OpenGL_ES加载TGA/BMP纹理

清疚 2022-08-05 02:13 350阅读 0赞 
  1. typedef struct TGAImage                                            {
  2.     GLubyte    *imageData;                                            //     图像数据
  3.     GLuint    bpp;                                                //     像素颜色深度
  4.     GLuint    width;                                                //      图像宽度
  5.     GLuint    height;                                                //     图像高度
  6.     GLuint    texID;                                                                    //    纹理ID
  7. } TGAImage;    
  8. bool LoadTGA(TGAImage *texture, char *filename)
  9. {
  10.     GLubyte        TGAheader[12]={0,0,2,0,0,0,0,0,0,0,0,0};        // Uncompressed TGA Header            不压缩的TGA头
  11.     GLubyte        TGAcompare[12];                                    // Used To Compare TGA Header        压缩的
  12.     GLubyte        header[6];                                        // First 6 Useful Bytes From The Header        TGA头的前6个有用的字节
  13.     GLuint        bytesPerPixel;                                    // Holds Number Of Bytes Per Pixel Used In The TGA File        TGA文件每个像素使用的字节
  14.     GLuint        imageSize;                                        // Used To Store The Image Size When Setting Aside Ram
  15.     GLuint        temp;                                            // Temporary Variable        临时变量
  16.     GLuint        type=GL_RGBA;                                    // Set The Default GL Mode To RBGA (32 BPP)    默认的GL模式
  17.     FILE *file = fopen(filename, "rb");                            // Open The TGA File
  18.     printf("TGA_file=%d/n",file);
  19.     if(    file==NULL ||                                            // Does File Even Exist?
  20.         fread(TGAcompare,1,sizeof(TGAcompare),file)!=sizeof(TGAcompare) ||    // Are There 12 Bytes To Read?        是否读到12字节数据
  21.         memcmp(TGAheader,TGAcompare,sizeof(TGAheader))!=0                ||    // Does The Header Match What We Want?    是否是压缩的，压缩的就读取失败，关闭file
  22.         fread(header,1,sizeof(header),file)!=sizeof(header))                // If So Read Next 6 Header Bytes        再读6个字节
  23.     {
  24.         if (file == NULL)                                        // Did The File Even Exist? *Added Jim Strong*
  25.             return false;                                        // Return False
  26.         else                                                    // Otherwise
  27.         {
  28.             fclose(file);                                        // If Anything Failed, Close The File
  29.             return false;                                        // Return False
  30.         }
  31.     }
  33.     //12到17字节前四字节是图像宽高，第五字节是图像位深度
  34.     texture->width  = header[1] * 256 + header[0];                // Determine The TGA Width    (highbyte*256+lowbyte)//低字节，高字节
  35.     texture->height = header[3] * 256 + header[2];                // Determine The TGA Height    (highbyte*256+lowbyte)
  36.     if(    texture->width    <=0    ||                                    // Is The Width Less Than Or Equal To Zero
  37.         texture->height    <=0    ||                                    // Is The Height Less Than Or Equal To Zero
  38.         (header[4]!=24 && header[4]!=32))                        // Is The TGA 24 or 32 Bit?        
  39.     {
  40.         fclose(file);                                            // If Anything Failed, Close The File
  41.         return false;                                            // Return False
  42.     }
  43.     texture->bpp    = header[4];                                // Grab The TGA's Bits Per Pixel (24 or 32)
  44.     bytesPerPixel    = texture->bpp/8;                            // Divide By 8 To Get The Bytes Per Pixel    每个像素使用的字节数
  45.     imageSize        = texture->width*texture->height*bytesPerPixel;    // Calculate The Memory Required For The TGA Data
  46.     texture->imageData=(GLubyte *)malloc(imageSize);            // Reserve Memory To Hold The TGA Data    申请内存
  47.     if(    texture->imageData==NULL ||                                // Does The Storage Memory Exist?
  48.         fread(texture->imageData, 1, imageSize, file)!=imageSize)    // Does The Image Size Match The Memory Reserved?    图像数据保存到纹理结构数据缓存imageData中
  49.     {//失败情况下释放资源
  50.         if(texture->imageData!=NULL)                            // Was Image Data Loaded
  51.             free(texture->imageData);                            // If So, Release The Image Data
  52.         fclose(file);                                            // Close The File
  53.         return false;                                            // Return False
  54.     }
  55.     for(GLuint i=0; i<int(imageSize); i+=bytesPerPixel)            // Loop Through The Image Data
  56.     {                                                            // Swaps The 1st And 3rd Bytes ('R'ed and 'B'lue)
  57.         temp=texture->imageData[i];                                // Temporarily Store The Value At Image Data 'i'
  58.         texture->imageData[i] = texture->imageData[i + 2];        // Set The 1st Byte To The Value Of The 3rd Byte
  59.         texture->imageData[i + 2] = temp;                        // Set The 3rd Byte To The Value In 'temp' (1st Byte Value)
  60.     }
  61.     fclose (file);                                                // Close The File
