1. #include <gl/glut.h>
    2. #include <iostream>
    4. #include <ft2build.h>
    5. #include FT_FREETYPE_H
    7. using namespace std;
    9. #define PIXEL_SIZE 20 //字体的像素大小
    10. wchar_t ch = L'你';
    11. FT_Library ftLibrary;
    12. FT_Face ftFace;
    13. GLuint  texture;
    15. void print(GLubyte *rgba);
    17. void ConvertMONOToRGBA(FT_Bitmap *source, GLubyte *rgba)
    18. {
    19.     GLubyte *s = source->buffer;
    20.     GLubyte *t = rgba;
    22.     for(GLuint y = source->rows; y > 0; y--)
    23.     {
    24.         GLubyte *ss = s;
    25.         GLubyte *tt = t;
    27.         for(GLuint x = source->width >> 3; x > 0; x--)
    28.         {
    29.             GLuint val = *ss;
    31.             for(GLuint i = 8; i > 0; i--)
    32.             {
    33.                 tt[0] = tt[1] = tt[2] = tt[3] = (val & (1 << (i - 1))) ? 0xFF : 0x00;
    34.                 tt += 4;
    35.             }
    37.             ss += 1;
    38.         }
    40.         GLuint rem = source->width & 7;
    42.         if(rem > 0)
    43.         {
    44.             GLuint val = *ss;
    46.             for(GLuint x = rem; x > 0; x--)
    47.             {
    48.                 tt[0] = tt[1] = tt[2] = tt[3] = (val & 0x80) ? 0xFF : 0x00;
    49.                 tt += 4;
    50.                 val <<= 1;
    51.             }
    52.         }
    54.         s += source->pitch;
    55.         t += source->width * 4;    //pitch
    56.     }
    57. }
    59. //FreeType的灰色模式：1个像素用1个字节保存。
    60. void ConvertGRAYToRGBA(FT_Bitmap *source, GLubyte *rgba) //灰度图转RGBA
    61. {
    62.     for(GLuint y = 0; y < source->rows; y++)
    63.     {
    64.         for(GLuint x = 0; x < source->width; x++)
    65.         {
    66.             GLubyte *s = &source->buffer[(y * source->pitch) + x];
    67.             GLubyte *t = &rgba[((y * source->pitch) + x) * 4];
    69.             t[0] = t[1] = t[2] = 0xFF; //RGB为255
    70.             t[3] = *s; //A通道存灰度图
    71.         }
    72.     }
    73. }
    75. GLubyte* get_rgba(FT_Bitmap& bitmap)
    76. {
    77.     int rgbaSize = bitmap.rows * bitmap.rows * 4;
    78.     GLubyte *rgba = new GLubyte[rgbaSize];
    80.     switch(bitmap.pixel_mode)     //像素模式
    81.     {
    82.     case FT_PIXEL_MODE_MONO: //黑白
    83.     {
    84.         // 将黑白转成RGBA
    85.         ConvertMONOToRGBA(&bitmap, rgba);
    86.         break;
    87.     }
    89.     case FT_PIXEL_MODE_GRAY: //灰度
    90.     {
    91.         ConvertGRAYToRGBA(&bitmap, rgba); //灰度转RGBA
    92.         break;
    93.     }
    95.     default:
    96.     {
    97.         memset(rgba, 0xFF, rgbaSize);
    98.         break;
    99.     }
    101.     }
    103.     return rgba;
    104. }
    106. GLubyte* get_rgba_2(FT_Bitmap& bitmap) //自己写的，对位图的理解有不足
    107. {
    108.     int rgbaSize = bitmap.rows * bitmap.rows * 4;
    109.     GLubyte *rgba = new GLubyte[rgbaSize];
    111.     for(GLuint y = 0; y < bitmap.rows; y++)
    112.     {
    113.         for(GLuint x = 0; x < bitmap.width; x++)
    114.         {
    115.             GLubyte *s = &bitmap.buffer[y * bitmap.pitch + x / 8];
    116.             GLubyte *t = &rgba[((y * bitmap.width) + x) * 4];
    118.             if((*s & (0xC0 >> (x % 8))) == 0)  //非字符像素
    119.             {
    120.                 t[0] = t[1] = t[2] = t[3] = 0x00;
    121.             }
    122.             else //字符像素
    123.             {
