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Annotation of 43BSD/usr.lib/libplot/dumb/subr.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1980 Regents of the University of California.
                      3:  * All rights reserved.  The Berkeley software License Agreement
                      4:  * specifies the terms and conditions for redistribution.
                      5:  */
                      6: 
                      7: #ifndef lint
                      8: static char sccsid[] = "@(#)subr.c     5.1 (Berkeley) 5/7/85";
                      9: #endif not lint
                     10: 
                     11: #include "dumb.h"
                     12: 
                     13: /* Does not plot first point -- assumed that it is already plotted */
                     14: dda_line(ch, x0, y0, x1, y1)
                     15:        char ch;
                     16:        int x0, y0;     /* already transformed to screen coords */
                     17:        int x1, y1;     /* untransformed */
                     18: {
                     19:        int length, i;
                     20:        double deltaX, deltaY;
                     21:        double x, y;
                     22:        double floor();
                     23:        int abs();
                     24: 
                     25:        scale(x1, y1);
                     26: 
                     27:        length = abs(x1 - x0);
                     28:        if (abs(y1 -y0) > length)
                     29:                length = abs(y1 - y0);
                     30: 
                     31:        if (length == 0)
                     32:                return;
                     33: 
                     34:        deltaX = (double) (x1 - x0)/(double) length;
                     35:        deltaY = (double) (y1 - y0)/(double) length;
                     36: 
                     37:        x = (double) x0 + 0.5;
                     38:        y = (double) y0 + 0.5;
                     39: 
                     40:        for (i=0; i < length; ++i) {
                     41:                x += deltaX;
                     42:                y += deltaY;
                     43:                x0 = floor(x);
                     44:                y0 = floor(y);
                     45:                currentx = x0;
                     46:                currenty = y0;
                     47:                screenmat[currentx][currenty] = ch;
                     48:        }
                     49: }

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