proxy70

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv=Content-Type content="text/html; charset=utf8">
<title>/usr/web/sources/contrib/aiju/mole1.c - Plan 9 from Bell Labs</title>
<!-- THIS FILE IS AUTOMATICALLY GENERATED. -->
<!-- EDIT sources.tr INSTEAD. -->
</meta>
</head>
<body>
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: center;">
<span style="font-size: 10pt"><a href="/plan9/">Plan 9 from Bell Labs</a>&rsquo;s /usr/web/sources/contrib/aiju/mole1.c</span></p>
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
<center><font size=-1>
Copyright © 2009 Alcatel-Lucent.<br />
Distributed under the
<a href="/plan9/license.html">Lucent Public License version 1.02</a>.
<br />
<a href="/plan9/download.html">Download the Plan 9 distribution.</a>
</font>
</center>
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
<table width="100%" cellspacing=0 border=0><tr><td align="center">
<table cellspacing=0 cellpadding=5 bgcolor="#eeeeff"><tr><td align="left">
<pre>
<!-- END HEADER -->
#include &lt;u.h&gt;
#include &lt;libc.h&gt;
#include &lt;draw.h&gt;
#include &lt;event.h&gt;

enum {N = 20};

#define dt 0.01
#define xmin -40
#define xmax 40
#define ymin -40
#define ymax 40
#define v0 0.2
#define mini(a,b) (((a)&lt;(b))?(a):(b))

typedef struct Particle Particle;
struct Particle {
	double x, y;
	double vx, vy;
	double ax, ay;
	double prevx, prevy;
	Image* col;
};

int colors[] = {
              DBlack,
              DRed,
              DGreen,
              DBlue,
              DCyan,
              DMagenta,
              DDarkyellow,
              DDarkgreen,
              DPalegreen,
              DMedgreen,
              DDarkblue,
              DPalebluegreen,
              DPaleblue,
              DBluegreen,
              DGreygreen,
              DPalegreygreen,
              DYellowgreen,
              DMedblue,
              DGreyblue,
              DPalegreyblue,
              DPurpleblue
};

Particle A[N], B[N];
Particle *prev = A, *cur = B;

void
reset(void)
{
	int j, grid = sqrt(N)+0.5;
	Particle *p;
	draw(screen, screen-&gt;r, display-&gt;white, 0, ZP);
	for(j=0;j&lt;N;j++) {
		p = prev+j;
		p-&gt;x = 2*(j%grid)+frand()/2;
		p-&gt;y = 2*(j/grid)+frand()/2;
		p-&gt;vx = 1.*v0*frand();
		p-&gt;vy = 1.*v0*frand();
		p-&gt;prevx = p-&gt;x - p-&gt;vx * dt;
		p-&gt;prevy = p-&gt;y - p-&gt;vy * dt;
		p-&gt;col = allocimage(display, Rect(0,0,1,1), RGB24, 1, colors[rand()%(sizeof(colors)/sizeof(int))]);
		if(!p-&gt;col) sysfatal("allocimage");
	}
}

void
main()
{
	srand(time(0));
	initdraw(0, 0, "Molecular Dynamics");
	einit(Emouse | Ekeyboard);
	
	int j;
	Particle *p, *q;
	double dx, dy, R, F;

	reset();

	while(1) {
		memset(cur, 0, sizeof(Particle) * N);
		for(p=prev;p&lt;prev+N;p++) {
			for(q=prev;q&lt;p;q++) {
				dx = p-&gt;x - q-&gt;x;
				dy = p-&gt;y - q-&gt;y;
				R = dx*dx + dy*dy;
				if(R &gt;= 9) continue;
				R = 1/sqrt(R);
				double R2, R4, R6, R12;
				R2 = R * R;
				R4 = R2 * R2;
				R6 = R4 * R2;
				R12 = R6 * R6;
				F = 24*(2*R12 - R6);
				dx *= F;
				dy *= F;
				(p-prev+cur)-&gt;ax += dx;
				(p-prev+cur)-&gt;ay += dy;
				(q-prev+cur)-&gt;ax -= dx;
				(q-prev+cur)-&gt;ay -= dy;
			}
		}
		for(j=0;j&lt;N;j++) {
			int x, y;
			p = prev+j;
			q = cur+j;
			q-&gt;x = 2*p-&gt;x - p-&gt;prevx + q-&gt;ax * dt*dt;
			q-&gt;y = 2*p-&gt;y - p-&gt;prevy + q-&gt;ay * dt*dt;
			q-&gt;vx = (q-&gt;x - p-&gt;prevx) / (2*dt);
			q-&gt;vy = (q-&gt;y - p-&gt;prevy) / (2*dt);
			q-&gt;prevx = p-&gt;x;
			q-&gt;prevy = p-&gt;y;
			q-&gt;col = p-&gt;col;
			x = (screen-&gt;r.max.x - screen-&gt;r.min.x) * (q-&gt;x - xmin) / (xmax - xmin) + screen-&gt;r.min.x;
			y = (screen-&gt;r.max.y - screen-&gt;r.min.y) * (q-&gt;y - ymin) / (ymax - ymin) + screen-&gt;r.min.y;
			draw(screen, Rect(x, y, x+1, y+1), p-&gt;col, 0, ZP);
		}

		Particle* tmp = prev;
		prev = cur;
		cur = tmp;
		flushimage(display, 0);
		
		if(ecankbd()) {
			switch(ekbd()) {
				case 'q': exits(0); break;
				case 'r': reset(); break;
				case 'f': draw(screen, screen-&gt;r, display-&gt;white, 0, ZP); break;
			}
		}
	}
}

void
eresized(int new)
{
	if(new) getwindow(display, Refnone);
}
<!-- BEGIN TAIL -->
</pre>
</td></tr></table>
</td></tr></table>
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: center;">
<span style="font-size: 10pt"></span></p>
<p style="margin-top: 0; margin-bottom: 0.50in"></p>
<p style="margin-top: 0; margin-bottom: 0.33in"></p>
<center><table border="0"><tr>
<td valign="middle"><a href="http://www.alcatel-lucent.com/"><img border="0" src="/plan9/img/logo_ft.gif" alt="Bell Labs" />
</a></td>
<td valign="middle"><a href="http://www.opensource.org"><img border="0" alt="OSI certified" src="/plan9/img/osi-certified-60x50.gif" />
</a></td>
<td><img style="padding-right: 45px;" alt="Powered by Plan 9" src="/plan9/img/power36.gif" />
</td>
</tr></table></center>
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
<center>
<span style="font-size: 10pt">(<a href="/plan9/">Return to Plan 9 Home Page</a>)</span>
</center>
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
<center><font size=-1>
<span style="font-size: 10pt"><a href="http://www.lucent.com/copyright.html">Copyright</a></span>
<span style="font-size: 10pt">© 2009 Alcatel-Lucent.</span>
<span style="font-size: 10pt">All Rights Reserved.</span>
<br />
<span style="font-size: 10pt">Comments to</span>
<span style="font-size: 10pt"><a href="mailto:webmaster@plan9.bell-labs.com">webmaster@plan9.bell-labs.com</a>.</span>
</font></center>
</body>
</html>