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Thursday, December 11, 2014

How the voxel zebra got its stripes

Here is the story behind these two zebras:

The zebra at the left was handcrafted by an artist. It is a traditional polygon mesh where each triangle has UV coordinates. These coordinates are used to wrap a handpainted 2D texture over the triangle mesh.

This is how most 3D objects have been created since the beginning of time. It is a very powerful way to capture rich surfaces in models. It is very efficient, it aligns well with the hardware, allows you to have incredible detail and even animate.

Voxels can also have UV. This allows you to capture more detail at much lower voxel resolution.

The zebra at the right had an interesting life. It went from the artist made polygon into a full voxel representation. Then it went back to triangles just before rendering. UV coordinates were preserved along this trip, but there is a lot of trickery involved. These are different meshes.

Both models use exactly the same texture the artist made. This is the important part. You could draw both in the same draw call.

The voxel version has fewer triangles. This is a 100x100x100 voxelization. To give you an idea of how small that is, here is the equivalent of that in 2D:
If you approached the zebra and looked at its head, at the left is how big these voxels would be:

At the right you see our results. The same amount of voxels can provide a lot more detail if UV coordinates are used.

I am happy with the results. To me this is as important as solving the physics problem. This will take the look of voxel scenes to a whole new level, while allowing you to harvest and destroy these carefully designed things.

This is still experimental and there are tricky issues ahead, like handling topology changes (holes closing.) and dealing with aliasing. For now I got to make a post with images of only zebras in it.

Monday, December 1, 2014

Looking inside voxel assets

You do not have to be a cat or a Floyd fan to enjoy a laser show.

Here is a laser-looking tool that allows you to explore the inside of voxelized assets. The challenge was to show the interior features of a model while keeping the context clear in the viewer's mind. The following video shows it in action:

I really like this new toy. I have wasted many hours already playing with it, looking if any of the assets we have so far had any sort of defects inside, getting a better understand of how these models are built.

It also allows to place pivot points inside our instances:

This is how we came up with it. We could not see anything inside!