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Index › Programming Questions & Help › Programs › I get lost in multiple rotations
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I get lost in multiple rotations (Read 564 times)
.ben
I get lost in multiple rotations
Jun 23rd, 2008, 1:34pm  
Hi,

I try to program a rolling sphere, with a character in it. The sphere's going in every direction of the xz-plane, however, I get lost in the rotateZ and rotateX calls, because they affect each other(, and probably I even have to rotate around the Y axis...). I've also used sin and cos to include rotateX's influence on rotateZ, I can't get a satisfying result.
You can find the sketch and source code at:

http://benmeijering.nl/p5/applet/

Any help is appreciated.

~ Ben
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antiplastik
Re: I get lost in multiple rotations
Reply #1 - Jun 24th, 2008, 11:18am  
hey, shouldn't you use quaternions? since you need to rotate your sphere around specific axes, I think this is the solution. it's often useful when you're stuck with (x, y, z) rotations.
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.ben
Re: I get lost in multiple rotations
Reply #2 - Jun 25th, 2008, 10:11am  
antiplastic, thanks!
these quaterniouns seem very promising; very mathematical, but luckily some p5 people already dug into the matter, thanks!
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antiplastik
Re: I get lost in multiple rotations
Reply #3 - Jun 25th, 2008, 11:53am  
yes, I used them already to display 3D animated characters. you could easily reuse some methods from the sketch :
http://n.clavaud.free.fr/processing/SimplePickingPlusAnimation/

especially these classes : Quat4f and AxisAngle4f

if I remember well, I used quaternions for some rotation calculations, then converted the result into (axis,angle) format and just called rotate(angle, x, y, z) to get the appropriate rotation in Processing.
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.ben
Re: I get lost in multiple rotations
Reply #4 - Jun 25th, 2008, 9:42pm  
Antiplastik, thanks!
I'll definitely take a look at it and see if I'm able to understand the idea behind the code, to be able to reuse it.
As soon as I have managed so, I'll make a post.
* Great sketch btw. I once thought about making a bvh-file interpreter, to animate characters, using mocap data. You've done it algorithmically: nice!

~ Ben
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