    124.                 t[0] = t[1] = t[2] = t[3] = 0xff;
    125.             }
    126.         }
    127.     }
    129.     return rgba;
    130. }
    132. void init()
    133. {
    134.     #pragma region FreeType的设置
    135.     // - 初始化FreeType对象
    136.     FT_Init_FreeType(&ftLibrary);
    138.     FT_New_Face(ftLibrary,
    139.                 "C:\\WINDOWS\\Fonts\\simhei.ttf", //黑体中文字库
    140.                 0,
    141.                 &ftFace);
    143.     // - 设置
    144.     FT_Set_Pixel_Sizes(ftFace, PIXEL_SIZE, 0); //像素大小
    146.     // - 得到字符码的字形索引
    147.     FT_UInt uiGlyphIndex = FT_Get_Char_Index(ftFace, ch);
    149.     if(uiGlyphIndex <= 0)
    150.     {
    151.         printf("未找到该字符的索引");
    152.     }
    154.     FT_Load_Glyph(ftFace, uiGlyphIndex, FT_LOAD_DEFAULT);
    155.     #pragma endregion
    158.     #pragma region 生成位图
    160.     // - 生成位图：FreeType所得是8位的灰度图
    161.     if(ftFace->glyph->format != FT_GLYPH_FORMAT_BITMAP)
    162.     {
    163.         FT_Render_Glyph(ftFace->glyph, FT_RENDER_MODE_MONO);
    164.     }
    166.     // - 查看位图信息
    167.     printf("行：%d;列：%d\n", ftFace->glyph->bitmap.rows, ftFace->glyph->bitmap.width);
    168.     printf("\n------ 位图信息 ------\n");
    170.     for(int iRow = 0; iRow < ftFace->glyph->bitmap.rows; iRow++)
    171.     {
    172.         for(int iCol = 0; iCol < ftFace->glyph->bitmap.width; iCol++)
    173.         {
    174.             printf("%d\t", ftFace->glyph->bitmap.buffer[iRow * ftFace->glyph->bitmap.pitch + iCol / 8]);
    175.         }
    177.         printf("\n");
    178.     }
    180.     #pragma endregion
    182.     #pragma region 打印成字体
    183.     printf("\n------ 查看字体信息 ------\n");
    185.     for(int iRow = 0; iRow < ftFace->glyph->bitmap.rows; iRow++)
    186.     {
    187.         for(int iCol = 0; iCol < ftFace->glyph->bitmap.width; iCol++)
    188.         {
    189.             auto index = iRow * ftFace->glyph->bitmap.pitch + iCol / 8;
    190.             auto tmp = 0xC0 >> (iCol % 8);
    191.             auto value = index & tmp;
    193.             if((ftFace->glyph->bitmap.buffer[iRow * ftFace->glyph->bitmap.pitch + iCol / 8] & (0xC0 >> (iCol % 8))) == 0)
    194.             {
    195.                 printf(" ");
    196.             }
    197.             else
    198.             {
    199.                 printf("1");
    200.             }
    201.         }
    203.         printf("\n");
    204.     }
    206.     #pragma endregion
    208.     #pragma region 生成纹理
    209.     // 生成纹理
    210.     glEnable(GL_TEXTURE_2D);
    211.     glGenTextures(1, &texture);
    212.     glBindTexture(GL_TEXTURE_2D, texture);
    214.     GLubyte* rgba = get_rgba(ftFace->glyph->bitmap);
    215.     //GLubyte* rgba = get_rgba_2(ftFace->glyph->bitmap);
    217.     print(rgba);
    218.     glTexImage2D(GL_TEXTURE_2D,
    219.                  0,
    220.                  GL_RGBA,
    221.                  ftFace->glyph->bitmap.width, ftFace->glyph->bitmap.rows,
    222.                  0,
    223.                  GL_RGBA,
    224.                  GL_UNSIGNED_BYTE,
    225.                  rgba);
    226.     delete rgba;
    228.     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    229.     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    231.     glBindTexture(GL_TEXTURE_2D, 0); //解绑
    232.     #pragma endregion
    234.     // 清空资源
    235.     FT_Done_Face(ftFace);
