Dummy Joint not working as it should
by Kevin Roberts · in Artist Corner · 08/26/2005 (4:44 pm) · 9 replies
Hello again,
I'm trying to get a walking animation working with the body of the robot moving up and down. I've been told by Joseph that the root bone is always in a fixed position. He suggested creating a "dummy" bone which would be the ultimate root bone in the chain, while my torso bone becomes movable. Anyway, I can't seem to set it up right. I have a bone in the armature named Dummy which is the parent of Torso, but it doesn't work. I've tried both IK and FK, neither of which working. In IK, I can't move the torso bone up and down when in pose mode, it only rotates when I press the G-key for grab; in FK, the show tool seems to erase a bone from existence, keeping the rotation of the torso in the animation, but erasing any locational change.
Help would be appreciated :P.
Thanks,
Kevin
I'm trying to get a walking animation working with the body of the robot moving up and down. I've been told by Joseph that the root bone is always in a fixed position. He suggested creating a "dummy" bone which would be the ultimate root bone in the chain, while my torso bone becomes movable. Anyway, I can't seem to set it up right. I have a bone in the armature named Dummy which is the parent of Torso, but it doesn't work. I've tried both IK and FK, neither of which working. In IK, I can't move the torso bone up and down when in pose mode, it only rotates when I press the G-key for grab; in FK, the show tool seems to erase a bone from existence, keeping the rotation of the torso in the animation, but erasing any locational change.
Help would be appreciated :P.
Thanks,
Kevin
#2
08/27/2005 (8:03 am)
Hey, I'm using the bone with no IK link, and it's exporting as [parent -1] which is what it should be, but all locational animation dissappears in the animation. Once again I'm stuck :(.
#3
08/27/2005 (5:43 pm)
Question: Is the dummy bone supposed to show up in the ShowTool Pro? Because there is only one bone where the torso and dummy bone should be. 
#6
The exporter uses the head position of the bone, transformed into its parent's space (since blender define's head's relative to the previous bone's tail). It also scales the position and rotation. However, if the armature is scaled, it does not scale the animation tracks (i'm not sure if this is requied, perhaps someone can test and see if this screws up?)
The end tail of the bone is not required, since as you say, torque nodes are only a single point in space. The last point of a chain you see in torque *is* the last bone in the chain in blender - its got the rotation, so anything you mount to it has the correct rotation, but you wouldn't be able to mount anything where the tail position is, unless you offsetted it by the vector :
[0, length of (bone's head position - bone's tail position) ,0]
(Assuming the offset takes into account the bone's rotation)
Now, i could add these endpoints if i wanted to, but i wouldn't have anything to call them. Equally, i couldn't add in all the rest of the tail positions since it'd likely be pointless and a waste of space :)
The exporter used to export the armature root position as a node, but that is now collapsed into the root node(s) of the armature - perhaps if i make the toggleable, it will facilitate the requirements of a "Dummy" bone? (i haven't looked into this particular issue much).
The point you see on the bottom is the "Root" node, which is used to capture meshes with no vertex influences (like the collision meshes).
Anyway, i hope that helps.
P.S. does that rig animate correctly?
08/28/2005 (1:55 am)
Joseph,The exporter uses the head position of the bone, transformed into its parent's space (since blender define's head's relative to the previous bone's tail). It also scales the position and rotation. However, if the armature is scaled, it does not scale the animation tracks (i'm not sure if this is requied, perhaps someone can test and see if this screws up?)
The end tail of the bone is not required, since as you say, torque nodes are only a single point in space. The last point of a chain you see in torque *is* the last bone in the chain in blender - its got the rotation, so anything you mount to it has the correct rotation, but you wouldn't be able to mount anything where the tail position is, unless you offsetted it by the vector :
[0, length of (bone's head position - bone's tail position) ,0]
(Assuming the offset takes into account the bone's rotation)
Now, i could add these endpoints if i wanted to, but i wouldn't have anything to call them. Equally, i couldn't add in all the rest of the tail positions since it'd likely be pointless and a waste of space :)
The exporter used to export the armature root position as a node, but that is now collapsed into the root node(s) of the armature - perhaps if i make the toggleable, it will facilitate the requirements of a "Dummy" bone? (i haven't looked into this particular issue much).
The point you see on the bottom is the "Root" node, which is used to capture meshes with no vertex influences (like the collision meshes).
Anyway, i hope that helps.
P.S. does that rig animate correctly?
#8
As for the Root node situation, here is what i have figured out so far :
- The exporter will collapse the transform of the armature into the root bone(s) of the armature
- Any animation tracks you have animating the root bone(s) will be relative to the original position, not the collapsed one
- When torque comes to animate the bone (rather, node), the transform will likely be incomplete or otherwise screwed
I'll probably add a toggle to the exporter to tweak this behaviour. I only added it in because i was concerned about the amount of nodes that the exporter was chugging up when using multiple armature's (e.g. on a vehicle shape).
Likewise, a similar situation is happening with the scaling :
- The exporter will apply the scale of an armature to each of its bones (torque only has location and rotation rest positions).
- Any animation tracks you have animating the bones will be relative to the original position, not the scaled one
- When torque comes to animate the node, the transform will likely be incomplete or otherwise screwed
08/28/2005 (9:57 am)
Ok Joseph, i'll try and fix the animation for the next release.As for the Root node situation, here is what i have figured out so far :
- The exporter will collapse the transform of the armature into the root bone(s) of the armature
- Any animation tracks you have animating the root bone(s) will be relative to the original position, not the collapsed one
- When torque comes to animate the bone (rather, node), the transform will likely be incomplete or otherwise screwed
I'll probably add a toggle to the exporter to tweak this behaviour. I only added it in because i was concerned about the amount of nodes that the exporter was chugging up when using multiple armature's (e.g. on a vehicle shape).
Likewise, a similar situation is happening with the scaling :
- The exporter will apply the scale of an armature to each of its bones (torque only has location and rotation rest positions).
- Any animation tracks you have animating the bones will be relative to the original position, not the scaled one
- When torque comes to animate the node, the transform will likely be incomplete or otherwise screwed
Torque Owner Redacted