[gameprogrammer] Re: SDL_ttf and OpenGL

On Fri, 2004-04-30 at 09:25, Kevin Fields wrote:
> I would never have thought of doing that.

Doing what? 

> My knowledge of both SDL and OpenGL are still rather limited.

Don't worry about it. You'll get there. 

                Bob Pendleton

> 
> 
> From: Bob Pendleton <bob@xxxxxxxxxxxxx>
> Reply-To: gameprogrammer@xxxxxxxxxxxxx
> To: Gameprogrammer Mailing List <gameprogrammer@xxxxxxxxxxxxx>
> Subject: [gameprogrammer] Re: SDL_ttf and OpenGL
> Date: Thu, 29 Apr 2004 09:48:39 -0500
> 
> On Thu, 2004-04-29 at 07:22, Kevin Fields wrote:
>  > Hey people,
>  >
>  > I'm having an issue with trying to get SDL_ttf to work with OpenGL.
>  > I've posted on the SDL mailing list, but I'm still not sure how I can go
>  > about getting SDL_ttf to render to the screen.
>  >
>  > One method I was told to use was to take the surface generated by
>  > TTF_RenderText_*() and make a texture out of it, then applying that 
> texture
>  > to a quad (or triangle strip) and rendering to the screen. When I tried
>  > that, nothing appeared.
>  >
>  > Has anyone been able to get fonts working with SDL and OpenGL?
> 
> I've been so involved in this list (my list) for the last few days that
> I have not been looking at the SDL list and missed you question. I have
> indeed gotten SDL_ttf to work with OpenGL. It isn't difficult. Here is
> some code that I use for the job:
> 
> //-------------------------------------------------
> 
> class Font
> {
> private:
>    static const int minGlyph = ' ';
>    static const int maxGlyph = 126;
> 
>    static int initCounter;
> 
>    typedef struct
>    {
>      int minx, maxx;
>      int miny, maxy;
>      int advance;
>      SDL_Surface *pic;
>      GLuint tex;
>      GLfloat texMinX, texMinY;
>      GLfloat texMaxX, texMaxY;
>    } glyph;
> 
>    int height;
>    int ascent;
>    int descent;
>    int lineSkip;
>    glyph glyphs[maxGlyph + 1];
> 
>    unsigned char *address;
>    int length;
>    int pointSize;
>    int style;
>    float fgRed, fgGreen, fgBlue;
>    float bgRed, bgGreen, bgBlue;
> 
>    TTF_Font *ttfFont;
> 
>    SDL_Color foreground;
>    SDL_Color background;
> 
>    void loadChar(char c)
>    {
>      GLfloat texcoord[4];
>      char letter[2] = {0, 0};
> 
>      if ((minGlyph <= c) &&
>          (c <= maxGlyph) &&
>          (NULL == glyphs[c].pic))
>      {
>        SDL_Surface *g0 = NULL;
>        SDL_Surface *g1 = NULL;
> 
>        letter[0] = c;
> 
>        TTF_GlyphMetrics(ttfFont,
>                         (Uint16)c,
>                         &glyphs[c].minx,
>                         &glyphs[c].maxx,
>                         &glyphs[c].miny,
>                         &glyphs[c].maxy,
>                         &glyphs[c].advance);
> 
>        g0 = TTF_RenderText_Shaded(ttfFont,
>                                   letter,
>                                   foreground,
>                                   background);
> 
>        if (NULL != g0)
>        {
>          g1 = SDL_DisplayFormat(g0);
>          SDL_FreeSurface(g0);
>        }
> 
>        if (NULL != g1)
>        {
>          glyphs[c].pic = g1;
>          glyphs[c].tex = loadTextureColorKey(g1, texcoord, 0, 0, 0);
>          glyphs[c].texMinX = texcoord[0];
>          glyphs[c].texMinY = texcoord[1];
>          glyphs[c].texMaxX = texcoord[2];
>          glyphs[c].texMaxY = texcoord[3];
>        }
>      }
>    }
> 
> public:
> 
>    Font(unsigned char *address,
>         int length,
>         int pointSize,
>         int style,
>         float fgRed, float fgGreen, float fgBlue,
>         float bgRed, float bgGreen, float bgBlue):
>      address(address), length(length),
>      pointSize(pointSize),
>      style(style),
>      fgRed(fgRed), fgGreen(fgGreen), fgBlue(fgBlue),
>      bgRed(bgRed), bgGreen(bgGreen), bgBlue(bgBlue),
>      ttfFont(NULL)
>    {
>      if (0 == initCounter)
>      {
>        if (TTF_Init() < 0)
>        {
>          errorExit("Can't init SDL_ttf");
>        }
>      }
>      initCounter++;
>      initFont();
>    }
> 
>    ~Font()
