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/* This file is part of the GNU libxmi package.
Copyright (C) 1985, 1986, 1987, 1988, 1989, X Consortium. For an
associated permission notice, see the accompanying file README-X.
GNU enhancements Copyright (C) 1998, 1999, 2000, 2005, Free Software
Foundation, Inc.
The GNU libxmi package is free software. You may redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software foundation; either version 2, or (at your
option) any later version.
The GNU libxmi package 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
General Public License for more details.
You should have received a copy of the GNU General Public License along
with the GNU plotutils package; see the file COPYING. If not, write to
the Free Software Foundation, Inc., 51 Franklin St., Fifth Floor,
Boston, MA 02110-1301, USA. */
#include "sys-defines.h"
#include "extern.h"
#include "xmi.h"
#include "mi_spans.h"
#include "mi_gc.h"
#include "mi_api.h"
#include "mi_scanfill.h"
/* forward references */
static int getPolyYBounds (const miPoint *pts, int n, int *by, int *ty);
/*
* Written by Brian Kelleher; Dec. 1985.
* Hacked by Robert S. Maier, 1998-99.
*
* Fill a convex polygon (if the polygon is not convex then the result is
* undefined). The algorithm is to order the edges from smallest y to
* largest y, by partitioning the array into a left edge list and a right
* edge list. The algorithm used to traverse each edge is an extension of
* Bresenham's midpoint line algorithm, with y as the major axis.
*
* All painting goes through the low-level MI_PAINT_SPANS() macro.
*
* See mi_plygen.c for miFillGeneralPoly(), a slower routine that can fill
* general polygons (i.e. polygons that may be non-convex or
* self-intersecting). */
/* ARGS: pGC = unused */
void
miFillConvexPoly (miPaintedSet *paintedSet, const miGC *pGC, int count, const miPoint *ptsIn)
/* count = num of points, ptsIn = the points */
{
int xl = 0, xr = 0; /* x vals of left and right edges */
int dl = 0, dr = 0; /* decision variables */
int ml = 0, m1l = 0; /* left edge slope and slope+1 */
int mr = 0, m1r = 0; /* right edge slope and slope+1 */
int incr1l = 0, incr2l = 0; /* left edge error increments */
int incr1r = 0, incr2r = 0; /* right edge error increments */
int dy; /* delta y */
int y; /* current scanline */
int left, right; /* indices to first endpoints */
int i; /* loop counter */
int nextleft, nextright; /* indices to second endpoints */
miPoint *ptsOut, *FirstPoint; /* output buffer */
unsigned int *width, *FirstWidth; /* output buffer */
int imin; /* index of smallest vertex (in y) */
int ymin; /* y-extents of polygon */
int ymax;
/*
* find leftx, bottomy, rightx, topy, and the index
* of bottomy. Also translate the points.
*/
imin = getPolyYBounds(ptsIn, count, &ymin, &ymax);
dy = ymax - ymin + 1;
if ((count < 3) || (dy < 0))
return;
ptsOut = FirstPoint = (miPoint *)mi_xmalloc(sizeof(miPoint) * dy);
width = FirstWidth = (unsigned int *)mi_xmalloc(sizeof(unsigned int) * dy);
nextleft = nextright = imin;
y = ptsIn[nextleft].y;
/*
* loop through all edges of the polygon
*/
do {
/*
* add a left edge if we need to
*/
if (ptsIn[nextleft].y == y)
{
left = nextleft;
/*
* find the next edge, considering the end
* conditions of the array.
*/
nextleft++;
if (nextleft >= count)
nextleft = 0;
/*
* now compute all of the random information
* needed to run the iterative algorithm.
*/
BRESINITPGON(ptsIn[nextleft].y-ptsIn[left].y,
ptsIn[left].x,ptsIn[nextleft].x,
xl, dl, ml, m1l, incr1l, incr2l);
}
/*
* add a right edge if we need to
*/
if (ptsIn[nextright].y == y)
{
right = nextright;
/*
* find the next edge, considering the end
* conditions of the array.
*/
nextright--;
if (nextright < 0)
nextright = count-1;
/*
* now compute all of the random information
* needed to run the iterative algorithm.
*/
BRESINITPGON(ptsIn[nextright].y-ptsIn[right].y,
ptsIn[right].x,ptsIn[nextright].x,
xr, dr, mr, m1r, incr1r, incr2r);
}
/*
* generate scans to fill while we still have
* a right edge as well as a left edge.
*/
i = IMIN(ptsIn[nextleft].y, ptsIn[nextright].y) - y;
/* in case we're called with non-convex polygon */
if(i < 0)
{
free (FirstWidth);
free (FirstPoint);
return;
}
while (i-- > 0)
{
ptsOut->y = y;
/*
* reverse the edges if necessary
*/
if (xl < xr)
{
*(width++) = (unsigned int)(xr - xl);
(ptsOut++)->x = xl;
}
else
{
*(width++) = (unsigned int)(xl - xr);
(ptsOut++)->x = xr;
}
y++;
/* increment down the edges */
BRESINCRPGON(dl, xl, ml, m1l, incr1l, incr2l);
BRESINCRPGON(dr, xr, mr, m1r, incr1r, incr2r);
}
} while (y != ymax);
/*
* Finally, paint the <remaining> spans
*/
MI_PAINT_SPANS(paintedSet, pGC->pixels[1], ptsOut - FirstPoint, FirstPoint, FirstWidth)
}
/*
* Find the index of the point with the smallest y.
*/
static int
getPolyYBounds (const miPoint *pts, int n, int *by, int *ty)
{
const miPoint *ptsStart = pts;
const miPoint *ptMin;
int ymin, ymax;
ptMin = pts;
ymin = ymax = (pts++)->y;
while (--n > 0)
{
if (pts->y < ymin)
{
ptMin = pts;
ymin = pts->y;
}
if(pts->y > ymax)
ymax = pts->y;
pts++;
}
*by = ymin;
*ty = ymax;
return (ptMin - ptsStart);
}
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