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66 lines
1.4 KiB
C
66 lines
1.4 KiB
C
/* ------------------------------------------------------------------------
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System : Manx Aztec C65 Version 3.2b
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MS-DOS cross-development environment
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Platform : Apple IIe 128K PRODOS 8
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Program : d2line.c
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Description : G2 Library Routine
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Double Hi-Res 140 x 192 x 16 color
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Bresenham Algorithm line drawing routine
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for ProDOS 8 Sys Programs
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Uses Page 2 Double Hi-Res to avoid
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ProDOS Sys Program Load Address at 0x2000
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Written by : Bill Buckels
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Date Written : February 2013
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Revision : 1.0 First Release
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Licence : You may use this code for whatever you wish as long
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as you agree that Bill Buckels has no warranty or
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liability obligations whatsoever from said use.
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------------------------------------------------------------------------ */
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d2line(x1, y1, x2, y2, drawcolor)
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int x1, y1, x2, y2, drawcolor;
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{
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int dx, dy, sx, sy, err, err2;
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if(x1 < x2) {
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dx = x2 - x1;
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sx = 1;
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}
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else {
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sx = -1;
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dx = x1 - x2;
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}
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if(y1 < y2) {
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sy = 1;
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dy = y2 - y1;
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}
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else {
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sy = -1;
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dy = y1 - y2;
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}
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err = dx-dy;
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for (;;) {
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d2plot(x1,y1,drawcolor);
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if(x1 == x2 && y1 == y2)break;
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err2 = err*2;
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if(err2 > (0-dy)) {
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err = err - dy;
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x1 = x1 + sx;
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}
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if(err2 < dx) {
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err = err + dx;
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y1 = y1 + sy;
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}
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}
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return;
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}
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