One of the features of the engine that I wanted to implement was collapsing buildings, once a building suffered enough damage, then it would simply fall in upon itself.

You would have seen the start of that work in the previous videos showing the exploding buildings, a spectacular side-effect caused by the physics objects that the building is converted into overlapping, which resulted in the Bullet physics library flinging them violently apart.

The next step towards actual collapsing buildings was to tweak the object bounding boxes so as not to overlap. I was planning to do this today, however I slowed the physics speed right down and noticed that wall pieces that break up into multiple objects were actually starting those objects in slightly the wrong location, exacerbating the explosion problem.

It took a while to figure out a way to position them correctly, but once I had fixed it, I found that it drastically reduced the exploding problem.

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I still need to fix the bounding box issue as the multi-story building still explodes and the occasional roof piece shoots for the moon, but it's mostly working now.

Here's a final exploding building video for the road...

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