    236.     FT_Done_FreeType(ftLibrary);
    237. }
    239. void myDisplay(void)
    240. {
    241.     glClear(GL_COLOR_BUFFER_BIT);
    242.     glClearColor(0, 0, 0, 0);
    244.     // 画纹理
    245.     glBindTexture(GL_TEXTURE_2D, texture);
    246.     glBegin(GL_QUADS);
    247.     // 要注意字体纹理和OpenGL的绘制关系
    248.     glTexCoord2d(0, 0);         //纹理 左下角
    249.     glVertex2f(-0.8f, 0.8f);    //OpenGL 左上角
    251.     glTexCoord2d(0, 1);         //左上角
    252.     glVertex2f(-0.8f, -0.8f);   //左下角
    254.     glTexCoord2f(1.0f, 1.0f);   //右上角
    255.     glVertex2f(0.8f, -0.8f);    //右下角
    257.     glTexCoord2d(1, 0);         //右下角
    258.     glVertex2f(0.8f, 0.8f);     //右上角
    260.     glEnd();
    261.     glFlush();
    262. }
    264. int main(int argc, char *argv[])
    265. {
    266.     glutInit(&argc, argv);                          //初始化GLUT
    267.     glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);    //初始化显示模式
    268.     glutInitWindowPosition(100, 100);               //窗体位置
    269.     glutInitWindowSize(500, 500);                   //窗体大小
    270.     glutCreateWindow("OpenGL One Char");            //传入窗口名称，并开窗
    272.     init();
    273.     glutDisplayFunc(&myDisplay);                    //绘制的回调函数
    275.     glutMainLoop();                                 //循环绘制
    276.     return 0;
    277. }
    279. void print(GLubyte *rgba) //打印RGBA
    280. {
    281.     printf("\n----- R -----\n");
    283.     for(GLuint y = 0; y < ftFace->glyph->bitmap.rows; y++)
    284.     {
    285.         for(GLuint x = 0; x < ftFace->glyph->bitmap.width; x++)
    286.         {
    287.             GLubyte *s = &ftFace->glyph->bitmap.buffer[(y * ftFace->glyph->bitmap.pitch) + x];
    288.             GLubyte *t = &rgba[((y * ftFace->glyph->bitmap.pitch) + x) * 4];
    290.             printf("%d\t", t[0]);
    291.         }
    293.         printf("\n");
    294.     }
    296.     printf("\n----- G -----\n");
    298.     for(GLuint y = 0; y < ftFace->glyph->bitmap.rows; y++)
    299.     {
    300.         for(GLuint x = 0; x < ftFace->glyph->bitmap.width; x++)
    301.         {
    302.             GLubyte *s = &ftFace->glyph->bitmap.buffer[(y * ftFace->glyph->bitmap.pitch) + x];
    303.             GLubyte *t = &rgba[((y * ftFace->glyph->bitmap.pitch) + x) * 4];
    305.             printf("%d\t", t[1]);
    306.         }
    308.         printf("\n");
    309.     }
    311.     printf("\n----- B -----\n");
    313.     for(GLuint y = 0; y < ftFace->glyph->bitmap.rows; y++)
    314.     {
    315.         for(GLuint x = 0; x < ftFace->glyph->bitmap.width; x++)
    316.         {
    317.             GLubyte *s = &ftFace->glyph->bitmap.buffer[(y * ftFace->glyph->bitmap.pitch) + x];
    318.             GLubyte *t = &rgba[((y * ftFace->glyph->bitmap.pitch) + x) * 4];
    320.             printf("%d\t", t[2]);
    321.         }
    323.         printf("\n");
    324.     }
    326.     printf("\n----- A -----\n");
    328.     for(GLuint y = 0; y < ftFace->glyph->bitmap.rows; y++)
    329.     {
    330.         for(GLuint x = 0; x < ftFace->glyph->bitmap.width; x++)
    331.         {
    332.             GLubyte *s = &ftFace->glyph->bitmap.buffer[(y * ftFace->glyph->bitmap.pitch) + x];
    333.             GLubyte *t = &rgba[((y * ftFace->glyph->bitmap.pitch) + x) * 4];
    335.             printf("%d\t", t[3]);
    336.         }
    338.         printf("\n");
    339.     }
    340. }