general question about CCD

[rimie23]

Hi,
i have general question about CCD i read that

A singularity problem might occur when the chain is completely straight and the target is
located on that alignment but between two joints

i did understand what that mean ?

[Kojack]

i did understand

Umm, CCD is usually Continuous Collision Detection, which is a way of detecting collisions that a discrete collision detection system would miss.

But your quote sounds like a problem with inverse kinematics where it doesn't know which way for joints to bend because they are colinear with the target point, which is unrelated to CCD.

Either way, it's something best asked on a physics engine forum since it's got nothing to do with ogre.

[rimie23]

yes i talk about ccd inverse kinematik
i asked here because there is how used it in ogre
so i said that maybe they can yndertaind what thant mean

[Kojack]

yes i talk about ccd inverse kinematik

What I was saying though is that CCD and inverse kinematics are different things. Your post title says CCD but the question is IK.

I believe the quote is talking about this:


In the top diagram, there's 4 rigid bodies connected together.
In the middle, Inverse Kinematics is used to make the end of the 4th body touch a target point (the red circle). While there's multiple ways of doing it, it should try to pick the way with the least amount of movement from the previous pose.
The bottom diagram shows a target point that is collinear (along the same line as the joints between the bodies) with and between the joints. Which way should the joints rotate to make the 4th body touch the circle? It could arch the bodies upwards like in the middle diagram, or it could arch them downwards. Both have equal movement, so neither is better. In 3D, there's an infinite number of equal ways to reach that point.

CCD, on the other hand, is about very fast moving objects jumping through walls (or other objects).

[cybereality]

I think the OP is actually asking about Cyclic Coordinate Descent (also CCD), which directly relates to IK.

Honestly just happened to be reading about it tonight, and I thought of this thread. Not sure I know enough to answer the question.

[Kojack]

Could be colony collapse disorder too.