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killed a rounding error in line clipping 

SVN revision: 3308
This commit is contained in:
Tom Gilbert 2000-09-03 22:43:59 +00:00
parent 6a4d800e92
commit cdf8e6ed76
1 changed files with 35 additions and 20 deletions
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55
src/rgbadraw.c
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@ -1,4 +1,5 @@
#include <X11/Xlib.h>
#include <math.h>
#include "common.h"
#include "colormod.h"
#include "image.h"
@ -14,6 +15,8 @@
#define MAX(a,b) (((a) > (b)) ? (a) : (b))
#define round(a) floor(a+0.5)
void
__imlib_FlipImageHoriz(ImlibImage * im)
{
@ -1552,9 +1555,15 @@ imlib_clip_line(int x0, int y0, int x1, int y1, int xmin, int xmax, int ymin,
{
ImlibOutCode outcode0, outcode1, outcode_out;
unsigned char accept = FALSE, done = FALSE;
double dx0, dy0, dx1, dy1;
outcode0 = __imlib_comp_outcode(x0, y0, xmin, xmax, ymin, ymax);
outcode1 = __imlib_comp_outcode(x1, y1, xmin, xmax, ymin, ymax);
dx0 = x0;
dx1 = x1;
dy0 = y0;
dy1 = y1;
outcode0 = __imlib_comp_outcode(dx0, dy0, xmin, xmax, ymin, ymax);
outcode1 = __imlib_comp_outcode(dx1, dy1, xmin, xmax, ymin, ymax);
do
{
@ -1572,50 +1581,57 @@ imlib_clip_line(int x0, int y0, int x1, int y1, int xmin, int xmax, int ymin,
outcode_out = outcode0 ? outcode0 : outcode1;
if (outcode_out & TOP)
{
x = x0 + (x1 - x0) * (ymax - y0) / (y1 - y0);
x = dx0 + (dx1 - dx0) * ((double) ymax - dy0) / (dy1 - dy0);
y = ymax;
}
else if (outcode_out & BOTTOM)
{
x = x0 + (x1 - x0) * (ymin - y0) / (y1 - y0);
x = dx0 + (dx1 - dx0) * ((double) ymin - dy0) / (dy1 - dy0);
y = ymin;
}
else if (outcode_out & RIGHT)
{
y = y0 + (y1 - y0) * (xmax - x0) / (x1 - x0);
y = dy0 + (dy1 - dy0) * ((double) xmax - dx0) / (dx1 - dx0);
x = xmax;
}
else
{
y = y0 + (y1 - y0) * (xmin - x0) / (x1 - x0);
y = dy0 + (dy1 - dy0) * ((double) xmin - dx0) / (dx1 - dx0);
x = xmin;
}
if (outcode_out == outcode0)
{
x0 = x;
y0 = y;
outcode0 = __imlib_comp_outcode(x0, y0, xmin, xmax, ymin, ymax);
dx0 = x;
dy0 = y;
outcode0 = __imlib_comp_outcode(dx0, dy0, xmin, xmax, ymin, ymax);
}
else
{
x1 = x;
y1 = y;
outcode1 = __imlib_comp_outcode(x1, y1, xmin, xmax, ymin, ymax);
dx1 = x;
dy1 = y;
outcode1 = __imlib_comp_outcode(dx1, dy1, xmin, xmax, ymin, ymax);
}
}
}
while (done == FALSE);
*clip_x0 = x0;
*clip_y0 = y0;
*clip_x1 = x1;
*clip_y1 = y1;
/* round up before converting down to ints */
dx0 = round(dx0);
dx1 = round(dx1);
dy0 = round(dy0);
dy1 = round(dy1);
*clip_x0 = dx0;
*clip_y0 = dy0;
*clip_x1 = dx1;
*clip_y1 = dy1;
return accept;
}
ImlibOutCode __imlib_comp_outcode(double x, double y, double xmin,
double xmax, double ymin, double ymax)
ImlibOutCode
__imlib_comp_outcode(double x, double y, double xmin, double xmax,
double ymin, double ymax)
{
ImlibOutCode code = 0;
@ -1630,8 +1646,7 @@ ImlibOutCode __imlib_comp_outcode(double x, double y, double xmin,
return code;
}
ImlibPoly
__imlib_polygon_new()
ImlibPoly __imlib_polygon_new()
{
ImlibPoly poly;