109 lines
2.8 KiB
C++
109 lines
2.8 KiB
C++
/* libsegl - Sebas Extended GL Library
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* Collection of Opengl/3D-Math helpers
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*
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* Copyright (c) 2008 by Sebastian Lohff, seba@seba-geek.de
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* http://www.seba-geek.de
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*
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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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*
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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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*
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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
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#include "sdlfuncs.h"
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namespace segl {
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Uint32 getPixel(SDL_Surface *surface, int x, int y)
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{
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int bpp = surface->format->BytesPerPixel;
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/* Here p is the address to the pixel we want to retrieve */
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Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;
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switch(bpp) {
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case 1:
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return *p;
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case 2:
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return *(Uint16 *)p;
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case 3:
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if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
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return p[0] << 16 | p[1] << 8 | p[2];
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else
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return p[0] | p[1] << 8 | p[2] << 16;
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case 4:
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return *(Uint32 *)p;
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default:
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return 0; /* shouldn't happen, but avoids warnings */
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}
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}
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void setPixel(SDL_Surface *surface, int x, int y, Uint32 pixel)
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{
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int bpp = surface->format->BytesPerPixel;
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/* Here p is the address to the pixel we want to set */
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Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;
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switch(bpp) {
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case 1:
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*p = pixel;
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break;
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case 2:
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*(Uint16 *)p = pixel;
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break;
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case 3:
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if(SDL_BYTEORDER == SDL_BIG_ENDIAN) {
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p[0] = (pixel >> 16) & 0xff;
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p[1] = (pixel >> 8) & 0xff;
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p[2] = pixel & 0xff;
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} else {
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p[0] = pixel & 0xff;
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p[1] = (pixel >> 8) & 0xff;
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p[2] = (pixel >> 16) & 0xff;
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}
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break;
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case 4:
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*(Uint32 *)p = pixel;
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break;
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}
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}
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void swapPixel(SDL_Surface *surface, int x1, int y1, int x2, int y2) {
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Uint32 a,b;
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a = getPixel(surface, x1, y1);
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b = getPixel(surface, x2, y2);
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setPixel(surface, x1, y1, b);
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setPixel(surface, x2, y2, a);
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}
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void mirrorSurfaceMiddleX(SDL_Surface *surface) {
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SDL_LockSurface(surface);
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int upto = surface->h / 2;
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for(int i=0; i<upto; i++) {
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for(int x=0; x<surface->w; x++) {
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swapPixel(surface, x, i, x, surface->h-1-i);
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}
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}
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SDL_UnlockSurface(surface);
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}
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} // namespace segl
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