littlepixel
01-28-2005, 10:43 PM
I would like to propose an interesting application for dynamic curves in animation, when used in conjunction with blend-shapes. In essence we are able to use a dynamic spline IK in conjunction with a conventional (RPSolver/SCSolver) IK to effectively create a flexible form of IK to effect subtle secondary effects which would traditionally have to be keyed by hand. Although this method must necessarily suffer from its own technical challenges, I think it is an excellent example of the real power of the 'hair' module.
I will offer a short description of the technique in this post, but I will be happy to refine the technique through discussion in the forums. If I am not the first to be proposing this method, I pray at least I can describe MY OWN way of doing it, which I have devised just recently.
We begin with a simple character, 'Artemis the stunt man':
http://www.artsy.ca/artemis_00/001.jpg
We will be focussing on his arm in this tutorial. I create a spline IK, which I customarily do by creating my own CV curve. This isn't technically difficult, but I will not describe process presently, as I know the technique is rather common and the reader can consult various resources on the topic. I usually like to have CV's to land right on the joints and possibly a few extra cv's half way.
http://www.artsy.ca/artemis_00/002.jpg
In case you're wondering, once I create the CV curve, these are the settings I use for the spline handle:
http://www.artsy.ca/artemis_00/003.jpg
But we aren't ready to bind the curve just yet.. First we must make it DYNAMIC. Select the curve, and from the dynamics menu choose Hair->Make Selected Curves Dynamic. We will have to perform a few more operations from the hair menu, eventually we will use the 'Current' Hair curve for our Spline IK. (Each hair has three curves.. Start, Current and Rest.. more on this in a second).
http://www.artsy.ca/artemis_00/004.jpg
Once the curve becomes dynamic, we must select 'Hair->Set Rest Position->From Start'. (This is a menu I can't screen capture at present). Then we choose 'Hair->Display->Current Position'. Basically, when we make a curve dynamic, Maya will generate a Start Curve but no Rest Curve. We will need to manipulate the rest curve in a moment, but first we must use the CURRENT curve in our spline IK setup. Using the settings from above, we choose the Spline IK tool, select the end, tip and finally the current curve, and we have ourselves a dynamic curve spline controlling the arm dynamically. This can be verified by pressing either 'InteractivePlayback' from the hair shelf, or simple playback from the controls.
http://www.artsy.ca/artemis_00/006.jpg
NOTE: Pressing Play at this instant, the arm will move slightly but be stuck in place. We must choose our follicle and change the "Point Lock" channel to "Base" and this will release the tip to move freely. Pressing play, we can see the arm sag, due to gravity.
http://www.artsy.ca/artemis_00/007.jpg
Now in the next post I will demonstrate how to use a BLEND SHAPE on the 'Rest Curve' to effect secondary animation using a regular IK setup. Some of you I'm sure can guess ahead how I plan to do it, but I will hastily make the second post..,
http://www.cgtalk.com/showthread.php?t=206068 <- link to continuation
-Alex
I will offer a short description of the technique in this post, but I will be happy to refine the technique through discussion in the forums. If I am not the first to be proposing this method, I pray at least I can describe MY OWN way of doing it, which I have devised just recently.
We begin with a simple character, 'Artemis the stunt man':
http://www.artsy.ca/artemis_00/001.jpg
We will be focussing on his arm in this tutorial. I create a spline IK, which I customarily do by creating my own CV curve. This isn't technically difficult, but I will not describe process presently, as I know the technique is rather common and the reader can consult various resources on the topic. I usually like to have CV's to land right on the joints and possibly a few extra cv's half way.
http://www.artsy.ca/artemis_00/002.jpg
In case you're wondering, once I create the CV curve, these are the settings I use for the spline handle:
http://www.artsy.ca/artemis_00/003.jpg
But we aren't ready to bind the curve just yet.. First we must make it DYNAMIC. Select the curve, and from the dynamics menu choose Hair->Make Selected Curves Dynamic. We will have to perform a few more operations from the hair menu, eventually we will use the 'Current' Hair curve for our Spline IK. (Each hair has three curves.. Start, Current and Rest.. more on this in a second).
http://www.artsy.ca/artemis_00/004.jpg
Once the curve becomes dynamic, we must select 'Hair->Set Rest Position->From Start'. (This is a menu I can't screen capture at present). Then we choose 'Hair->Display->Current Position'. Basically, when we make a curve dynamic, Maya will generate a Start Curve but no Rest Curve. We will need to manipulate the rest curve in a moment, but first we must use the CURRENT curve in our spline IK setup. Using the settings from above, we choose the Spline IK tool, select the end, tip and finally the current curve, and we have ourselves a dynamic curve spline controlling the arm dynamically. This can be verified by pressing either 'InteractivePlayback' from the hair shelf, or simple playback from the controls.
http://www.artsy.ca/artemis_00/006.jpg
NOTE: Pressing Play at this instant, the arm will move slightly but be stuck in place. We must choose our follicle and change the "Point Lock" channel to "Base" and this will release the tip to move freely. Pressing play, we can see the arm sag, due to gravity.
http://www.artsy.ca/artemis_00/007.jpg
Now in the next post I will demonstrate how to use a BLEND SHAPE on the 'Rest Curve' to effect secondary animation using a regular IK setup. Some of you I'm sure can guess ahead how I plan to do it, but I will hastily make the second post..,
http://www.cgtalk.com/showthread.php?t=206068 <- link to continuation
-Alex