- fixed: P_Recalculate3DFloors may not be called before the vertex buffer has been set up.

Since this function creates dynamic copies for 3D floors that need to be split it requires the vertex buffer index to be set up.
In older versions this did not produce errors because there was a fallback render path that was less efficient.
Now with that fallback removed this resulted in temporary 3D floors being created without valid vertex data.

src/p_3dfloors.cpp

@@ -891,11 +891,6 @@ void P_Spawn3DFloors (void)
 		line.special=0;
 		line.args[0] = line.args[1] = line.args[2] = line.args[3] = line.args[4] = 0;
 	}
-	// kg3D - do it in software
-	for (auto &sec : level.sectors)
-	{
-		P_Recalculate3DFloors(&sec);
-	}
 }