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Usenet 1994 January
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usenetsourcesnewsgroupsinfomagicjanuary1994.iso
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x
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volume8
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xfig2.8
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part03
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latex_line.c
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C/C++ Source or Header
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1990-07-02
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3KB
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155 lines
/*
* FIG : Facility for Interactive Generation of figures
*
* Copyright (c) 1985 by Supoj Sutanthavibul (supoj@sally.UTEXAS.EDU)
* January 1985.
* 1st revision : Aug 1985.
*
* %W% %G%
*/
#include "math.h"
int pgcd(a,b)
int a, b;
/*
* compute greatest common divisor, assuming 0 < a <= b
*/
{
b = b % a;
return (b)? gcd(b, a): a;
}
int gcd(a, b)
int a, b;
/*
* compute greatest common divisor
*/
{
if (a < 0) a = -a;
if (b < 0) b = -b;
return (a <= b)? pgcd(a, b): pgcd(b, a);
}
int lcm(a, b)
int a, b;
/*
* compute least common multiple
*/
{
return abs(a*b)/gcd(a,b);
}
double rad2deg = 57.295779513082320877;
struct angle_table {
int x, y;
double angle;
};
struct angle_table line_angles[25] =
{ {0, 1, 90.0},
{1, 0, 0.0},
{1, 1, 45.0},
{1, 2, 63.434948822922010648},
{1, 3, 71.565051177077989351},
{1, 4, 75.963756532073521417},
{1, 5, 78.690067525979786913},
{1, 6, 80.537677791974382609},
{2, 1, 26.565051177077989351},
{2, 3, 56.309932474020213086},
{2, 5, 68.198590513648188229},
{3, 1, 18.434948822922010648},
{3, 2, 33.690067525979786913},
{3, 4, 53.130102354155978703},
{3, 5, 59.036243467926478582},
{4, 1, 14.036243467926478588},
{4, 3, 36.869897645844021297},
{4, 5, 51.340191745909909396},
{5, 1, 11.309932474020213086},
{5, 2, 21.801409486351811770},
{5, 3, 30.963756532073521417},
{5, 4, 38.659808254090090604},
{5, 6, 50.194428907734805993},
{6, 1, 9.4623222080256173906},
{6, 5, 39.805571092265194006}
};
struct angle_table arrow_angles[13] =
{ {0, 1, 90.0},
{1, 0, 0.0},
{1, 1, 45.0},
{1, 2, 63.434948822922010648},
{1, 3, 71.565051177077989351},
{1, 4, 75.963756532073521417},
{2, 1, 26.565051177077989351},
{2, 3, 56.309932474020213086},
{3, 1, 18.434948822922010648},
{3, 2, 33.690067525979786913},
{3, 4, 53.130102354155978703},
{4, 1, 14.036243467926478588},
{4, 3, 36.869897645844021297},
};
get_slope(dx, dy, sxp, syp, arrow)
int dx, dy, *sxp, *syp, arrow;
{
double angle;
int i, s, max;
double d, d1;
struct angle_table *st;
if (dx == 0) {
*sxp = 0;
*syp = (dy < 0)? -1: 1;
return;
}
angle = atan((double)abs(dy) / (double)abs(dx)) * rad2deg;
if (arrow) {
st = arrow_angles;
max = 13;
} else {
st = line_angles;
max = 25;
}
s = 0;
d = 9.9e9;
for (i = 0; i < max; i++) {
d1 = fabs(angle - st[i].angle);
if (d1 < d) {
s = i;
d = d1;
}
}
*sxp = st[s].x;
if (dx < 0) *sxp = -*sxp;
*syp = st[s].y;
if (dy < 0) *syp = -*syp;
}
latex_endpoint(x1, y1, x2, y2, xout, yout, arrow, magnet)
int x1, y1, x2, y2;
int *xout, *yout;
int arrow, magnet;
{
int dx, dy, sx, sy, ds, dsx, dsy;
dx = x2-x1;
dy = y2-y1;
get_slope(dx, dy, &sx, &sy, arrow);
if (abs(sx) >= abs(sy)) {
ds = lcm(sx, magnet*gcd(sx,magnet));
dsx = (2*abs(dx)/ds + 1)/2;
dsx = (dx >= 0)? dsx*ds: -dsx*ds;
*xout = x1 + dsx;
*yout = y1 + dsx*sy/sx;
} else {
ds = lcm(sy, magnet*gcd(sy,magnet));
dsy = (2*abs(dy)/ds + 1)/2;
dsy = (dy >= 0)? dsy*ds: -dsy*ds;
*yout = y1 + dsy;
*xout = x1 + dsy*sx/sy;
}
}