# cluelessWanderer

Member

4

111 Neutral

• Rank
Newbie
1. ## Dynamic friction 2D rigid body

I've looked at Chris heckers columns on rigid body physics and was able to implement a frictionless rigid body simulation,however, now I'm looking to implement dynamic friction.Unfortunately there doesn't seem to be alot of information available on how to achieve this on the net or maybe I haven't been looking hard enough. In any case I've come here to ask for assistance on how to achieve dynamic friction in my 2D rigid body simulation. Here's a temporary clip of what the simulation looks like currently: https://www.youtube.com/watch?v=OgBbqDXONQM
2. ## SPH paper...notation issues.

So i was reading an sph paper(link: [url="http://www.matthiasmueller.info/publications/sca03.pdf"]http://www.matthiasm...tions/sca03.pdf[/url]) and everything was going well untill i reached the equations for the smoothing kernel. --The image of the equation is an attachment. Appearently i can't link images from imageShack.-- I've never seen piecewise functions like this before. So bolded "r" is supposedly a displacement vector and "h" is the support radius( a scalar). This begs the question,what is the unbolded r in this equation? The distance? So assuming r is the distance between two particles... If r is between 0 and the support radius "h" i compute (h^2 - r^2)^3 and then multiply that value by (315 / 64*pi*h^9) ? Also the paper doesnt give the gradients for the smoothing kernels so i guess i have to take them myself(assuming the del operator is the gradient in this paper)? after looking back at the article im confused to what the del operator actually does. If you refer to eqn (15) the right hand side of that equation evaluates to a scalar. right? If thats true then how does a scalar become a vector after the del operator is used(eqn 16)?
3. ## saving levels/maps/game infomation in general

[quote name='Cornstalks' timestamp='1337655181' post='4942068'] The simplest way would be using something like [url="http://icculus.org/physfs/"]PhysicsFS[/url]. Beyond that, it's a significant amount of work writing your own IO serialization/packing library. It's easy to write something out to a binary file, and it's easy to read it in, and it's not too complicated to just smash a bunch of files together into one big file. The significant amount of work comes from making changes to this big file. What if you want to change that .bmp or map file, or add or remove something? There are several ways to handle this, but if you don't do it right, it can be a huge pain in the butt. [url="http://www.gamedev.net/topic/622754-are-pack-files-pak-zip-wad-etc-worth-it/"]I started a thread about this[/url] awhile ago, you may be interested in some of the replies. [/quote] Thank you for your response. And for recomending this library it looks like it can help me achive my goals without alot of headache.
4. ## saving levels/maps/game infomation in general

So i've been trying to make this 2D game engine with opengl and SDL. Right now i've got basic physics down (its kind of like rigid body physics but not quite) ,Particle fluid(from that paper 'particle-based viscoelastic fluid simulation'), and soft Edged shadows. Anyway whats been bothering me for a while now was how im going to save all the information. I want to be able to store all the editor's resources in one big file. But i have no idea how to do this. The most i can do with binary files is read and write numbers. So it was easy for me to save the geometry of the level. I have no idea how im going to store multiple .bmps .jpegs into one file. Can someone shed some light on my issue?