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Path: ...!weretis.net!feeder9.news.weretis.net!news.nk.ca!rocksolid2!i2pn2.org!.POSTED!not-for-mail From: fir <profesor.fir@gmail.com> Newsgroups: comp.lang.c Subject: Re: [prog. in c] how to make stable paricles Date: Tue, 12 Nov 2024 22:41:10 +0100 Organization: i2pn2 (i2pn.org) Message-ID: <369b7df8c9cbb5f1d94a34df1a30b649e79b2bd9@i2pn2.org> References: <86afdace41e07eca9975d9c425207fcb89d70073@i2pn2.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Tue, 12 Nov 2024 21:41:12 -0000 (UTC) Injection-Info: i2pn2.org; logging-data="2177302"; mail-complaints-to="usenet@i2pn2.org"; posting-account="+ydHcGjgSeBt3Wz3WTfKefUptpAWaXduqfw5xdfsuS0"; User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:91.0) Gecko/20100101 Firefox/91.0 SeaMonkey/2.53.19 X-Spam-Checker-Version: SpamAssassin 4.0.0 In-Reply-To: <86afdace41e07eca9975d9c425207fcb89d70073@i2pn2.org> Bytes: 4230 Lines: 84 fir pisze: > see that simulation > > https://www.youtube.com/watch?v=pP-uCjLp3RY > > there is a group of lights/dots/balls/points (say atoms) and such fotces > are applied > 1) if the ball is into wall apply a force proportional to depth of > being into wall > > point[i].vx -= H* wall_penetration_x ; > point[i].vy -= H* wall_penetration_y ; > > 2) if the ball is to much close to other ball same the force related to > depth of penetration is applied (though here its square) > > > point[i].vx+= (dx/dist)* (n_pen*B)*(n_pen*B) /point[i].mass ; > point[i].vy+= (dy/dist)* (n_pen*B)*(n_pen*B) /point[i].mass ; > > > i chose it partially conceptually - knowing a=F/m - and partially > experimantally..it work wery well imo > > the problem is i want to apply some ball-ball force additional to > this repeling one that would make those ball build in a kinda multi-ball > relativly stable "particles" ... and the question is what this force > should be? > > here above on this video the lines you see are drawed when this third > force start to work.. (so teh lines arre kinda optical debug showing > how it work) i applied some but the particles that forms are much to > dynamical, oscilate llike crazy then sometimas shot one of atoms out and > so on > > and i need a stable one > > i experimented with this additional link force but not much > what i experimented was like adding link it is attraction force > that enebles when two points are closer than 1.5*link distance, which is > 20 units (pixels) it is this attract force work on distance closer than > 30 pixels > > the force is something like > > double link_dist = 20; > double dx = point[i].x - point[n].x; > double dy = point[i].y - point[n].y; > double Mi = point[i].mass; > > double dist = sqrt(dx*dx + dy*dy ); > > if(dist>link_dist*1.5) return; > > double L = 1.; > double p = (dist - link_dist)*L; > > point[i].vx+= -(dx/dist)*(p*p)*sign(p)/point[i].mass; > point[i].vy+= -(dy/dist)*(p*p)*sign(p)/point[i].mass; > > if(!m_toggler) > DrawLine2d(point[i].x, point[i].y, point[n].x, point[n].y,0xffffff ); > > but as i said the results are to messy and i need stable little "solid > bodies" i mean more "stiff" particles > > some ideas as to what this link force should be? note as to "stiff" particles (not sure as to this word becouse weak english) they are possible as check some of my old demo https://www.youtube.com/watch?v=0bw_R8nIIG4 this 9 dot "Rectangle" is made by simple 1-1 link forces but the difference is i set up those initial distances like 100 and sqrt (100) = 141.42 and so on by hand from init function in code and this is very tiresome to set upo by hand so i think it would be give some force that works liek chemistry it is glues that balls together naturall way not by tedious set up - but its the proof that it is generaly possible to have stiff particles (more to say its making like rotating objests with angular momentum without any code of angular momentum just simple lineas bal-ball forces and newtonian a=F/m)