Complete FPS Arms Rig and Animation Tutorial from 3ds Max to UE4

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

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. 

10. Stay in Bone Edit Mode. Enter Perspective Mode by pressing P and adjust the position of the bones so that they fit the arms. Try to keep everything as straight and orderly as possible. Never twist a bone that relies on another bone using the Rotate tool unless you have accounted for the other bones in that rotation. If you do have to rotate a bone, make sure all the other bones have a similar relative transformation. 

11. Stay in Bone Edit Mode. You can sometimes (but not always) align bones by using the Align tool. Select the bone you wish to align to another, press the Align tool and make your selection in the viewport. 

13. Select Create Bones again. Create a hierarchy of finger bones in Bone Edit Mode. This time, keep the Nub bone at the end of the hierarchy. Exit Bone Edit Mode and select all 4 finger bones. Hold SHIFT and drag along an axis. This will produce a copy. Make 3 copies for 4 fingers. 

14. It is very important to make sure the bones do not deviate on their axes. They have to be straight to work effectively. You may have to rotate the finger bone hierarchy to fit them inside the mesh, but make sure you rotate them OUTSIDE Bone Edit Mode so that they stay straight relative to each other. Look at the picture to confirm this. To make it easier, work in Local transformation mode. 

15. Adjust the connecting pivot points of bones by entering Bone Edit Mode and using the Select and Move tool under Local transformation. Once again, do not change the orientation of bones in Bone Edit Mode. 

16. When you are happy with the position of your bones, press the Select and Link tool. 

17. grab the bottom of each finger hierarchy and use the Select and Link tool by dragging it from the selected bones to the target bone which in this case is the wrist/hand bone (it operates as both the wrist and the hand for our rigging purposes). Now these bones rotate as children of the wrist/hand bone, which means if the hand/wrist bone rotates or moves, the finger bones will move along with it.

18. repeat the same steps as above for the thumb bone hierarchy.

19. Enter Bone Edit Mode again. Create a bone near the wrist/hand bone but do not attach it. This will be your “Wrist Rotator” bone. This bone will be very important. There is more than one way to make wrist rotation natural, but this method gives you a lot of control. 

20. Delete the Nub bone, exit Create Bone mode but stay in Bone Edit Mode. Select the wrist rotator bone you created. Select the Align tool you used earlier and click on the lower arm bone that connects to the wrist/hand bone. Set the Align Selection panel to Align Position and Align Orientation on all axes, as shown in the picture. Press OK.

21. in Local transformation mode, use the Move tool to drag the wrist rotator bone up to just below where you think the wrist should rotate. Use the Rotate tool to rotate the bone 90 degrees on its local axis. Make sure the bone is pointing in the same direction that the palm is facing, as shown in the picture. Use the Link tool to link the wrist rotator bone to the lower arm bone that it currently sits on. Now you have a wrist rotator bone that is connected to the lower arm and is directly centred on its pivot point.

22. Create a new bone and align it to 0,0,0 – this is your root bone. You need this for later when importing to UE4. There are different ways of doing the root bone but this is one legitimate way.

24. Look at my setup in the picture. The root bone is at the top of the hierarchy:

• Name your root bone “root_bone”
• Name the upper arm bone “r_arm_shoulder” (or “l_arm_shoulder” if you started building your bones on the left)
• Name the lower arm bone “r_arm_elbow” (because it swivels on the elbow joint)
• Name the wrist/hand bone “r_arm_wrist” (because it rotates on the wrist joint)
• Name the wrist rotator bone “r_arm_wrist_rotator” (this bone is separate to the wrist joint, its purpose is to separately control the gradual rotation of the whole lower arm up to the elbow)
• Name the fingers “r_finger”. Follow with their denominations: “index, middle, ring, pinky”. Within each finger, name each bone according to its order: “low, mid, high, tip”. Look at my setup to see how I have done it.
• Select all the bones APART FROM “root_bone”. Using the Layer Explorer in Hierarchy mode, drag all the bones INTO “root_bone”. Now the root bone is doing its job. 

25. Now you have a full arm skeleton. Feel proud. It’s time to mirror the arm. There is a cheap way to do this without having to use the inaccurate Offset dialogue:

• Enter Bone Edit Mode. Press CTRL+A to select all the bones (make sure nothing else is selected besides bones in the scene).
• Press “Mirror”. The mirrored bones should fill out the space where the opposite arm is located.
• Rename the bone prefix “R” to “L” and delete “(mirrored)”. There is a tool to do this for you but it’s fiddly.
• Delete “root_bone(mirrored)”.
• Move your new “l_arm_shoulder” hierarchy under “root_bone”.
• “r_arm_wrist_rotator” may not have mirrored correctly. If this is the case, delete the warped mirrored bone and manually mirror the bone yourself by repeating the previous steps and making sure the coordinates of both left and right wrist rotator bones match up.

