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COLLADA based Skinned Mesh Animation in XNA now working

A few days ago I finished the preliminary COLLADA based Model implementation in XNA which is the foundation of my bachelor thesis. Due to limited time I could only implement the skinning on the CPU side, but hardware skinning will be implemented afterwards, when I’m done with the writing of my thesis.

So I got skinned mesh animation working after a few hours of bug tracing. At some point I read the vertex weights reverted from the vertex stream (WZYX  rather than XYZW) which produced some weird results. Unfortunately I was searching for the bug in the wrong place for most of the time, since I thought I had read the skin information wrongly. But eventually I found the bug as mentioned above in the animator class itself where the weights simply were read in the wrong order.

So, even though there is really nothing special to show, I’m uploading a small video as proof anyway. ^_^ The model I used was already rigged but not animated. That’s why the animation in the video is so bad, in case you wonder.

Anyway, now it works. However, it’s not easy to find free animated models, apparently. For testing purposes I used, among others, again the model from Gears of War. Unfortunately I will probably not be able to use it officially in line with my bachelor thesis due to legal issues (unless I get permission from Epic Games). I spend this morning searching for good freely available and already animated models but had no luck so far.

After my fruitless search I quickly implemented opacity maps, though not very sophisticated. I’m not handling it like it should be handled, i.e. considering the drawing order from back to front etc., but as it is implemented now it will suffice for the most simple use cases. The following screenshot shows a COLLADA  model I downloaded from Google’s 3D Warehouse that was created in SketchUp for Google Earth, which is using opacity maps for fences and statues on the roof:

For the next days I won’t be implementing too many new things, since I’m primarily occupied with writing the actual text of the thesis. This will take hopefully not much longer than the next two weeks.

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