glx.pas for JEDI_SDL

[vgo]

I'll turn that into a class some day for easier use, when I get to the GUI part in my engine.

[cairnswm]

Thanks for the Code - I'm going to incorporate it into my libraries.

[grudzio]

Thanks vgo. I think I will convert your code, that it uses SDL_TTF instead of VCL (or LCL).

[vgo]

That would be nice, post the code here if possible.

[savage]

JEDI-SDL does have a SDL_ttf demo that shows how to use it with OpenGL. Look in the SDL_ttf sub-directory.

[grudzio]

All right, here goes the SDL_TTF version of vgo's code. I also used some code from SDL_TTF glfont demo.

[pascal]
unit glFont;

interface

uses
SDL, SDL_TTF, GL;

const
white : TSDL_Color = ( r : $FF; g : $FF; b : $FF; unused : 0 );

type

TFontInfo = record
name : string;
size : integer;
bold,
italic : boolean;
end;

TTextureFont = record
S1, T1, S2, T2: Single;
Width, Height: Integer;
end;

function CreateGLTexture(surface : PSDL_Surface) : gluint;
function CreateFontSurface(info : TFontInfo) : PSDL_Surface;
function BuildFont : gluint;
procedure KillFont(list : gluint);
procedure KillTexture(tex : gluint);

var
TextureFont: array [32 .. 255] of TTextureFont;

implementation

uses
SysUtils;

function CreateFontSurface(info : TFontInfo) : PSDL_Surface;
var
font : PTTF_Font;
surface : PSDL_Surface;
glyphs : array[32..255] of PSDL_Surface;
i,style : integer;
charWidths : array[0..255] of integer;
fontHeight : integer;
textureSize : integer;
x, y, y2 : Integer;
minx,maxx, advance,w : integer;
maxy,miny : integer;
step : single;
r : TSDL_Rect;
begin
//load font
font := TTF_OpenFont(pchar(info.name),info.size);
//set font style
style := TTF_STYLE_NORMAL;
if info.bold then
style := style or TTF_STYLE_BOLD;
if info.italic then
style := style or TTF_STYLE_ITALIC;
TTF_SetFontStyle(font,style);
//set font height and texture size
//TTF_FontHeight returns the maximum height of font
fontHeight := TTF_FontHeight(font);
if fontHeight > 16 then
textureSize := 512
else
textureSize := 256;

writeln(FontHeight);
surface := SDL_CreateRGBSurface(
SDL_SWSURFACE,
textureSize, textureSize,
32,
{$IFDEF IA32} (* OpenGL RGBA masks *)
$000000FF,
$0000FF00,
$00FF0000,
$FF000000
{$ELSE}
$FF000000,
$00FF0000,
$0000FF00,
$000000FF
{$ENDIF}
);

x := 0;
y := textureSize - FontHeight;
y2 := 0;
Step := 1 / textureSize;
//blit char glyphs to the font texture.
for i := 32 to 255 do begin
TTF_GlyphMetrics(font, i,minx, maxx, miny,maxy, advance);
CharWidths[i] := advance;
w := advance;

if (x + w) > textureSize then begin
x := 0;
y := y - FontHeight;
y2 := y2 + FontHeight;
end;

TextureFont[i].S1 := x * Step;
TextureFont[i].T1 := y2 * Step;
TextureFont[i].Width := w;
TextureFont[i].S2 := (x + w) * Step;
TextureFont[i].T2 := (y2 + fontHeight) * Step;
TextureFont[i].Height := FontHeight;
//glyphs[i] := TTF_RenderGlyph_Blended(font,i,white);
glyphs[i] := TTF_RenderGlyph_Solid(font,i,white);
//SDL_SaveBMP(glyphs[i],pchar('glyph'+IntToStr(i)+'.bmp'));
r.x := x;
r.y := y2+(TTF_FontAscent(font)-maxy);
SDL_BlitSurface(glyphs[i],nil,surface,@r);
x := x + w;
end;