26. Now you have two arms perfectly mirrored.

29. Add HI Solvers to the rest of the fingers. Correct the position of the IK goal from global to local transformation by using the Align tool on the “_high” bone and orienting the Z axis, so that the Z axis points right, the X axis points diagonally up and the Y axis points diagonally downwards. This will let you move the IK goal nicely and in the correct Local transformation. 

30. Use the Link tool to connect all the finger IK goals to the “arm_wrist” bone.

31. Test your IK chain by selecting them all and pulling them forward on the local Y axis. 

32. Set up another IK chain, connecting “arm_shoulder” to “arm_wrist”. 

33. Now we will make a controller for this IK chain and the wrist. In the Create panel top right, move to the Shapes tab. Stay on Splines and select Circle. Draw a spline circle onto the world.

34. Right click in the Modifier box. Convert to Editable Spline.

35. expand the Editable Spline dialogue. Select Spline. Press CTRL+A in the viewport. Hold SHIFT and rotate 90 degrees to create a new spline, and then another one until you have a full controller.

36. Press “Enable in Viewport” under Rendering on the rightside panel. Now you have a rendered version of your spline controller in the Viewport. Adjust the radial options to your liking. I go for 4 sides and a thickness of 0.4. If you need to scale your new controller, don’t do it with the normal Select and Scale tool – go into Spline under Editable Spline under the Modifier List and use Select and Scale from there. 

38. Align your new IK controller to the “arm_wrist” bone on all positional and orientational axes.

42. With the Attribute Holder modifier selected, press ALT+1 in the viewport. A parameter box will appear. Under UI Type, name the Parameter “ElbowSwivel”. Under Float UI Options, size the width to 100. Set the range from -10 to +10. Set the alignment to Right (or Left if you’re doing this on the left-handed arm). Press “Add” to add the custom attribute to the Attribute Holder modifier. It will appear on the right hand panel.

43. Go to the Animations tab and open the Reactions Manager window. With “arm_wrist_ik_controller” selected, press the green PLUS button at the top left. Then select “arm_wrist_ik_controller”. Navigate to Modified Object > Custom_Attributes > ElbowSwivel. You have now added the Master. Now select the wrist IK goal (the blue cross). Now press the white PLUS button on the top left of the Reaction Manager. Link it to the Swivel Angle value. Press the down arrow with the orange dot to add two new states. Set them as I have in the picture.

44. Rename the Attribute Holder to “Elbow Swivel Right” (or Left if you’re using the left arm). Try out your ElbowSwivel attribute. It should swing back and forth in a 180 degree arc. That’s now done, you have made a custom attribute to account for any potential awkward IK movement.

45. Create a new spline controller, this time with only one axis. Use the Align tool to align it to the wrist rotator bone, “arm_wrist_rotator_controller”.

46. there are several ways to constrain this setup. You can figure out your own or follow my steps. If you’ve deviated or done something slightly differently you can easily figure out your own way of making sure the controller and the bone stay fully connected. First, Link the wrist rotator bone to the elbow, or drop it under the elbow in the Hierarchy panel of the Layer Explorer. Link your wrist rotator controller to the elbow. Add an Orientation Constraint from the wrist rotator bone to the wrist rotator controller.

48. Now we will make a box that controls either arm of the skeleton without affecting the rest of the bones in the hierarchy. Go to the Create panel and make a Point Helper. Change its Display parameter to Box. Adjust its size to your liking. Align the point helper to the upper arm. With the upper arm bone selected, use a Position Constraint between the upper arm bone and the Point Helper. Rename the Point Helper as “shoulder_controller”, plus whether it’s left or right. 

You’ve got a full rig now that hopefully works well. Now it’s time to skin the mesh to the rig. If you have a base arm and multiple clothing items that go on top of the base arm, there is an extra step that I will show you at the end of part IV.

50. Unfreeze your base mesh and press CTRL+X to remove X-ray mode.

51. Go to the modifier list and add a Skin Modifier. Scroll down to the Bones section of Parameters. Press Add.

52. In the new window, select all the bones besides the fingertip bones and the root bone and confirm. 

53. Test out the skinning. In some places it may be incorrect, especially if your mesh and rig aren’t straight, so we will need to adjust it either by adjusting the envelopes or by painting weights. 

55. If your fingers are moving strangely, as you can see in Point 53, your wrist/hand bone may be affecting the finger bones. Move the wrist/hand bone envelope away from the fingers, or use the weight tools that I will describe in the following points below.

56. I don’t fiddle with the envelopes much–just enough to have a good approximation of the weighting so that the mesh deforms nicely when moving the rig. For finer control I prefer to weight the bones myself with the Weight Tool. Select Edit Envelopes and tick “Vertices” under “Select”. When you start editing the weights manually, modifying the envelopes themselves no longer works.

57. Scroll down under the modifier to “Weight Properties” and enable the Weight Tool.

58. Press F4 to enable edged faces. You can now select vertices and use the Weight Tool to weight them. Weight the fingers so that they have a value of 1 in the middle with a nice blended weighting to the bones either side. Experiment with the ring, loop, shrink and grow functions. It’s best to start on a low weight value of 0.1 or 0.25 and build up to red, or a value of 1. 

