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109
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1 #include <iostream>
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2 #include <SDL.h>
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3 #include <SDL_opengl.h>
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4 #include <SDL_image.h>
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5 #include <libxml/parser.h>
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6 using namespace std;
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7
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8 int power_of_two(int input)
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9 {
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10 int value = 1;
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11
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12 while ( value < input )
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13 {
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14 value <<= 1;
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15 }
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16 return value;
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17 }
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18
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19 GLuint SDL_GL_LoadTexture(SDL_Surface *surface, GLfloat *texcoord)
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20 {
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21 GLuint texture;
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22 int w, h;
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23 SDL_Surface *image;
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24 SDL_Rect area;
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25 Uint32 saved_flags;
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26 Uint8 saved_alpha;
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27
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28 /* Use the surface width and height expanded to powers of 2 */
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29 w = power_of_two(surface->w);
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30 h = power_of_two(surface->h);
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31 texcoord[0] = 0.0f; /* Min X */
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32 texcoord[1] = 0.0f; /* Min Y */
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33 texcoord[2] = (GLfloat)surface->w / w; /* Max X */
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34 texcoord[3] = (GLfloat)surface->h / h; /* Max Y */
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35
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36 image = SDL_CreateRGBSurface(
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37 SDL_SWSURFACE,
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38 w, h,
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39 32,
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40 #if SDL_BYTEORDER == SDL_LIL_ENDIAN /* OpenGL RGBA masks */
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41 0x000000FF,
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42 0x0000FF00,
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43 0x00FF0000,
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44 0xFF000000
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45 #else
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46 0xFF000000,
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47 0x00FF0000,
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48 0x0000FF00,
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49 0x000000FF
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50 #endif
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51 );
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52 if ( image == NULL )
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53 {
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54 return 0;
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55 }
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56
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57 /* Save the alpha blending attributes */
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58 saved_flags = surface->flags&(SDL_SRCALPHA|SDL_RLEACCELOK);
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59 saved_alpha = surface->format->alpha;
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60 if ( (saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA )
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61 {
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62 SDL_SetAlpha(surface, 0, 0);
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63 }
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64 /* Copy the surface into the GL texture image */
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65 area.x = 0;
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66 area.y = 0;
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67 area.w = surface->w;
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68 area.h = surface->h;
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69 SDL_BlitSurface(surface, &area, image, &area);
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70
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71 /* Restore the alpha blending attributes */
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72 if ( (saved_flags & SDL_SRCALPHA) == SDL_SRCALPHA )
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73 {
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74 SDL_SetAlpha(surface, saved_flags, saved_alpha);
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75 }
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76
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77 /* Create an OpenGL texture for the image */
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78 glGenTextures(1, &texture);
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79 glBindTexture(GL_TEXTURE_2D, texture);
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80 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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81 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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82 glTexImage2D(GL_TEXTURE_2D,
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83 0,
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84 GL_RGBA,
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85 w, h,
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86 0,
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87 GL_RGBA,
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88 GL_UNSIGNED_BYTE,
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89 image->pixels);
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90 SDL_FreeSurface(image); /* No longer needed */
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91
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92 return texture;
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93 }
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