# gdoc

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1. ## My approach to physics

I have uploaded updated files to the github. If someone wants to visit the grave -> https://github.com/michpolicht/gpx
2. ## My approach to physics

Thanks for advices.   I must honestly say that I am a little bit drunk while writing this post, so please forgive me errors and everything.   Madhogo! He/You have touched very interesting topic (btw it is not me who downoveted post).   Determinant was put there deliberately and with full consciousness! Once I had to write a program that draws multidimensionl cubes  (I have attached screenshot to give you better picture of what I am talking about). When I faced this problem I realize that rotation is actually performed on a plane, not around axis. Rotation around axis is an artificial being, which works only in 3 dimensions. Things are much more consistent and general if you use determinants. If you take a look at cross product you will find that out it consists of 3 determinants, one for each plane. You can describe rotations in 3 dimensions using determinants and this is IMO more natural, consistent and general than using cross product. In 2d you have one plane, in 3d you have 3 planes (although 2 are sufficient to rotate point to any position - I exploited this to limit number of sliders in my old Cube ?D program), in 4d you will have 6 planes (but again 3 are sufficent) and so on.   Moment of inertia on the other hand can be described by principal moments. So for 3 dimensional space it can be a 3-vector (x, y, z). If I will be able to expand my engine to 3d (or maybe even experiment with more dimensions...?) I will rather follow this path, because things seems to be much simplier. So this is why I am using determinant and real number, not because I limited myself to 2d, but paradoxically opposite, as from my earlier experiences it seems.   [attachment=15649:cube5d.png]   PS. A and B are not limited to (r, n),  (r, n, p) nor (r, n, p, L). They are ultimately numbers. In fact I was already exprimenting with soft bodies, but this is another chapter (leads to cool reminiscence of Mach's principle).
3. ## My approach to physics

Well, actually I have a working code that utilizes those equations... It still needs some polishing, but whole thing seems to work... I know how unrespectful numerics is :). I hope I will be able to do a major update of my project on sourceforge and maybe prepare some binaries for the public.   Thanks for the reply!
4. ## Collision resolution algorithm

This is possibly my solution to the problem: http://www.gamedev.net/topic/641608-my-approach-to-physics/
5. ## My approach to physics

Hi all.   The background of my story is that many years ago I was about to write a game based on the same idea as "Bad Piggies". I was coding in my spare time, thus development was slow and finally guys from Rovio overtook me. I'm not sure about the future of my game now, but if it is going to be abdandoned, then maybe it is a good idea to share some of my work.   Core component I was focused on was a physics engine. At the time I started to develop I was not happy with physics engines I had tested and I decided to write my own one. To my surprise literature was somewhat evasive (or maybe I searched not good enough) on aspects of dynamics I was interested in. For example I was not able to find how to deal with collisions of multuple bodies at multiple collision points or how to assure conservation of energy in the system after collision. I decided to derive formulas on my own. It was fun and I ended up with a bit of theory on which my engine could stand. A piece about collision handling was put into LaTeX and the resulting pdf is what I would like to share in this post. The rest depends on your feedback; I hope that your reaction will help me make further decisions.   Note: Project is hosted on sourceforge, but the code there is pretty old. Major update is waiting on my local drive, but I would like to hear opinions before moving on. I don't know if project makes any sense to anyone.   [attachment=14778:GPX_collisionHandling.pdf]   Paper was reviewed by my dog, so sorry for any kind of typos, bugs or bad grammar ;)