138 lines
3.9 KiB
C
138 lines
3.9 KiB
C
/*!
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\file Draw_Ellipse.c
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\author Mario Palomo <mpalomo@ihman.com>
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\author Jose M. de la Huerga Fernández
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\author Pepe González Mora
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\date 05-2002
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with this library; if not, write to the Free Foundation,
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Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#define SDL_DRAW_PUTPIXEL_BPP(A, B, C) \
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*(##A##(##B##(Uint8*)super->pixels + (y0+y)*super->pitch + \
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(x0+x)*SDL_DRAW_BPP)) = ##C##; \
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*(##A##(##B##(Uint8*)super->pixels + (y0-y)*super->pitch + \
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(x0+x)*SDL_DRAW_BPP)) = ##C##; \
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*(##A##(##B##(Uint8*)super->pixels + (y0+y)*super->pitch + \
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(x0-x)*SDL_DRAW_BPP)) = ##C##; \
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*(##A##(##B##(Uint8*)super->pixels + (y0-y)*super->pitch + \
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(x0-x)*SDL_DRAW_BPP)) = ##C##;
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#if SDL_DRAW_BPP == 1
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#define SDL_DRAW_PUTPIXEL SDL_DRAW_PUTPIXEL_BPP(0+,0+,color)
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#elif SDL_DRAW_BPP == 2
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#define SDL_DRAW_PUTPIXEL SDL_DRAW_PUTPIXEL_BPP((Uint16*),0+,color)
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#elif SDL_DRAW_BPP == 3
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#define SDL_DRAW_PUTPIXEL \
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SDL_DRAW_PUTPIXEL_BPP(0+,1+,colorbyte1) \
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if (SDL_BYTEORDER == SDL_BIG_ENDIAN) { \
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SDL_DRAW_PUTPIXEL_BPP(0+,0+,colorbyte2) \
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SDL_DRAW_PUTPIXEL_BPP(0+,2+,colorbyte0) \
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}else{ \
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SDL_DRAW_PUTPIXEL_BPP(0+,0+,colorbyte0) \
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SDL_DRAW_PUTPIXEL_BPP(0+,2+,colorbyte2) \
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}
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#elif SDL_DRAW_BPP == 4
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#define SDL_DRAW_PUTPIXEL SDL_DRAW_PUTPIXEL_BPP((Uint32*),0+,color)
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#endif /*SDL_DRAW_BPP*/
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void SDL_DRAWFUNCTION(SDL_Surface *super,
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Sint16 x0, Sint16 y0,
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Uint16 Xradius, Uint16 Yradius,
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Uint32 color)
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{
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Sint32 x, y;
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Sint32 Xchange, Ychange;
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Sint32 EllipseError;
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Sint32 TwoASquare, TwoBSquare;
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Sint32 StoppingX, StoppingY;
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#if SDL_DRAW_BPP == 3
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Uint8 colorbyte0 = (Uint8) (color & 0xff);
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Uint8 colorbyte1 = (Uint8) ((color >> 8) & 0xff);
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Uint8 colorbyte2 = (Uint8) ((color >> 16) & 0xff);
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#endif
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TwoASquare = 2*Xradius*Xradius;
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TwoBSquare = 2*Yradius*Yradius;
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/*1st set of points*/
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x = Xradius-1; /*radius zero == draw nothing*/
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y = 0;
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Xchange = Yradius*Yradius*(1-2*Xradius);
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Ychange = Xradius*Xradius;
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EllipseError = 0;
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StoppingX = TwoBSquare*Xradius;
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StoppingY = 0;
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/*Plot four ellipse points by iteration*/
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while (StoppingX > StoppingY) {
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SDL_DRAW_PUTPIXEL
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++y;
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StoppingY += TwoASquare;
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EllipseError += Ychange;
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Ychange += TwoASquare;
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if (( 2*EllipseError + Xchange) > 0) {
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--x;
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StoppingX -= TwoBSquare;
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EllipseError += Xchange;
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Xchange += TwoBSquare;
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}
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}/*while*/
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/*2nd set of points*/
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x = 0;
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y = Yradius-1; /*radius zero == draw nothing*/
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Xchange = Yradius*Yradius;
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Ychange = Xradius*Xradius*(1-2*Yradius);
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EllipseError = 0;
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StoppingX = 0;
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StoppingY = TwoASquare*Yradius;
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/*Plot four ellipse points by iteration*/
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while (StoppingX < StoppingY) {
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SDL_DRAW_PUTPIXEL
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++x;
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StoppingX += TwoBSquare;
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EllipseError += Xchange;
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Xchange += TwoBSquare;
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if ((2*EllipseError + Ychange) > 0) {
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--y;
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StoppingY -= TwoASquare;
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EllipseError += Ychange;
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Ychange += TwoASquare;
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}
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}
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}/*Draw_Ellipse*/
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#undef SDL_DRAW_PUTPIXEL
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#undef SDL_DRAW_PUTPIXEL_BPP
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