OpenTK使用 FreeType2渲染字母范例

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OpenTK库的.Net Wrapping见http://www.codeproject.com/Articles/13296/Rendering-FreeType-2-with-OpenGL
    public class FTText    {        //public static extern int FT_Init_FreeType(out System.IntPtr lib);        //public Bitmap bitmap;        public byte[] expanded;        public int width;        public int height;        public FTText()        {            //初始化库            IntPtr libptr;            if (Library.FT_Init_FreeType(out libptr)!=0)    return;            int size = 50;            IntPtr faceptr;            if (Face.FT_New_Face(libptr, "J:\\GameProject\\GameProject\\Fonts\\Anonymous.ttf", 0, out faceptr)!=0)  return;            Face face = (Face)Marshal.PtrToStructure(faceptr, typeof(Face));            Face.FT_Set_Char_Size(faceptr, size << 6, size << 6, 96, 96);            Face.FT_Set_Pixel_Sizes(faceptr, size, size);            int index = Face.FT_Get_Char_Index(faceptr, ' ');            if (Face.FT_Load_Glyph(faceptr, index, FT_LOAD_TYPES.FT_LOAD_DEFAULT)!=0)   return;            //Convert the glyph to a bitmap            System.IntPtr glyph;            if (Glyph.FT_Get_Glyph(face.glyphrec, out glyph)!=0)    return;            Glyph.FT_Glyph_To_Bitmap(out glyph, FT_RENDER_MODES.FT_RENDER_MODE_NORMAL, 0, 1);            BitmapGlyph glyph_bmp = (BitmapGlyph)Marshal.PtrToStructure(glyph, typeof(BitmapGlyph));            byte[] bmp = new byte[glyph_bmp.bitmap.width * glyph_bmp.bitmap.rows];            Marshal.Copy(glyph_bmp.bitmap.buffer, bmp, 0, bmp.Length);            //Next we expand the bitmap into an opengl texture                 width = next_po2(glyph_bmp.bitmap.width);            height = next_po2(glyph_bmp.bitmap.rows);            //expanded = bmp;            expanded = new byte[2 * width * height];            for (int j = 0; j < height; j++)            {                for (int i = 0; i < width; i++)                {                    expanded[2 * (i + j * width)] = expanded[2 * (i + j * width) + 1] =                        (i >= glyph_bmp.bitmap.width || j >= glyph_bmp.bitmap.rows) ?                        (byte)0 : bmp[i + glyph_bmp.bitmap.width * j];                }            }                        //expanded = null;            bmp = null;            //// Dispose of these as we don't need            Face.FT_Done_Face(faceptr);            Library.FT_Done_FreeType(libptr);        }        internal int next_po2(int a)        {            int rval = 1;            while (rval < a) rval <<= 1;            return rval;        }    }
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