Titan benchmark

Yesterday I had the chance to run the raycaster on an NVidia TITAN.
The result for the tree-scene was
140 fps, 1920x1080
200-300 fps, 1280x720

Parallel all permutations - non-recursive - GPU optimal

This post is a general one - not voxel related.

Some time ago I developed a a simple, fast and yet non-recursive method to directly compute the n'th permutation. Thats useful especially when working on the graphics card with CUDA for parallel evaluations. (it might have been published somewhere already - so if you know the reference, you can post it as a comment)

The algorithm is based on the following property. Lets say there are 6 characters in the string to permute. Then the result is 6! = 720 combinations. In the first column of the results, we get 720/6=120 lines of each character. This means if the index counts from 0 to 719, then the first character to be removed is computed as remove_index = index/120.

For the next column, 5 numbers are left. This means, that 120 = 5 * 24 lines of the same character - and so on. 

We the following list of removes:
column0: remove_index = (a/120)%5;
column1: remove_index = (a/24)%4;
column2: remove_index = (a/6)%3;
column3: remove_index = (a/2)%2;
column4: remove_index = (a/1)%1;

Code snipplet:

std::string default = "12345";
int perm=1, digits=default.size();
for (int i=1;i<=digits;perm*=i++);
for (int a=0;a<perm;a++)
{
std::string avail=default;
for (int b=digits,div=perm;b>0; b--)
{
div/=b;
int index = (a/div)%b;
printf("%c", avail[index] );
//avail[index]=avail[b-1]; // non-lexigraphic but fast
avail.erase(index,1) ; // lexigraphically correct
}
printf("\n");
}
printf("permutations:%d\n",perm);

In the code, perm defines the Lehmer code (wiki)

Another slight speedup

Further optimization helped to speed up a bit more.

Another speedup: now ~70fps@1920x1024

Seems working on the algorithm pays off. Todays version reaches an even higher performance.
Also better performance for the forest scene as well (960x512@~100fps)

OpenCL Happy Buddha Raycasting 1920x1024@50fps

Here a first glimpse of  a new optimization. The good old Happy Buddha scene (1024^3) raycasted at 50 fps at almost HD resolution (1920x1024). Video below. For 960x512 it renders at 150 fps.

Instancing: Combined AABB + Voxel raycasting

Here a first combined test by raycasting 10.000 to 100.000 models.

Due to the mixed kernel, performance is not as good as pure octree.

Blending two Voxel Scenes

Here a experiment to apply blendshapes to a voxel scene. Its much slower, still runs at interactive framerates (20-30). The video lags as the framecapture@1024x768 took quite a lot of CPU time.