Global rotation of joints

B@z · Post by **B@z** » Tue Apr 13, 2010 10:37 pm

Hi
i have a problem with rotation joints.
is it possible to rotate joint like in the modelling software when using global rotation.
i want to make my character's back point to a special direction (when shooting up, i want my character's back rotating up, etc)
thanks

B@z · Post by **B@z** » Thu Apr 15, 2010 11:24 am

help please >< (bump)

Adler1337 · Post by **Adler1337** » Thu Apr 15, 2010 1:14 pm

i have a problem with rotation joints.
is it possible to rotate joint like in the modelling software when using global rotation.
i want to make my character's back point to a special direction (when shooting up, i want my character's back rotating up, etc)

Why do you need global for that?

B@z · Post by **B@z** » Thu Apr 15, 2010 5:11 pm

ok let me explain u with pictures.
http://dotdotdot.site90.com/FTP/pic1.jpg
the first picture the shooting with pistol. as u see, i have to rotate it on the X axis, to make it point up or down

http://dotdotdot.site90.com/FTP/pic2.jpg
second picture is the revolver shooting. as u see, if i rotate on the X axis ( http://dotdotdot.site90.com/FTP/pic3.jpg picture 3) it seems bad.

http://dotdotdot.site90.com/FTP/pic4.jpg
4th picture shows what happens if i rotate on a global X axis. everything ok.

i want to achieve that rotation

Adler1337 · Post by **Adler1337** » Fri Apr 16, 2010 1:01 pm

Sorry your pictures aren't helping me much. What bone are you trying to rotate? You should be able to rotate that bone with setRotation(). Just get the rotation of the bone you want to rotate and rotate it by however much you want.

Adler1337 · Post by **Adler1337** » Fri Apr 16, 2010 1:09 pm

If you really need global you can try using getAbsoluteTransformation() and get the rotation from the matrix using getRotationDegrees().

B@z · Post by **B@z** » Fri Apr 16, 2010 1:15 pm

um... just check pic2 and pic3.
and check the arrow
the camera is from front. see where does the X axist point? if i rotate on that axis, the arm of my model wont point to center, but will move left or right (pic3)
ill make you a better picture
http://dotdotdot.site90.com/FTP/pic5.jpg
a little explainment: the first picture is the normal. check the red line, thats the line where the arm should move.
the second picture is the rotating on local space (how setRotation works).
see the arm? its moving to side. thats fugly
third picture is the rotating on global space (what i want to achieve), the arm is perfectly on the line, and looks good!

B@z · Post by **B@z** » Fri Apr 16, 2010 1:21 pm

oh posted before reading ur second post.
with getAbsoluteTransformation i can GET the global rotation, but i want to SET it on a global axis
i dont know how to calculate that rotation.

Adler1337 · Post by **Adler1337** » Fri Apr 16, 2010 2:11 pm

If you set the rotation, this is relative to its parent. If you don't have a parent for that node, rotation is global. Rotation is not changed incrementally!

I would try setting the bone you are trying to rotate to have no parent and call setRotation().

B@z · Post by **B@z** » Fri Apr 16, 2010 3:12 pm

yeah and then if i rotate my character (for example when falling back), then my characters torso wont move..
....
ok lets start it from the beginning.
if u open a modeling software. u make a skeleton.
u select a joint. press rotation. then u can change either rotating locally (irrlicht setRotation function), or rotating globally.
that is what i want to achieve. the rotating on global axis.
can anyone help me with that?? (and not asking "why u need that" etc)

Lonesome Ducky · Post by **Lonesome Ducky** » Fri Apr 16, 2010 9:31 pm

The IBoneSceneNode* has a member function setSkinningSpace, and you can pass global to it. E.G.

Code: Select all

IBoneSceneNode* bone = node->getJointNode(0);
bone->setSkinningSpace(EBSS_GLOBAL);

B@z · Post by **B@z** » Sat Apr 17, 2010 12:30 am

hm i see no difference
i tried either

Code: Select all

			IBoneSceneNode* back = upperAnimNode->getJointNode("hip_up");
			if (back)
			{
				vector3df currot = back->getRotation();
				back->setSkinningSpace(EBSS_GLOBAL);
				back->setRotation(vector3df(currot.X+vertical, currot.Y, currot.Z));
			}

or setting the skinning space when loading. it was absolutely same as when i set it to EBSS_LOCAL

B@z · Post by **B@z** » Sat Apr 17, 2010 11:55 pm

any other ideas? (bump!)

B@z · Post by **B@z** » Mon Apr 19, 2010 7:29 pm

am i trying the impossible!?

Adler1337 · Post by **Adler1337** » Mon Apr 19, 2010 10:44 pm

I looked at your pictures again and i don't see why you can't do that with setRotation(). It looks to me that your axes are swapped or something. Try switching the axes around until you get it to move up and down instead of side to side.