@JoeJ exactly, now I found correct solution

TVertexPT vertices[] = {
   {{-1.0f, -1.0f,  1.0f}, {0.0f, 1.0f}},
   {{ 1.0f, -1.0f,  1.0f}, {1.0f, 1.0f}},
   {{ 1.0f,  1.0f,  1.0f}, {1.0f, 0.0f}},
   {{-1.0f,  1.0f,  1.0f}, {0.0f, 0.0f}…

@snoken Basically what joeJ said. When the changes become small enough, call it good enough and set the amount of rotation such that all vertices are on the same plane.

I originally was thinking i could use this for my robot-shooting game. The robots explode and the legs/arms/body parts fall off. I …

While you're addressing geometry, you aren't addressing anything else.

What about surface normals? What about UV coordinates (and ST coordinates)? What about the effects of assorted shaders being applied?

If all you're looking for is the surface vertex positions those few are fine. But if you're doin…