Blender Mesh Import issue

Hey, I have been using Blender and the new Unity 3. My issue occurs when importing the mesh into the Game engine. While the mesh is whole in the blender, certain faces are missing when it is imported into unity. I tried exporting it as a .fbx file, to no avail. If any other blender user has a solution to the problem, please respond.

Try selecting the whole mesh (A Key) and switching to Edit mode. Then click "Mesh" and go to "Normals", then click "Recalculate Normals Outside"

Usually what you describe is the result of some normals on the model facing inwards. Blender sometimes makes it hard to see this (there is a button for "Show Normals" in a submenu in the edit mode). If you Show Normals, you can examine the normals in the blank spaces and Flip (under Mesh/Normals/Flip) them outward.

You may try this:

BLENDER (2.49b):

  1. if your model is “closed” (like a box or character) disabled DOUBLE SIDED, if not leave it enabled

  2. Make sure there are no lighting or cameras (if there are, erease them all)

  3. In edit mode select your model by pressing “A” key

  4. Press “W” key and in the pop up menu select “REMOVE DOUBLES” and accept.

  5. Press Ctrl + N to calculate normals

  6. Save it as a normal .blend file (Unity imports it automatically) pressing Ctrl + W.

Suggestions:

* The most stable version of blender is 2.49b
* Save your .blend files in your Project/Assets/Anyfolder so unity imports it inmmediatly after you saved your file.
* Don't use particles, bakes or cloth simulations from blender.
* You can RECALCULATE NORMALS only in the vertices that are wrong (that means not always is needed to select ALL vertices)

Hope it helped

I’ve have just encountered the problem myself all i did was press A in object mode switch to edit mode click on mesh click on normal’s and press flip normal’s huh so many models deleted because of this error when it was such an easy fix

hello, i always am using blender to make a quick yet good creation for my game, and i notice that problem often. i find that if i find out which face it is, and just play with it, i make new faces, delete overlapping faces, etc. basically, i don't have a solution, but until someone does, you could do what i do: manually fix it.

I actually found that you don’t flip the normals outside, you just flip the normals of the faces that are facing in. I have no idea why Blender does this, but it just does.

I actually found that you don’t flip the normals outside, you just flip the normals of the faces that are facing in. I have no idea why Blender does this, but it just does.

Two years later, I’ve encountered the exact same issue, so to those wandering through:

Forget FBX, use COLLADA.

The only correct way to deal with this is to apply transform modification within Blender, to do this select your object and then use ctrl+A, then choose rotation and scale. This will save the current state of the transform as the default. This will also show you faces that may be inverted because of a negative scale.

My problem was that my missing faces material was set to transparent. It was not transparent for me in Blender but in Unity it was not visible.

Lots of misinformation here. I know this is old, but it came up when I was looking for something else so maybe someone will find it useful.

All triangles / polygons on your mesh have a normal orientation which shows which side is facing ‘out’ and will be drawn in the engine.

The other side will not be drawn unless you use a material / shader that forces it on - this is not recommended for normal meshes since it’s unnecessary and wasteful.

Blender by default does not show the normal orientation (no idea why, this is standard in all other 3D apps).

Step 1: Identify Problem Faces

Go to Viewport Overlays and turn on Face Orientation. Your mesh will now be drawn in blue for faces facing the camera and red for those that do not.

Step 2: Fixing Problem Faces

Select any faces that are red (when you are looking at it from where you will be in game) and press Alt-N, then select the option to flip those Normals. Those faces will now be blue in Blender and show up in game.

Step 3: Making Material Cull Backfaces

A slightly more complex way of doing this, which is easier long term, is to make the material not draw faces which are facing the wrong way, as the engine doesn’t.

The forum doesn’t allow a third image in a single reply :stuck_out_tongue:

And is blocking me from adding it as a comment.

  1. Select your mesh.
  2. Go to Materials tab (bottom right pane in default Blender Layout)
  3. Go to Setting sub-tab and open it up.
  4. Enable backface culling for the material that is applied to the mesh.
  5. Faces with the wrong orientation will not be drawn.