IK settings missing dir joint?

[Ishtvan]

Our ik settings are missing a "dir" joint.

 

 

The vector from the ik_knee joint to the ik_dir joint specifies the direction the walk IK will bend knee.

(From here: http://www.iddevnet.com/doom3/walkik.php)

 

These are our ik settings:

"ik_numLegs" "2"
"ik_minWaistAnkleDist" "16"
"ik_footSize" "4"
"ik_waist" "Hips"
"ik_hip1" "LeftUpLeg"
"ik_hip2" "RightUpLeg"
"ik_knee1" "LeftLeg"
"ik_knee2" "RightLeg"
"ik_ankle1" "LeftFoot"
"ik_ankle2" "RightFoot"
//"ik_dir1" "LeftFoot"
//"ik_dir2" "RightFoot"
"ik_foot1" "LeftToeBase"
"ik_foot2" "RightToeBase"

 

It looks like we have everything except for the "dir" one, which is commented out, maybe because we couldn't find the right joint for it? The Doom3 creatures have unique knee joints, for example:

"ik_dir1"		  "Lknee"
"ik_dir2"		  "Rknee"

 

Our skeleton doesn't have these knee joints. I don't know how critical this is. IK seems to work, but I'm not sure if we're seeing undefined behavior when we don't put in an ik_dir or what. Does our skeleton have anything resembling the knee joints on the D3 skeletons? If not, is it okay to be missing that joint, or do we have to add it? If so, we should add it now rather than later.

[Springheel]

It doesn't look like we've ever had them set, and I've never noticed any problems with the way the knee bends with our AI. Maybe it's only needed for AI that have knees that can bend in weird ways or something.

[Ishtvan]

I'd have to look at the IK code to see what happens when you don't put in a dir joint. It probably defaults to some behavior, which seems to work for now but might not work in all situations.

[Ishtvan]

Okay, I looked at the source, and if you don't input ik_dir, it does this:

 

// get the IK direction
if ( dirJoints[i] != INVALID_JOINT ) {
dirOrigin = joints[ dirJoints[ i ] ].ToVec3();
dir = dirOrigin - kneeOrigin;
} else {
dir.Set( 1.0f, 0.0f, 0.0f );
}

 

In other words, it assumes that the front of the knee is facing in the direction (1,0,0), which is straight forward. I guess that's okay for our purposes. If we make any backwards-bending kneed AI later (steambots, horses?), they'll need a dir joint to specify that.

[ascottk]

The spider needed the dir joint so I had to add them to the spider's skeleton in order to get the walking animations and walk ik working:

http://forums.thedarkmod.com/index.php?s=&am...st&p=107450

[Ishtvan]

I guess that makes sense since their knee would be facing out sideways instead of straight forward in the direction they're looking. Do you think we're okay in the current situation where humans don't have the knee joint and we just assume the knee hinges on an axis facing straight forward?

 

What if the upper leg is bent at the hip? Wouldn't that put the straight-legged knee at a different angle than straight ahead? In other words, imagine a person standing straight. Okay, their knee is facing straight forward. But now if they raise up one leg while keeping it straight, the knee angles up (facing up when the leg is held out all the way at 90 degrees). But our rig still thinks the knee is facing straight forward, because we have no knee joint that would rotate along with the upper leg and act as a reference. Couldn't that cause some inaccuracy in the walk IK? Is this having any effect on the current run cycle?

 

I don't know if this is a problem though, do the D3 knee joints rotate with the upper leg, or are they parented to the lower leg?

