-Add a plane, subdivide it a bit
-Raise or lower some faces until satisfied
Doing this has often led to having some faces not behave like it should, and would cause the player to sink slightly into the ground.
It also made faces change shapes when going in/out of edit mode…
I use an external heightmap generator, such as geomorph, which can do nice stuff such as various types of erosion.
Then I import it and apply it as the displacement modifier.
Finally, the step you’re interested in is:
Apply the decimate modifier with collapse to ~0.95 (you can tweak it and generate LOD) and check … the triangulate button.
I had the same problem a while back. I was able to fix it by triangulating the faces. There are multiple ways of doing this. ctrl+T is an easy way of doing this.
By checking the triangulate button on the decimate modifier, you do triangulate the mesh, so they are equivalent, except that the decimate modifier will also remove any nearly-flat surfaces and join them into a single face.
Be aware, the GPU always creates triangles. You only “save” faces while modelling. This is btw. the source of your problems.
A) you created distorted quads (they are not flat)
B) the renderer and the physics engine triangulate the quads with different results (there are always two exclusive solutions to triangluate a rectangle)
Solution: Avoid distorted quads. If you can’t - excitedly triangulate the distorted quads by yourself.
@Monster: It’d be a little tough to avoid them, when you say “By yourself”, you mean triangulating them manually (via the Knife tool)
or just doing what was mentioned above?