];
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} else if (object_span == 2) {
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if (comparator(objects[start], objects[start+1])) {
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left = objects[start];
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right = objects[start+1];
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} else {
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left = objects[start+1];
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right = objects[start];
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}
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left = objects[start];
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right = objects[start+1];
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} else {
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std::sort(objects.begin() + start, objects.begin() + end, comparator);
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class bvh_node : public hittable {
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public:
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...
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bvh_node(const std::vector<shared_ptr<hittable>>& src_objects, size_t start, size_t end) {
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bvh_node(std::vector<shared_ptr<hittable>>& objects, size_t start, size_t end) {
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++ highlight
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// Build the bounding box of the span of source objects.
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bbox = aabb::empty;
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for (int object_index=start; object_index < end; object_index++)
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bbox = aabb(bbox, src_objects[object_index]->bounding_box());
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for (size_t object_index=start; object_index < end; object_index++)
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bbox = aabb(bbox, objects[object_index]->bounding_box());
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
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...
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class bvh_node : public hittable {
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public:
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...
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bvh_node(const std::vector<shared_ptr<hittable>>& src_objects, size_t start, size_t end) {
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bvh_node(std::vector<shared_ptr<hittable>>& objects, size_t start, size_t end) {
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// Build the bounding box of the span of source objects.
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bbox = aabb::empty;
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for (int object_index=start; object_index < end; object_index++)
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bbox = aabb(bbox, src_objects[object_index]->bounding_box());
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for (size_t object_index=start; object_index < end; object_index++)
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bbox = aabb(bbox, objects[object_index]->bounding_box());
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++ highlight

‎books/acknowledgments.md.html‎

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- [Manas Kale](https://github.com/manas96)
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- Marcus Ottosson
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- [Mark Craig](https://github.com/mrmcsoftware)
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- Markus Boos
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- Matthew Heimlich
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- Nakata Daisuke
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- [Nate Rupsis](https://github.com/rupsis)

‎src/TheNextWeek/bvh.h‎

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class bvh_node : public hittable {
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public:
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bvh_node(const hittable_list& list) : bvh_node(list.objects, 0, list.objects.size()) {}
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bvh_node(hittable_list list) : bvh_node(list.objects, 0, list.objects.size()) {}
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bvh_node(const std::vector<shared_ptr<hittable>>& src_objects, size_t start, size_t end) {
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bvh_node(std::vector<shared_ptr<hittable>>& objects, size_t start, size_t end) {
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// Build the bounding box of the span of source objects.
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bbox = aabb::empty;
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for (size_t object_index=start; object_index < end; object_index++)
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bbox = aabb(bbox, src_objects[object_index]->bounding_box());
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bbox = aabb(bbox, objects[object_index]->bounding_box());
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int axis = bbox.longest_axis();
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auto comparator = (axis == 0) ? box_x_compare
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: (axis == 1) ? box_y_compare
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: box_z_compare;
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auto objects = src_objects; // A modifiable array of the source scene objects
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size_t object_span = end - start;
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if (object_span == 1) {
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left = right = objects[start];
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} else if (object_span == 2) {
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if (comparator(objects[start], objects[start+1])) {
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left = objects[start];
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right = objects[start+1];
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} else {
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left = objects[start+1];
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right = objects[start];
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}
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left = objects[start];
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right = objects[start+1];
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} else {
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std::sort(objects.begin() + start, objects.begin() + end, comparator);
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‎src/TheRestOfYourLife/bvh.h‎

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class bvh_node : public hittable {
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public:
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bvh_node(const hittable_list& list) : bvh_node(list.objects, 0, list.objects.size()) {}
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bvh_node(hittable_list list) : bvh_node(list.objects, 0, list.objects.size()) {}
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bvh_node(const std::vector<shared_ptr<hittable>>& src_objects, size_t start, size_t end) {
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bvh_node(std::vector<shared_ptr<hittable>>& objects, size_t start, size_t end) {
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// Build the bounding box of the span of source objects.
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bbox = aabb::empty;
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for (int object_index=start; object_index < end; object_index++)
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bbox = aabb(bbox, src_objects[object_index]->bounding_box());
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for (size_t object_index=start; object_index < end; object_index++)
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bbox = aabb(bbox, objects[object_index]->bounding_box());
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int axis = bbox.longest_axis();
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auto comparator = (axis == 0) ? box_x_compare
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: (axis == 1) ? box_y_compare
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: box_z_compare;
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auto objects = src_objects; // A modifiable array of the source scene objects
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size_t object_span = end - start;
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if (object_span == 1) {
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left = right = objects[start];
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} else if (object_span == 2) {
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if (comparator(objects[start], objects[start+1])) {
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left = objects[start];
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right = objects[start+1];
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} else {
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left = objects[start+1];
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right = objects[start];
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}
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left = objects[start];
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right = objects[start+1];
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} else {
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std::sort(objects.begin() + start, objects.begin() + end, comparator);
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