sirogi Posted August 9, 2002 Share Posted August 9, 2002 and here's the file... for those who care cube_roll.zip Quote Link to comment Share on other sites More sharing options...
mir Posted August 14, 2002 Share Posted August 14, 2002 hi everybody... i'm kinda new to this forum (this is my first posting!!) i solved the first two challenges... rolling cube and rolling cubes with different velocities and sizes... i tired out the rotating 90degrees and popping it back again into place...it worked out fine but its gonna look silly if u have texture on it... so then i tired this new approach....have the cube rotate about its pivot and move it up and down accordingly so that it seems that the edge is always touching the floor...then move the cube ahead with the same speed as the rotation speed... this approach is working just fine... there r no key frames and everything is procedural...u can change the size and the velocity on the fly... i'll be posting the animated file next...( as soon as i make one) currently working on the third challenge.. this is fun!!! Quote Link to comment Share on other sites More sharing options...
TheUsualAlex Posted August 14, 2002 Share Posted August 14, 2002 Hey there Mir, Glad to see you here. Exarhos told me about you. I'd love to see what kind of crazy mathematical solution you came up with. Cheer to ya, Alex Quote Link to comment Share on other sites More sharing options...
ivan Posted August 14, 2002 Share Posted August 14, 2002 Using oriented bounding boxes would allow you to arbitrarily rotate your cubes in any direction... you just get the eigenvectors of a covariance matrix, and that'll give you a 3X3 rotation matrix, then you can get the min/max to figure out the center point, and voila! a thousand lines of code! actually, you already have the rotations, you could just use their dot product trick to get the collision distance... hmm... ftp://ftp.cs.unc.edu/pub/users/manocha/PA...ISION/sig96.pdf Quote Link to comment Share on other sites More sharing options...
TheUsualAlex Posted August 15, 2002 Share Posted August 15, 2002 For the 3rd time... I am lost... Quote Link to comment Share on other sites More sharing options...
tuangD Posted August 15, 2002 Share Posted August 15, 2002 oh alex me too.. far more lost there cheers -tuang PS, that's pdf file is amazing!!!! really love to know them more! Quote Link to comment Share on other sites More sharing options...
plan9 Posted August 15, 2002 Share Posted August 15, 2002 the martians have landed! Quote Link to comment Share on other sites More sharing options...
TheUsualAlex Posted August 15, 2002 Share Posted August 15, 2002 HAHAHAHAHAH ROTFLOL sorry... you cracked me up. Good timing. Quote Link to comment Share on other sites More sharing options...
sirogi Posted August 15, 2002 Share Posted August 15, 2002 Awesome link, Ivan! got my noodle baking... you could just use their dot product trick to get the collision distance... that trick is very yummy, but from what I've understood, it just returns a test result, wether you have an overlap or not... And to actually find where in time the overlap occurs, you'd have to iterate those tests in order to converge on an accurate solution....either that or just accept the first frame of overlap as being the "collision" frame...right? check this out (if you haven't already): http://www-rocq.inria.fr/~redon/research.htm stuff dreams are made of!.....that's the kind of functionnality I don't dare to ask for in houdini....maybe....some day....our kids... collision detection from mars, anytime soon? cheers. PS: having a box roll in one direction on a flat plane is cool...but like Jens said, over rolling hills is better and what if I want to steer my box around? AIeee....brain...hurts... these are the times one wishes for good RBD in houdini .... ~sigh~ Quote Link to comment Share on other sites More sharing options...
tuangD Posted August 15, 2002 Share Posted August 15, 2002 that's a cool link sirogi, by the way love your totoro!!! and for ivan I have a question, if it not to hard to explain... you already have the rotations, you could just use their dot product trick to get the collision distance... for my understanding dot product returns the cosine of the angle between two normalized vectors. can you explain to me how can you use it to get the collison distance.. thanks a lot... cheers -tuang Quote Link to comment Share on other sites More sharing options...
sirogi Posted August 16, 2002 Share Posted August 16, 2002 yeah, totoro is teh best (these are actually his 2 helpers...) as for the dot product, it doesn't actually *get* the distance between the bounding boxes, it's part of a bigger solution that these people came up with to check for overlapping bounding boxes, basically it's a trick to check for interference of 2 objects...if you carefully go through -section 5- of the pdf ivan pointed, you should see how the dot product is used in a quite creative way..... cheers! Quote Link to comment Share on other sites More sharing options...
tuangD Posted August 16, 2002 Share Posted August 16, 2002 Thanks sirogi, I'll try to follow it, hope it not too hard... cheers, tuang PS. sirogi have you seen "kiki's delivery service" it's nice too :> Quote Link to comment Share on other sites More sharing options...
sirogi Posted August 16, 2002 Share Posted August 16, 2002 he he he......my other avatar option was jiji Quote Link to comment Share on other sites More sharing options...
tuangD Posted August 16, 2002 Share Posted August 16, 2002 oh ha ha ha I should have known.. -tuang Quote Link to comment Share on other sites More sharing options...
anakin78z Posted August 20, 2002 Author Share Posted August 20, 2002 Aaaaaargh!!!!!!! Had the friggin thing rolling over a hill..... did I hit Alt+S? Of course not. Did houdini crash on me? Of course it did. Do I have time to recreate it real quick? No way. Sigh... Maybe tomorrow. Quote Link to comment Share on other sites More sharing options...
steveJB Posted September 16, 2003 Share Posted September 16, 2003 can i have a hint?? Id like to try and do it today?!! steveB Quote Link to comment Share on other sites More sharing options...
anakin78z Posted September 16, 2003 Author Share Posted September 16, 2003 it's been a while... I can hardly remember... check out the bbox expression. That'd be my first hint. (although you may approach it tottally differently ) Quote Link to comment Share on other sites More sharing options...
krets Posted September 25, 2003 Share Posted September 25, 2003 I don't know about simple, but the cubes do not slip. if( ch("./rz")<0 ,ch("./sx")-sin( 90*(ch("./rz")/90-int(ch("./rz")/90)) +45)*(sqrt(2*(.5*ch("./sx"))^2)) , -1*(ch("./sx")-sin(90*(ch("./rz")/90-int(ch("./rz")/90))+135)*(sqrt(2*(.5*ch("./sx"))^2)))+ch("./sx")) + int(ch("./rz")/90)*-ch("./sx") Quote Link to comment Share on other sites More sharing options...
glyph Posted September 26, 2003 Share Posted September 26, 2003 wow krets, hot damn, that's cool I did the thing a few weeks ago but I got a tiny slippage which I couldnt fix mebbe I'll steal your code for a animated squashy version I wondered about.. Quote Link to comment Share on other sites More sharing options...
anakin78z Posted September 26, 2003 Author Share Posted September 26, 2003 here's my jello box Quote Link to comment Share on other sites More sharing options...
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