Complete 

Bret Ware and Regan Ware from Item_42, the developer of BLISTER, have published a complete tutorial on building arms and animating them for an FPS game with the help of 3ds Max and Unreal Engine 4. You will learn one way of creating a pair of first person shooter arms that are fully rigged, suitable for UE4 and easy to animate and a way of exporting the arm rig, weapons and associated animations to UE4 for use within an FPS game.

RIGGING THE ARMS IN 3DS MAX

I – Lowpoly mesh preparation

The first thing to think about is what neutral pose the arms will be in. You can either create them in a straight neutral pose which is easier for the rigger but harder for the sculptor, or you can create them in a pose that fits the position they’re most likely to spend the most time in. I went for the latter. Just note that it’s harder to accurately rig a pre-posed arm.

When you create the lowpoly for your FPS arms rig, you should double-chamfer knuckles and other areas that will be prone to large angle movements. You can blend these double-chamfered polygons between adjacent bones later with minimal UV stretching.

Before you begin rigging the arm, ensure that you’ve created the UV map and textures for the lowpoly as you normally would. The diffuse texture will be very useful in 3DS Max when looking out for UV stretching. UV stretching happens when a bone is given too much weighting on a particular face or set of vertices on the lowpoly. You want to avoid this as much as possible for a good rig.

II – Creating a custom skeleton in 3DS Max for FPS arms

1. Make sure your arms are centred at 0,0,0. There is a cheap way to do this. First, make sure all elements of your arm mesh are within the same object. 

2. move to the Hierarchy tab on the right-side panel. 

3. Select Affect Pivot Only under Adjust Pivot and under Alignment, select Center to Object.

4. Deselect Affect Pivot Only and move your rig to 0,0,0

Alternatively, if this moves your arm rig too far backwards from the centre point, move the rig forwards using the transform controls, reselect Affect Pivot Only and centre to zero using the panel in the last image above.

We will begin creating the skeleton. Press ALT+X on the arm mesh to toggle xray mode so that you can see through the mesh.

5. right click and press ‘Freeze Selection’ so that while you’re working you don’t accidentally select the arms. 

6. Go to the Animation panel and select Bone Tools.

7. Make sure you’re in the appropriate viewport. Press T to enter the orthographic Top viewport. Press F4 if you want to see the wireframe view as you work. Toggle the Layer Explorer, pick whether you want to work on the Left or Right arm and create a layer called “bones_left” or “bones_right”. Make sure it’s the active layer by pressing the grey layer icon to turn it blue. Unlike my picture, you will only have one layer right now called “bones_right”, and maybe a separate layer for your frozen mesh. 

8. Enter Bone Edit Mode and press Create Bones. Draw your first bone in the viewport. When you have drawn your first bone the next bone will automatically jump to your mouse position so you can draw the next bone. Create the upper arm, lower arm and wrist/hand. Right click twice to exit Create Bones mode. Delete the Nub bone at the end of the hand bone you just created; it isn’t necessary. 

9. Stay in Bone Edit Mode. Edit the size of the bones with the Fin Adjustment Tools. Change the width, height and taper under Bone Objects to suit the arms you’re working with. Add fins under the Fin panel if you want.