Hello all,
So I've had this happen frequently since I started character rigging in Houdini a few months ago, and usually if I mess around enough it just goes away on its own, but now I need to get to the bottom of it.
So I'll have keyframes on some rigging elements (IK goals for instance), and in the animation editor and on the object's parameter values everything looks as it should. However, what I will see in the viewport is, for example, one IK goal at a particular keyframe just snap to some position far away from where it should be. Often times it is just for one frame, and will snap back to the right place on the next frame. It seems like this is a bug, because you can only notice this in the viewport - the translate values on this goal at this frame are correct.
I don't know why this happens. It often seems to happen when I move keyframes around though. In this case I noticed it after applying chops to my keyframes.
Anyone encounter this or have any ideas?
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Houdini Indie and Apprentice » Animation snapping in viewport
- mbbuckley
- 47 posts
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Technical Discussion » Basic rigging problem - Ik with constraints not matching goal when it is able to.
- mbbuckley
- 47 posts
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Thank you for your help Henry. Perhaps using a twist effector IK is the better option here. It did indeed cause problems with the pelvic bone included, but as you say, the pelvic bone lies perpendicular to the plane of the motion I would like to achieve, which I can understand would cause problems.
I think you are also right about the solver initially going the wrong way, as I before I began to limit the rotation ranges I remember that the leg appeared to work properly when bending in the backward direction.
Does anyone have any insight as to how the solver initially picks a direction to rotate in?
I think you are also right about the solver initially going the wrong way, as I before I began to limit the rotation ranges I remember that the leg appeared to work properly when bending in the backward direction.
Does anyone have any insight as to how the solver initially picks a direction to rotate in?
Technical Discussion » Basic rigging problem - Ik with constraints not matching goal when it is able to.
- mbbuckley
- 47 posts
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Hi Henry,
Yes, putting a slight bend in the knee does work. Instead of using the pre-transforms, I just added 15 degrees to the X rest rotation. Is this equivalent to your method?
However, this solution is not entirely satisfying. For one thing, I would like the leg to be able to be completely straight without having to turn off the IK. I'm going for more of a toony style. I don't see why the IK can't be given the indication of which way to bend without having to actually start it out with a bend.
Another practical thing is that I get a fair bit of snapping unless I use a higher rest rotation (~>15). For instance, at a rest X rotation of 5 the leg will stay straight until the goal is moved to a region where a rotation of roughly >15 is necessary, at which point it will snap from Rot X = 0 to Rot X = 15 and will increase from there.
Yes, putting a slight bend in the knee does work. Instead of using the pre-transforms, I just added 15 degrees to the X rest rotation. Is this equivalent to your method?
However, this solution is not entirely satisfying. For one thing, I would like the leg to be able to be completely straight without having to turn off the IK. I'm going for more of a toony style. I don't see why the IK can't be given the indication of which way to bend without having to actually start it out with a bend.
Another practical thing is that I get a fair bit of snapping unless I use a higher rest rotation (~>15). For instance, at a rest X rotation of 5 the leg will stay straight until the goal is moved to a region where a rotation of roughly >15 is necessary, at which point it will snap from Rot X = 0 to Rot X = 15 and will increase from there.
Technical Discussion » Basic rigging problem - Ik with constraints not matching goal when it is able to.
- mbbuckley
- 47 posts
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Hi all,
I am building a very basic character rig from scratch to get a better understanding of how houdini's bones/ik solvers work.
I have run into a perplexing issue. So I have a leg that is controlled by an IK With Constraints solver. I'm using the IKWC solver as opposed to the simple IK solver because I want to have a lot of control over the way that bones are able to rotate.
So for the leg, there are only three bones: a pelvic bone, a femur, and an ankle. The pelvic bone at this stage is just to give the femur proper distance from the spine so I have it static (all rotation ranges limits set to 0, for now). So this is essentially a two bone system. The bone are all orientated so that the X axis is the primary axis of rotation.
Its really basic what I want: I have it set so that the femur should rotate from 0-180 and the ankle can rotate from 0-180. This range allows for the leg to be lifted up in a going-up-a-step motion. And it can make this motion in this range if I turn the IK blend to 0 and set the rotations manually. However, when I turn the blend back up to 1, with the goal null where I want the end of the leg to be, it just keep the leg straight and does not match the goal. The goal is definitely attainable given the rotation ranges I allow, but it just won't figure this out.
Anyone have any idea whats wrong here?
I am building a very basic character rig from scratch to get a better understanding of how houdini's bones/ik solvers work.
I have run into a perplexing issue. So I have a leg that is controlled by an IK With Constraints solver. I'm using the IKWC solver as opposed to the simple IK solver because I want to have a lot of control over the way that bones are able to rotate.
So for the leg, there are only three bones: a pelvic bone, a femur, and an ankle. The pelvic bone at this stage is just to give the femur proper distance from the spine so I have it static (all rotation ranges limits set to 0, for now). So this is essentially a two bone system. The bone are all orientated so that the X axis is the primary axis of rotation.
Its really basic what I want: I have it set so that the femur should rotate from 0-180 and the ankle can rotate from 0-180. This range allows for the leg to be lifted up in a going-up-a-step motion. And it can make this motion in this range if I turn the IK blend to 0 and set the rotations manually. However, when I turn the blend back up to 1, with the goal null where I want the end of the leg to be, it just keep the leg straight and does not match the goal. The goal is definitely attainable given the rotation ranges I allow, but it just won't figure this out.
Anyone have any idea whats wrong here?
Houdini Indie and Apprentice » Timeshift or offset animation on points
- mbbuckley
- 47 posts
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Thank you both. I appreciate the different approaches. Have to say I am glad I'm getting into Houdini at a time when the channel wrangle is a thing. I actually was heading down a chops path to a solution before I saw your replies (i am becoming a big fan of of them). You both got me over the finish line. Cheers.
Houdini Indie and Apprentice » Timeshift or offset animation on points
- mbbuckley
- 47 posts
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Hello, new user here. Simple problem that I've done a lot of looking around for answers to but haven't found anything that works for me yet. I want to offset the keyframed animation of N number of points. My current approach is to create an attribute called “offset” and then use a foreach loop with a timeshift node embedded in it. My expression for the frame in the timeshift node is
$F+point(“../foreach_begin1/”, 0,“offset”, 0)
This does not work. I've experimented with copy stamping and chops as well. Copy stamping doesn't really work for me because it is the timeframes of the points I want to offset, not the timeframe of the object I'm copying onto them. Chops I just don't really understand well enough…I don't know how to drive them with geometry attributes.
I'd like to know why my current approach using the for each loop doesn't work. But I'm very open to any suggestions on other approaches. Thank you for your time.
$F+point(“../foreach_begin1/”, 0,“offset”, 0)
This does not work. I've experimented with copy stamping and chops as well. Copy stamping doesn't really work for me because it is the timeframes of the points I want to offset, not the timeframe of the object I'm copying onto them. Chops I just don't really understand well enough…I don't know how to drive them with geometry attributes.
I'd like to know why my current approach using the for each loop doesn't work. But I'm very open to any suggestions on other approaches. Thank you for your time.
Houdini Indie and Apprentice » Is there an equivalent of Maya's Time Editor in Houdini?
- mbbuckley
- 47 posts
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I have the same question. The time editor was a great addition to Maya. You can basically create an animation sequence, like a walk cycle, and then blend it into another sequence, like throwing a ball, and then blend back into the walk cycle. Interface very similar to a non-destructive video editor like final cut. Just animation clips instead of video clips. Would love to see something like this if there is nothing like it currently.
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