[ascottk]

The knees on our rig are joint1 (left) and joint2 (right). Unfortunately they need to be reexported because they are not included in the conversion. The internet connection I've been raiding is not reliable so if you need to experiment someone needs to exportmodels with joint1 and joint2 added in the def file (builder guard):

 

options -keep Hips LeftHips_Dummy LeftUpLeg LeftUpLegRoll LeftLeg joint1 LeftLegRoll LeftFoot LeftToeBase joint3 joint4 RightHips_Dummy RightUpLeg RightUpLegRoll RightLeg joint2 RightUpLegRoll RightLegRoll RightFoot RightToeBase joint5 joint6 Spine_Dummy Spine Spine1 Spine2 LeftShoulder_Dummy LeftShoulder LeftArm_Dummy LeftArm LeftArmRoll LeftForeArm LeftForeArmRoll LeftHand LeftHandIndex1 LeftHandIndex2 LeftHandIndex3 joint12 LeftHandRing1 LeftHandRing2 LeftHandRing3 LeftHandRing4 LeftHandThumb1 LeftHandThumb2 LeftHandThumb3 Neck Head RightShoulder_Dummy RightShoulder RightArm_Dummy RightArm RightArmRoll RightForeArm RightForeArmRoll RightHand RightHandIndex1 RightHandIndex2 RightHandIndex3 joint14 RightHandMiddle1 RightHandMiddle2 RightHandMiddle3 joint13 RightHandThumb1 RightHandThumb2 RightHandThumb3 leftpad rightpad joint7 sword -sourcedir models/model_src/builder_guard_mb -destdir models/md5/chars/builders/guard

 

According to maya the joints comes after the upper legs (LeftLeg joint1, RightLeg joint2). I commented the ik_dir out on my initial def files because I didn't understand how they worked at the time.

[Springheel]

Are you talking about the new rig, the old rig, or the really old original rig?

 

There have been a lot of changes to the AI over the past year or two. We don't even use models/model_src/builder_guard_mb anymore (though it's possible the same joints are present in the new rig).

[ascottk]

Are you talking about the new rig, the old rig, or the really old original rig?

 

There have been a lot of changes to the AI over the past year or two. We don't even use models/model_src/builder_guard_mb anymore (though it's possible the same joints are present in the new rig).

 

I have no idea The same skeleton used in the different sized animations. The new builder guard I'm working on is using the medium animations without problem. I was using the new builder guard def as an example. BTW, what happened to the ik_dir decls in the def files?

[Springheel]

The same skeleton used in the different sized animations.

 

That's the "old" skeleton, which is based on the even older citywatch skeleton (which I believe is the one you worked on a while back). If models/model_src/builder_guard_mb uses the same joint names and basically the same positions, you might not notice any obvious problems. However, that skeleton is not being worked on anymore as we move animations and characters over to the new rig Squill has created.

[ascottk]

That's the "old" skeleton, which is based on the even older citywatch skeleton (which I believe is the one you worked on a while back). If models/model_src/builder_guard_mb uses the same joint names and basically the same positions, you might not notice any obvious problems. However, that skeleton is not being worked on anymore as we move animations and characters over to the new rig Squill has created.

Where's the new rig? I looked all over the forums to find more info but I found very little about it.

[Springheel]

This is the (lengthy) thread about it. http://forums.thedarkmod.com/index.php?showtopic=7263 There are still a few issues to be worked out before it is finalized.

[ascottk]

This is the (lengthy) thread about it. http://forums.thedarkmod.com/index.php?showtopic=7263 There are still a few issues to be worked out before it is finalized.

Yeah, I couldn't make heads or tails out of it

[Springheel]

The new skeleton is being used by the proguard, currently, and I think the most recent version is in the models_src folder. However, there are still a few things that need to be modified...I think Squill is planning to add a couple new joints to the knees and perhaps rotate the head bone.

[ascottk]

The new skeleton is being used by the proguard, currently, and I think the most recent version is in the models_src folder. However, there are still a few things that need to be modified...I think Squill is planning to add a couple new joints to the knees and perhaps rotate the head bone.

The rig needs the joints that stick out of the thighs to animate the tunics and stuff (the lower part of the cloth touches the leg when stepping up instead of floating above the leg). oDD is the one that told me about their purpose & the proguard lacks those joints. I wish I was around during this debate just so we could avoid headaches like this. Besides, isn't it late in the game?