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fixed diag lines - initial error for bresnham algo should be 1/2 max error, not 0.

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svn path=/trunk/; revision=5522
This commit is contained in:
Royce Mitchell III 2003-08-11 04:23:37 +00:00
parent 08f2d72ce1
commit 111ed4cd20
1 changed files with 15 additions and 15 deletions
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30
reactos/drivers/dd/vga/display/objects/lineto.c
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@ -16,7 +16,7 @@
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id: lineto.c,v 1.14 2003/08/11 04:02:07 royce Exp $
* $Id: lineto.c,v 1.15 2003/08/11 04:23:37 royce Exp $
*/
#include "../vgaddi.h"
@ -41,7 +41,7 @@ vgaNWtoSE(PCLIPOBJ Clip, PBRUSHOBJ Brush, LONG x, LONG y, LONG deltax, LONG delt
ClipRect = RectEnum.arcl;
delta = max(deltax, deltay);
i = 0;
error = 0;
error = delta/2;
while (i < delta && (ClipRect < RectEnum.arcl + RectEnum.c || EnumMore))
{
while ((ClipRect < RectEnum.arcl + RectEnum.c /* there's still a current clip rect */
@ -60,30 +60,30 @@ vgaNWtoSE(PCLIPOBJ Clip, PBRUSHOBJ Brush, LONG x, LONG y, LONG deltax, LONG delt
ClipRect++;
}
}
if (ClipRect < RectEnum.arcl + RectEnum.c) /* If there's no current clip rect we're done */
if ( ClipRect < RectEnum.arcl + RectEnum.c ) /* If there's no current clip rect we're done */
{
if (ClipRect->left <= x && ClipRect->top <= y)
{
vgaPutPixel(x, y, Pixel);
vgaPutPixel ( x, y, Pixel );
}
if (deltax < deltay)
if ( deltax < deltay )
{
y++;
error = error + deltax;
if (deltay <= error)
error += deltax;
if ( error >= deltay )
{
x++;
error = error - deltay;
error -= deltay;
}
}
else
{
x++;
error = error + deltay;
if (deltax <= error)
error += deltay;
if ( error >= deltax )
{
y++;
error = error - deltax;
y++;
error -= deltax;
}
}
i++;
@ -107,7 +107,7 @@ vgaSWtoNE(PCLIPOBJ Clip, PBRUSHOBJ Brush, LONG x, LONG y, LONG deltax, LONG delt
ClipRect = RectEnum.arcl;
delta = max(deltax, deltay);
i = 0;
error = 0;
error = delta/2;
while (i < delta && (ClipRect < RectEnum.arcl + RectEnum.c || EnumMore))
{
while ((ClipRect < RectEnum.arcl + RectEnum.c
@ -172,7 +172,7 @@ vgaNEtoSW(PCLIPOBJ Clip, PBRUSHOBJ Brush, LONG x, LONG y, LONG deltax, LONG delt
ClipRect = RectEnum.arcl;
delta = max(deltax, deltay);
i = 0;
error = 0;
error = delta/2;
while (i < delta && (ClipRect < RectEnum.arcl + RectEnum.c || EnumMore))
{
while ((ClipRect < RectEnum.arcl + RectEnum.c
@ -237,7 +237,7 @@ vgaSEtoNW(PCLIPOBJ Clip, PBRUSHOBJ Brush, LONG x, LONG y, LONG deltax, LONG delt
ClipRect = RectEnum.arcl;
delta = max(deltax, deltay);
i = 0;
error = 0;
error = delta/2;
while (i < delta && (ClipRect < RectEnum.arcl + RectEnum.c || EnumMore))
{
while ((ClipRect < RectEnum.arcl + RectEnum.c