Parts of model not appearing in unity 3d

When i export a model that i rig and animated from blender . Parts of the leg don’t appear nicely on unity 3d. For blender , i use weight painting for the amratures . Anyone can tell me whats the solution for this problem . Thanks a lot

Are you sure the Normals are facing the right way? I’ve had that issue with Blender a couple times when I wasn’t paying too much attention.

You can also try moving the base/root of the armature around and make sure everything moves with it.

part of the legs are missing and when i move them in pose mode the model looks deform

You may have applied weight to the wrong vertices? Or the weight is higher on the wrong bone and it is bending improperly. Usually I manually add the verts to vert groups and assign them to bones. Try just having each vert assigned to 1 bone, not like a mixture. I don’t know how to word that much better, sorry. You can also try to parent the mesh to the armature and use the bone heat.