59. The most important adjustment you will make is to the “wrist_rotator” bone. As you can see in the picture, give it a large gradient with the greatest weight values centred around the wrist itself. Use the “Blend” button under the Weight Tool window when you’re happy with your weights to smooth them out. When you twist the rotator bone now, you will notice it has a long and gradual gradient to the elbow. This lets the animator offset the wrist movement against the movement of the hand for a more natural-looking mesh deformation. 

60. Some bone hierarchies will be awkward to weight properly. This whole process is just trial and error, so just be intuitive and you’ll eventually get the results you desire. 

62. It’s time to prepare the Max file for the animator. It’s much easier for the animator if the bones have a “Frozen Transform”. This means that if you set the transform to zero, the bones (and the mesh) will jump back to their original position. Grab all the Point Helpers, IK Controllers and IK Goals. Hold ALT+right click and select “Freeze Transform”. Accept the dialogue window that pops up. Now test it by moving an IK controller, then pressing ALT+right click and pressing “transform to zero”. It goes back to its original position. Very handy.

63. Select all the bones APART FROM the thumb bones, which have no IK Solver. Right click to freeze them. Now the animator can only transform the IK Controllers, IK Goals and Point Helpers which means there is less chance for a destructive accident to occur while animating and selecting things. 

65. If necessary, you can add the diffuse texture to the mesh. Unfreeze your Skinned mesh, press M, scroll down to Maps, tick Diffuse Colour and press “None”. Choose “Bitmap”, press “OK” and then select your own diffuse texture in the file browser.

66. If the texture isn’t showing, configure your viewport as in the image displayed. There’s no need for Realistic Materials with Maps or Normal/Bump maps because the animator doesn’t need the arms to look pretty and the framerate needs to be high.

First we’ll get in the skeleton and the arms. If you want to import a skeleton into UE4 it has to be with a skeletal mesh so we’ll import the arms along with every bone in the skeleton, including the weapon bones. So select the arms mesh and every bone and export them using ‘export selected’.

Now we’ve got our file containing the arms mesh and every bone of the skeleton. Import this into UE4 and make sure the ‘skeleton’ field is set to none so UE4 knows to generate a new skeleton for the import. You should get these two assets (and maybe a physics one but we don’t need that)

We set these variables by grabbing them from the player blueprint every tick so that they constantly update (except the player character, weapon and state anims variables since they don’t need to be kept up to date so much). We set the player character variable by calling “get player character, and using the return from that cast it to your specific player class. The return from this cast is what you should use to set the player character variable. Hook up these nodes to the” blueprint initialise animation” so it’s called whenever the animation blueprint is created. The weapon/state anims are set in a function that’s called whenever the player equips a weapon from the player blueprint class

Now we come to the anim graph. This a simplified anim graph that should fit well for you purposes. You can get more out of this like blending between animations (and we use that for playing animations on the left arm while holding a weapon, for example) but for now this will work.

The state machine ‘Movement’ is expandable and we’ll take a look inside in a second. This contains the logic to choose which state animations are played. We cache this just for easier use later, we can just call ‘Use cached pose ‘Movement Cache’’ since anim graph nodes can only ever output to one place. 

Create a node to play the idle animation. At first it won’t have the ‘Sequence’ and ‘Play Rate’ inputs, you can add these by selecting the node and in the details panel on the bottom right tick ‘as input’ on any variables you want to plug into. You can see here we plug in the idle state animations from state anims and the idle play rate into the appropriate inputs. ‘Sequence’ just means the animation to play. The “Kriss_idle” in the node name is just the default.

Now let’s go back and look at a transition from idle to run: 

Notice that most of them are ‘montages’: these are the animations that we’ll play using the slot in the anim graph. The others are used for the state anims played in the state machine. The type of montage variables should be set to ‘anim montage’ and the state anims variable type should be ‘anim sequence’.

Now how do we play these montages? The easiest way is to make a function in the weapon class. Call it ‘PlayMontage’. You can see it has one input, ‘montage’ which is an enum and an output which is simply the duration of the played anim montage.

To get the enum we need to create one of our own. Back in the content browser, click new, blueprint and choose ‘enumeration’. Open this up and add every type of animation you’ve got, then you can set this enum as the type of PlayMontage’s input and create the ‘Select’ node shown above.

Now the weapon class should already contain a skeletal mesh component, in our player blueprint we need to add a skeletal mesh component and set its mesh to the arms we imported at the start, along with setting it up with the anim blueprint we made already. 

However, the weapon is where the anim blueprint is actually being applied and the montages played, so we need to make the arms follow what the gun is doing at all times animation-wise. To do this we use a node ‘set master pose component’. In BLISTER we call this whenever a new weapon is equipped, setting the arm’s ‘master pose component’ to the newly created weapon. 

When you call the play montage function just select which type of animation you want to play. It will now play on both the weapon and the arms.