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/* $Id: bresenhm.h,v 1.2 1996/09/15 14:18:10 brianp Exp $ */
/*
* Mesa 3-D graphics library
* Version: 2.0
* Copyright (C) 1995-1996 Brian Paul
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* $Log: bresenhm.h,v $
* Revision 1.2 1996/09/15 14:18:10 brianp
* now use GLframebuffer and GLvisual
*
* Revision 1.1 1996/09/13 01:38:16 brianp
* Initial revision
*
*/
/*
* A macro which executes Bresenham's line drawing algorithm. The
* previously defined BRESENHAM_PLOT macro is then used to 'plot' pixels.
*/
#ifndef BRESENHAM_H
#define BRESENHAM_H
#include "types.h"
/* TODO: combine these macros to make a linetemp.h file like tritemp.h */
/*
* Bresenham's line algorithm.
*/
#define BRESENHAM( x1, y1, x2, y2 ) \
{ \
GLint dx, dy, xf, yf, ta, tb, tt, i; \
if (x1!=x2 || y1!=y2) { \
if (x2>x1) { \
dx = x2-x1; \
xf = 1; \
} \
else { \
dx = x1-x2; \
xf = -1; \
} \
if (y2>y1) { \
dy = y2-y1; \
yf = 1; \
} \
else { \
dy = y1-y2; \
yf = -1; \
} \
if (dx>dy) { \
ta = dy+dy; \
tt = ta-dx; \
tb = tt-dx; \
for (i=0;i<=dx;i++) { \
BRESENHAM_PLOT( x1, y1 ) \
x1 += xf; \
if (tt<0) { \
tt += ta; \
} \
else { \
tt += tb; \
y1 += yf; \
} \
} \
} \
else { \
ta = dx+dx; \
tt = ta-dy; \
tb = tt-dy; \
for (i=0;i<=dy;i++) { \
BRESENHAM_PLOT( x1, y1 ) \
y1 += yf; \
if (tt<0) { \
tt += ta; \
} \
else { \
tt += tb; \
x1 += xf; \
} \
} \
} \
} \
}
/*
* Bresenham's line algorithm with Z interpolation.
* Z interpolation done with fixed point arithmetic, 8 fraction bits.
*/
#define BRESENHAM_Z( ctx, x1, y1, z1, x2, y2, z2 ) \
{ \
GLint dx, dy, xstep, ystep, ta, tb, tt, i; \
GLint dz, dzdx, dzdy; \
GLdepth *zptr; \
if (x1!=x2 || y1!=y2) { \
z1 = z1 << 8; \
z2 = z2 << 8; \
if (x2>x1) { \
dx = x2-x1; \
xstep = 1; \
dzdx = 1; \
} \
else { \
dx = x1-x2; \
xstep = -1; \
dzdx = -1; \
} \
if (y2>y1) { \
dy = y2-y1; \
ystep = 1; \
dzdy = ctx->Buffer->Width; \
} \
else { \
dy = y1-y2; \
ystep = -1; \
dzdy = -ctx->Buffer->Width; \
} \
zptr = Z_ADDRESS(ctx,x1,y1); \
if (dx>dy) { \
dz = (z2-z1)/dx; \
ta = dy+dy; \
tt = ta-dx; \
tb = tt-dx; \
for (i=0;i<=dx;i++) { \
GLdepth z = z1>>8; \
BRESENHAM_PLOT( x1, y1, z, zptr ) \
x1 += xstep; \
zptr += dzdx; \
if (tt<0) { \
tt += ta; \
} \
else { \
tt += tb; \
y1 += ystep; \
zptr += dzdy; \
} \
z1 += dz; \
} \
} \
else { \
dz = (z2-z1)/dy; \
ta = dx+dx; \
tt = ta-dy; \
tb = tt-dy; \
for (i=0;i<=dy;i++) { \
GLdepth z = z1>>8; \
BRESENHAM_PLOT( x1, y1, z, zptr ) \
y1 += ystep; \
zptr += dzdy; \
if (tt<0) { \
tt += ta; \
} \
else { \
tt += tb; \
x1 += xstep; \
zptr += dzdx; \
} \
z1 += dz; \
} \
} \
} \
}
extern GLuint gl_bresenham( GLcontext* ctx,
GLint x1, GLint y1, GLint x2, GLint y2,
GLint x[], GLint y[] );
extern GLuint gl_stippled_bresenham( GLcontext* ctx,
GLint x1, GLint y1, GLint x2, GLint y2,
GLint x[], GLint y[], GLubyte mask[] );
#endif
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