bvh | A modern C++ BVH construction and traversal library | Game Engine library

I was working on my ray tracer written in C++ following this series of books: Ray Tracing in One Weekend. I started working a little bit on my own trying to implement features that weren't described in the book, like a BVH tree builder using SAH, transforms, triangles and meshes.

NOTE: The BVH implementation is based on two main resources which are this article: Bounding Volume Hierarchies and C-Ray (A ray tracer written in C).

After I implemented all of that I noticed that there was some weirdness while trying to use some materials on meshes. For example, as the title says, the metal material looks completely black:

In the first image you can see how the metal material should look like and in the second one you can see how it looks like on meshes.

I spent a lot of time trying to figure out what the issue was but I couldn't find it and I couldn't find a way of tracking it.

If you want to take a look at the code for more clarity the ray tracer is on GitHub at https://github.com/ITHackerstein/RayTracer. The branch on which I'm implementing meshes is meshes.

To replicate my build environment I suggest you follow this build instructions:

$ git clone https://github.com/ITHackerstein/RayTracer

$ cd RayTracer

$ git checkout meshes

$ mkdir build

$ cd build

$ cmake ..

$ make

$ mkdir tests

At this point you're almost ready to go except you need the TOML scene file an the OBJ file I'm using which are these two:

• boh.toml (Scene file)
• teapot.obj (Teapot OBJ file)

Download them and place them in the build/tests and after that make sure you are in the build folder and run it using the following command:

$ ./RayTracer tests/boh.toml

After it finishes running you should have a tests/boh.ppm file which is the resulting image file stored using PPM format. If you don't have a software that let's you open it there are multiple viewers online.

NOTE: My platform is Linux, I didn't test it on Windows or Mac OS.

EDIT

Does the mesh work with other materials?

So as you can in the first image and especially in the second one we have we have some darker rectangular spots, and also the lighting seems kinda messed up. In the third image you have an idea of how it works on a normal primitive.

I'm writing a path tracer as a programming exercise. Yesterday I finally decided to implement multithreading - and it worked well. However, once I wrapped the test code I wrote inside main() in a separate renderer class, I noticed a significant and consistent performance drop. In short - it would seem that filling std::vector anywhere outside of main() causes threads using its elements to perform worse. I managed to isolate and reproduce the issue with simplified code, but unfortunately I still don't know why it happens or what to do in order to fix it.

Performance drop is quite visible and consistent:

I am creating an OpenGL based ray tracer for polygon models. The basic structure is about to render the results to a quad from the fragment shader. To accelerate the application, BVH-trees are used.

The problem is, that the method, which tests, if the shadow ray intersects something returns true where it should not return true, meaning that, there is no shadows at all. Only two side of the cube are black, they are not facing the light source.

Here is a screenshot, where you can see a cube on a plane. And there is a light source as well.

Here is the useful parts from the fragment shader: the trace and the shadowIntersect method:

I am creating an OpenGL based ray tracer for polygon models. The basic structure is about to render the results to a quad from the fragment shader. To accelerate the application, BVH-trees are used. Because there is no recursion in GLSL, I decided to find an other way to traverse the bounding boxes. The bvh nodes (including the boxes) and the primitive coordinates are sent to the fragment shader into a shader storage buffer.

I am using the basic idea described in: Threaded BVH-tree traversal in shaders

The above solution uses links "which are used to skip nodes which don't need to be evaluated". There is a hit link: which node to jump to in case of a hit and there is a miss link: which node to jump to in case of a miss.

Actually, I am not using links to navigate between the boxes, as I have a complete binary tree, which makes easier to navigate between the different depths. But the basic concept is similar to link above. I store the nodes in breadth-first order.

Unfortunately, when the program is running there is a weird result. I can see the object partly ray-traced and the bounding box as well. The bounding box has grey color, but this color should be the color of the background.

The below picture shows the current state. You should see a cone in a grey background, but instead of this you can see a grey bounding box around its object.

... and how it should look like (it is a non bvh-tree version)

Here is my fragment shader:

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I have a JSON array which has multiple records which is

I am working on an opengl based raytracer application in c++. I would like to send data from the cpu side to the fragment shader. The data is a bounding volume hierarchies (BVH) tree. Unfortunately on the shader side I got junk data, when I am trying to write out the coordinates as color with gl_fragcolor. I don't know why. Any help is appreciated.

I have this structure on CPU side:

About the project:

I am working on an Opengl ray-tracer, which is capable of loading obj files and ray-trace it. My application loads the obj file with assimp and then sends all of the triangle faces (the vertices and the indices) to the fragment shader by using shader storage objects. The basic structure is about to render the results to a quad from the fragment shader.

When I load bigger obj-s (more than 100 triangles), it took so much time for the computer to do the intersections, so I started creating a BVH-tree to speed up the process. My BVH splits up the space into two axis-aligned-bounding-boxes recursively based on the average median of the triangles faces contained in the AABB.

I succeed to build the BVH tree structure (on CPU) and now I want to convert it to a simple array, then send it to fragment shader (to a shader storage buffer).

Here is the method responsible for converting the BVH root node into an array:

I am working on an Opengl ray-tracer, which is capable of loading obj files and ray-trace it. My application loads the obj file with assimp and then sends all of the triangle faces (the vertices and the indices) to the fragment shader by using shader storage objects. The basic structure is about to render the results to a quad from the fragment shader.

When I load bigger obj-s (more than 100 triangles), it took so much time for the computer to do the intersections, so I started creating a BVH-tree to speed up the process. My BVH splits up the space into two axis-aligned-bounding-boxes recursively based on the average median of the triangles faces contained in the AABB.

I succeed to build the BVH tree structure (on CPU) and now I want to convert it to a simple array, then send it to fragment shader (to a shader storage buffer).

This is the structure of my BVH class.