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