  62.     glGenTextures(1, &texture->texID);                            // Generate生产，产生 OpenGL texture IDs
  63.     printf("纹理ID=%d/n",texture->texID );
  64.     glBindTexture(GL_TEXTURE_2D, texture->texID);                        // Bind 绑定Our Texture
  65.     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);    // Linear Filtered
  66.     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);    // Linear Filtered
  67.     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  68.     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  69.     if (texture[0].bpp==24)                                        // Was The TGA 24 Bits
  70.     {
  71.         type=GL_RGB;                                            // If So Set The 'type' To GL_RGB
  72.     }
  73.     //创建纹理
  74.     glTexImage2D(GL_TEXTURE_2D, 0, type, texture->width, texture->height, 0, type, GL_UNSIGNED_BYTE, texture->imageData);
  75.     return true;
  76. }
  77. bool LoadBMP(TGAImage *texture, char *filename)
  78. {
  80.     BITMAPFILEHEADER    bmpFileHeader;        //bmp文件头 
  81.     BITMAPINFOHEADER    bmpInfoHeader;             //bmp格式头   
  82.     GLuint        imageSize;                                        //纹理数据大小
  83.     GLuint        temp;                                            //         临时变量
  84.     GLuint        type=GL_RGB;                                    
  85.     FILE *file = fopen(filename, "rb");                        
  86.     printf("BMP_file=%d/n",file);    
  87.     if(    file==NULL)                                            // Does File Even Exist?
  88.         return    false;
  89.     fread(&bmpFileHeader,1,sizeof(BITMAPFILEHEADER),file);    //读取文件头 
  90.     if(bmpFileHeader.bfType!=0x4d42)                        //判断是否是BM 
  91.         return    false;
  92.     else
  93.         printf("是bmp图像/n");
  95.     fread(&bmpInfoHeader,1,sizeof(BITMAPINFOHEADER),file);        //    读取信息头
  96.     texture->width    =    bmpInfoHeader.biWidth;                //图片宽度
  97.     texture->height    =    bmpInfoHeader.biHeight;                //图片高度
  98.     texture->bpp    =    bmpInfoHeader.biBitCount;            //位深度
  99.     imageSize        =    bmpInfoHeader.biSizeImage ;            //图像数据的大小，用作申请纹理缓存
  100.     if(    texture->width    <=0    ||                                    
  101.         texture->height    <=0    ||                                    
  102.         texture->bpp!=24)                                    // bmp不是24位图    
  103.     {
  104.         fclose(file);                                        
  105.         return false;                                        
  106.     }
  107.     //BITMAPFILEHEADER.bfOffBits从文件头开始到颜色数据的偏移量
  108.     fseek(file,bmpFileHeader.bfOffBits,SEEK_SET);    //移动指针到图像数据
  109.     texture->imageData=(GLubyte *)malloc(imageSize);
  110.     if(    texture->imageData==NULL ||                                // Does The Storage Memory Exist?
  111.         fread(texture->imageData, 1, imageSize, file)!=imageSize)    // Does The Image Size Match The Memory Reserved?    图像数据保存到纹理结构数据缓存imageData中
  112.     {
  113.         //失败情况下释放资源
  114.         if(texture->imageData!=NULL)                            // Was Image Data Loaded
  115.             free(texture->imageData);                            // If So, Release The Image Data
  116.         fclose(file);                                            // Close The File
  117.         return false;                                            // Return False
  118.     }
  119.     for(GLuint i=0; i<int(imageSize); i+=texture->bpp/8)        // Loop Through The Image Data
  120.     {                                                            // Swaps The 1st And 3rd Bytes ('R'ed and 'B'lue)
  121.         temp=texture->imageData[i];                                // Temporarily Store The Value At Image Data 'i'
  122.         texture->imageData[i] = texture->imageData[i + 2];        // Set The 1st Byte To The Value Of The 3rd Byte
  123.         texture->imageData[i + 2] = temp;                        // Set The 3rd Byte To The Value In 'temp' (1st Byte Value)
  124.     }
  125.     fclose (file);                                                // Close The File
  126.     glGenTextures(1, &texture->texID);                            // Generate生产，产生 OpenGL texture IDs
  127.     printf("纹理ID=%d/n",texture->texID );
  128.     glBindTexture(GL_TEXTURE_2D, texture->texID);                        // Bind 绑定Our Texture
  129.     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);    // Linear Filtered
  130.     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);    // Linear Filtered
  131.     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  132.     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  133.     //创建纹理
  134.     glTexImage2D(GL_TEXTURE_2D, 0, type, texture->width, texture->height, 0, type, GL_UNSIGNED_BYTE, texture->imageData);
  135.     return true;
  136. }
  137. 使用：
  138.     /*LoadTGA(&MainImage,"//NAND//skyworth//tga//main.tga/0");
  139.     LoadTGA(&MovieImage,"//NAND//skyworth//tga//movie.tga");*/
  140.     LoadBMP(&MainImage,"//USER//tv.bmp/0");
  141.     LoadBMP(&MovieImage,"//USER//music.bmp/0");

本文转自：http://blog.csdn.net/ezhong0812/article/details/6401723

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