SDL_SaveBMP(surface, PChar(info.name+'.bmp'));

for i := 32 to 255 do
SDL_FreeSurface(glyphs[i]);
TTF_CloseFont(font);
Result := surface;
end;

function CreateGLTexture(Surface : PSDL_Surface) : gluint;
var
texture : GLuint;
w, h : integer;
begin
w := surface^.w;
h := surface^.h;
(* Create an OpenGL texture for the image *)
glGenTextures( 1, @texture );
glBindTexture( GL_TEXTURE_2D, texture );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
glTexImage2D( GL_TEXTURE_2D,
0,
GL_RGBA,
w, h,
0,
GL_RGBA,
GL_UNSIGNED_BYTE,
surface^.pixels );
result := texture;
end;
//stores font in OpenGL display list
function BuildFont : gluint;
const
CHAR_SEP = 2;
var
base : gluint;
i : word;
begin
base := glGenLists(255);
for i := 32 to 255 do begin
glNewList(base+i,GL_COMPILE);
glBegin(GL_QUADS);
glTexCoord2f(textureFont[i].s1, textureFont[i].t1);
glVertex2i(0,0);
glTexCoord2f(textureFont[i].s2, textureFont[i].t1);
glVertex2i(textureFont[i].width,0);
glTexCoord2f(textureFont[i].s2, textureFont[i].t2);
glVertex2i(textureFont[i].width,textureFont[i].height);
glTexCoord2f(textureFont[i].s1, textureFont[i].t2);
glVertex2i(0,textureFont[i].height);
glEnd;
glTranslatef(textureFont[i].width+CHAR_SEP,0,0);
glEndList;
end;
Result := base;
end;

procedure KillFont(list : gluint);
begin
glDeleteLists(list,255);
end;

procedure KillTexture(tex : gluint);
begin
glDeleteTextures(1,@tex);
end;

end.

[/pascal]

And here is test app.
[pascal]
program test_font;

uses
SysUtils,
SDL,
SDL_ttf,GL, glfont;

const
SCREEN_WIDTH = 640;
SCREEN_HEIGHT = 480;
SCREEN_BPP = 0;

var
event : TSDL_Event;
done : boolean;
screen, fontSurface : PSDL_Surface;
fontInfo : TFontInfo = (name : 'freesansbold.ttf'; size : 24; bold : false; italic : false);
fontListBase : gluint;
fontTexture : glUint;

procedure printText(x,y : integer; txt : string);
begin
glPushMAtrix;
glTranslatef(x,y,0);
glPushAttrib(GL_LIST_BIT);
glListBase(fontListBase);
glCallLists(Length(txt),GL_UNSIGNED_BYTE,PChar(txt ));
glPopMatrix;
glPopAttrib;
end;

procedure ShutDownApplication( HaltStatus : integer );
begin
TTF_Quit;
SDL_Quit;
Halt( HaltStatus );
end;

begin
{ Initialize SDL }
if ( SDL_Init( SDL_INIT_VIDEO ) < 0 ) then
begin
SDL_Quit;
end;

if ( TTF_Init < 0 ) then
begin
//fprintf(stderr, 'Couldn't initialize TTF: %s',SDL_GetError);
SDL_Quit;
end;

{ Set a 640x480x8 video mode }
screen := SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_OPENGL );
if ( screen = nil ) then
begin
ShutDownApplication( 2 );
end;

// Set the window manager title bar
// SDL_WM_SetCaption( 'JEDI-SDL 3D TTF Demo', 'glfont' );
glViewport( 0, 0, screen_width, screen_height );
glMatrixMode( GL_PROJECTION );
glLoadIdentity;
glOrtho( 0.0, screen_width, screen_height, 0.0, -1.0, 1.0 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity;
glEnable(GL_TEXTURE_2D);


fontSurface := createFontSurface(fontInfo);
fontTexture := CreateGLTexture(fontSurface);
fontListBase := BuildFont;
SDL_FreeSurface(fontSurface);

done := false;
while ( not done ) do
begin
while ( SDL_PollEvent( @event ) <> 0 ) do
begin
case event.type_ of
SDL_KEYDOWN, SDL_QUITEV : done := true;
end;
end;

glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
glLoadIdentity;

glBindTexture(GL_TEXTURE_2D,fontTexture);
printText(0,0, 'The quick brown fox jumps over the lazy dog.');
SDL_GL_SwapBuffers;
end;

KillFont(fontListBase);
KillTexture(fontTexture);
ShutDownApplication( 0 );
end.
[/pascal]

There are problems when font is bold and/or italic. It displays font but aved bmp looks weird. Same problem is when instead of TTF_GlyphRender_solid, TTF_GlyphRender_Blended is used.
Ok. Its time to get some sleep. I am starting to see to many quick brown foxes jumping over lazy dogs...

[begin]

xiexie everybody!

[savage]

Ni hao ma? Ni huay shuo xing wen ma?