Terry Brunt - Computer Animation Arts: Maya Tutorials

Showing posts with label Maya Tutorials. Show all posts

Friday, 6 November 2020

Maya Tutorials - Session 2

We went through three different rigging tutorials this time, so I can't think of a fitting title.

Anyway, as is the norm, lesson started with a 5 minute Moom posing challenge.

Comparing the Moom I posed to the reference, you can see what I've missed out on.

Moom is too rigid, where as the ref's spine is slightly tilted to the side.

I never got around to posing the hands.

I forgot to pose the feet and the knees are a bit too bent, resulting in Moom looking like they've just landed from a jump, rather than going into a jump, like the reference.

At least Moom isn't injured this time.

On to the actual lesson.

Task 1: Curve Driven Squash & Stretch

Starting with the familiar torso of Jetpack Jones.

When rigging JPJ you make a ribbon spine, in this ribbon spine is a specific curve. This curve is used to create a custom node, a curve info node, used to make squash and stretch work with the model. To create this node type "arclen -ch on ribbon_volume_driver_crv" into the MEL command line. Once executed, bring the curve into the node editor.

Here is the node editor with the ribbon curve fully graphed out.

Going back to the ribbon spine, select the three control joints and bring them into the node editor.

Here is everything laid out so far.

Just like the tutorials from last week, three multiply/divide nodes are needed to get this to work. One normaliser, then one for the square root, and then a last one to divide. In the actual lesson, Alan did show us how to change each joint individually, however I can't remember how he did this, so I'm not going to have a very good squash.

But here we have Stretch Pack Jones.

Task 2: No Flip Pole Vector

Back to the half rig from last week, we look at the leg this time.

The leg rig has a separate control for the knee, which is gives more control for animating, but it can be a bit of a pain when trying to do something simple, like walking.

Delete the knee control and set all the pole vector values to 0.

Bring out the pole vector's X value. Also add a "Twist Ctrl" attribute to the foot control.

Bring the leg IK and the foot control into the node editor, as well as adding a plus/minus/average node.

Plug the foot control's Twist Ctrl into PMA input 1D[0]. Plug the leg IK's Offset into input 1D[1]. Then take output 1D and plug it into the IK's Twist. Make sure to set the IK's offset to 90 at this stage.

If it all worked, you should now be able to control the knee from the foot control.

Task 3: IK/FK Switch

Starting with this half a torso.

Duplicate from the shoulder joint twice.

Delete the fingers from the duplicates, as we'll only need the shoulder, elbow & wrist joints. Rename each chain (Bind, IK & FK). Individually parent each IK/FK shoulder & elbow to their Bind counterparts. Connect the wrists with point and orient constraints.

Create a locator and place it above the shoulder. Add attribute: L_Arm_IK_FK. This is the switch. Using set driven keys, connect the locator to the IK and FK constraints.

Added IK handle from the IK_shoulder to the IK_wrist.

Added control for the IK

Added pole vector and elbow control for the IK

Added FK controls

Added hand control to the IK

Complete FK controls

Complete IK controls

Thursday, 29 October 2020

Maya Tutorials - Squash and Stretch

Final year, no graded toolkit, that however doesn't mean the lessons stop.

In this first session there was three tasks to do, starting with a five minute pose challenge with moom. Unfortunately I was unable to do this challenge due to technical issues, but the situation was sorted as we moved onto the actual lesson.

Part 1: Basic Squash, Stretch & Volume Preservation

Starting with an already rigged toadstool. Geometry layer hidden to show only the skeleton. Using the distance tool to measure the total length of the skeleton coming to 8 units. The locators in from the measure are then to be parented under the controls.

Import all 6 joints in the rig as well as the distance shape into the node editor. From there add 4 extra multiply/divide nodes. The first multi/divide node is used to control the squashing and stretching. Use it to divide the total length by itself to feed back into the joints. To create the volume preservation, the 3 other multi/divide nodes are needed. The first node is the "normaliser", it's used to create a value of 1 by dividing the distance by itself, just like the last multi/divide node. The next node is the square root, this is achieved by updating the output from the normaliser by the power of 0.5. The output from that node should then go into input 2 of the final multi/divide node. This node is to divide the input by 1, resulting in the final number that can be connected into the joint nodes, scale Y & Z.

Normal Toadstool

Squashed Toadstool

Stretched Toadstool

Part 2: Conditional Squash & Stretch

Starting with this pre-made arem, measurement is taken from the shoulder to the wrist. This time the locators are to be constrained rather than parented, this is to prevent a feedback loop.

Only the distance tool shape and the shoulder & elbow joints are imported into the node editor. From here a multi/divide node and a condition node are needed. Connect the distance to the multi/divide input 1X, this will give you the tools length, however it is not the true length of the arm because of a slight bend required for rigging. To get that number add the translate X values of the elbow and wrist together. This total distance should go be written into input 2, then the output X should be connected to "Colour if True R" on the Condition node. The distance should also be connected to the condition node's first term. From ensure that the condition node's first term is the measured distance and its second term is the true distance, once that's in place set the condition node to "Greater than or Equal to". You can then connect the Out Colour R to the Shoulder and Elbow nodes, Scale X.