>    {
>      initCounter--;
>      if (0 == initCounter)
>      {
>        TTF_Quit();
>      }
>    }
> 
>    void initFont()
>    {
>      SDL_RWops *src = NULL;
>      int i;
> 
>      src = SDL_RWFromMem(address, length);
> 
>      ttfFont = TTF_OpenFontRW(src, 1, pointSize);
>      if (NULL == ttfFont)
>      {
>        errorExit("Can't open font file");
>      }
> 
>      TTF_SetFontStyle(ttfFont, style);
> 
>      foreground.r = (Uint8)(255 * fgRed);
>      foreground.g  = (Uint8)(255 * fgGreen);
>      foreground.b = (Uint8)(255 * fgBlue);
> 
>      background.r = (Uint8)(255 * bgRed);
>      background.g = (Uint8)(255 * bgGreen);
>      background.b = (Uint8)(255 * bgBlue);
> 
>      height = TTF_FontHeight(ttfFont);
>      ascent = TTF_FontAscent(ttfFont);
>      descent = TTF_FontDescent(ttfFont);
>      lineSkip = TTF_FontLineSkip(ttfFont);
> 
>      for (i = minGlyph; i <= maxGlyph; i++)
>      {
>        glyphs[i].pic = NULL;
>        glyphs[i].tex = 0;
>      }
>    }
> 
>    int getLineSkip()
>    {
>      return lineSkip;
>    }
> 
>    int getHeight()
>    {
>      return height;
>    }
> 
>    void textSize(char *text,
>                  SDL_Rect *r)
>    {
>      int maxx = 0;
>      int advance = 0;
> 
>      r->x = 0;
>      r->y = 0;
>      r->w = 0;
>      r->h = height;
> 
>      while (0 != *text)
>      {
>        if ((minGlyph <= *text) && (*text <= maxGlyph))
>        {
>          loadChar(*text);
> 
>          maxx = glyphs[*text].maxx;
>          advance = glyphs[*text].advance;
>          r->w += advance;
>        }
> 
>        text++;
>      }
> 
>      r->w = r->w - advance + maxx;
>    }
> 
>    void drawText(char *text, int x, int y)
>    {
>      GLfloat left, right;
>      GLfloat top, bottom;
>      GLfloat texMinX, texMinY;
>      GLfloat texMaxX, texMaxY;
> 
>      glPushAttrib(GL_ALL_ATTRIB_BITS);
> 
>      glEnable(GL_BLEND);
>      glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
> 
>      glEnable(GL_TEXTURE_2D);
>      glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
> 
>      while (0 != *text)
>      {
>        if ((minGlyph <= *text) && (*text <= maxGlyph))
>        {
>          loadChar(*text);
> 
>          texMinX = glyphs[*text].texMinX;
>          texMinY = glyphs[*text].texMinY;
>          texMaxX = glyphs[*text].texMaxX;
>          texMaxY = glyphs[*text].texMaxY;
> 
>          left   = x;
>          right  = x + glyphs[*text].pic->w;
>          top    = y;
>          bottom = y + glyphs[*text].pic->h;
> 
>          glBindTexture(GL_TEXTURE_2D, glyphs[*text].tex);
> 
>          glBegin(GL_TRIANGLE_STRIP);
> 
>          glTexCoord2f(texMinX, texMinY); glVertex2f( left,    top);
>          glTexCoord2f(texMaxX, texMinY); glVertex2f(right,    top);
>          glTexCoord2f(texMinX, texMaxY); glVertex2f( left, bottom);
>          glTexCoord2f(texMaxX, texMaxY); glVertex2f(right, bottom);
> 
>          glEnd();
> 
>          x += glyphs[*text].advance;
>        }
> 
>        text++;
>      }
> 
>      glPopAttrib();
>    }
> };
> 
> //-------------------------------------------------
> 
> int Font::initCounter = 0;
> 
>               Bob Pendleton
> 
>  >
>  > _________________________________________________________________
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>  >
> --
> +--------------------------------------+
> + Bob Pendleton: writer and programmer +
> + email: Bob@xxxxxxxxxxxxx             +
> + blog:  www.Stonewolf.net             +
> + web:   www.GameProgrammer.com        +
> +--------------------------------------+
> 
> _________________________________________________________________
> http://join.msn.com/?pgmarket=en-ca&page=byoa/prem&xAPID=1994&DI=1034&SU=http://hotmail.com/enca&HL=Market_MSNIS_Taglines
> 
-- 
+--------------------------------------+
+ Bob Pendleton: writer and programmer +
+ email: Bob@xxxxxxxxxxxxx             +
+ blog:  www.Stonewolf.net             +
+ web:   www.GameProgrammer.com        +
+--------------------------------------+

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