glx.pas for JEDI_SDL

[grudzio]

There is an error in function InitGLXFromLibrary. The if statement should be

if not LoadModule( libGLX, dll ) then exit;

not

 if LoadModule( libGLX, dll ) then exit;

In present form it loads library and exits witout initialising glx functions.

[savage]

Thanks for pointing it out. I'll try and commit the change to CVS this evening.

[cragwolf]

I've never used glx; the X-Windows library gives me the shakes. I've had a go at gtkglext, though. Looks pretty cool, but I think I'll stick with JEDI-SDL while it's still cooking.

[savage]

The fix is now part of CVS. Thanks again.

[grudzio]

I've never used glx; the X-Windows library gives me the shakes. I've had a go at gtkglext, though. Looks pretty cool, but I think I'll stick with JEDI-SDL while it's still cooking.

I only need glxUseXFont to create fonts in my app. And yes, xlib programing
is even more dificult than Win API

[cragwolf]

I only need glxUseXFont to create fonts in my app.

Have you tried sdl_ttf? I suppose that's another possibility. I just use premade font textures; it's simple but not as flexible.

And yes, xlib programing is even more dificult than Win API

Heheh, WinAPI is a distant memory for me having used Linux for the past few years.

[grudzio]

The problem with textured font is that you need a texture . I could not find any font generating utility for linux and was too lazy to make my own.
As for SDL_TTF, I dont like the idea of generating new openGL texture each time I want to print something an the screen. So I am stuck with glxUseFont.

[cragwolf]

The problem with textured font is that you need a texture . I could not find any font generating utility for linux and was too lazy to make my own.

Yes, I created my fonts in the GIMP, and used a monospace font to be sure of the spacing. It was very tedious.

[vgo]

Creating the font texture on-the-fly is easy if you have some kind of surface to draw the fonts in the system to, like TBitMap.

Here's some old code of mine, should be easy to port to Lazarus:

[pascal]
{$R-}
unit J3D_Text;

interface

uses Windows, OpenGL, Graphics;

type
ThTexture = array [0..0] of Byte;
TTexture = ^ThTexture;

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

var
TextureFont: array [' ' .. '~'] of TTextureFont;
TextureID: Longword;
TextureSize: Longword;
FontTexture: TTexture; // Texture


procedure Text_LoadFont(Fontname: String; Size: Integer; Color: TColor);

implementation

procedure Text_LoadFont(Fontname: String; Size: Integer; Color: TColor);

const
z: Integer = 0;
var
BitMap: TBitMap;
x: Integer;
y: Integer;
y2: Integer;
z2: Integer;
Delphi_Color: TColor;
Font: TFont;

FontHeight: Integer;
r: TRect;
CharWidths: array [0..255] of Integer;
CharHeights: array [0..255] of Integer;
FontWidth: Integer;
Step: Single;
Chr: Char;
begin
// Create and load bitmap
BitMap := TBitMap.Create;
//BitMap.LoadFromFile(FileName);
BitMap.PixelFormat := pf24bit;

BitMap.Width := 256;
BitMap.Height := 256;

r.Left := 0;
r.Right := 256;
r.Top := 0;
r.Bottom := 256;

BitMap.Canvas.Brush.Color := clBlack;
BitMap.Canvas.Brush.Style := bsSolid;
BitMap.Canvas.Pen.Color := clBlack;
BitMap.Canvas.FillRect(r);
BitMap.Canvas.Font.Name := Fontname; // Arial
BitMap.Canvas.Font.Size := Size; // 18
BitMap.Canvas.Font.Color := Color; //clWhite
BitMap.Canvas.Font.Style := [];
FontWidth := BitMap.Canvas.Font.Size - 4;
FontHeight := Round(BitMap.Canvas.Font.Size * BitMap.Canvas.Font.PixelsPerInch / 72);

for x := 0 to 255 do
CharWidths[x] := BitMap.Canvas.TextWidth(Char(x));

FontHeight := 0;
for x := 0 to 255 do
begin
CharHeights[x] := BitMap.Canvas.TextHeight(Char(x));
if BitMap.Canvas.TextHeight(Char(x)) > FontHeight then
FontHeight := BitMap.Canvas.TextHeight(Char(x));
end;

Step := 1 / 256;

x := 0;
y := 255 - FontHeight;
y2 := 0;
for z2 := 32 to 126 do
begin
Chr := Char(z);
FontWidth := CharWidths[z2];
//FontHeight := CharHeights[z];
if (x + FontWidth) > 255 then
begin
x := 0;
y := y - FontHeight;
//y := y + FontHeight;
y2 := y2 + FontHeight;
end;

TextureFont[Char(z2)].S1 := x * Step;
TextureFont[Char(z2)].T1 := y2 * Step;
TextureFont[Char(z2)].Width := FontWidth-1;
TextureFont[Char(z2)].S2 := (x + FontWidth-1) * Step;
TextureFont[Char(z2)].T2 := (y2 + CharHeights[z2]) * Step;
TextureFont[Char(z2)].Height := CharHeights[z2];
BitMap.Canvas.TextOut(x, y, Char(z2));
x := x + FontWidth;
end;

// Create and set size of texture
TextureSize := BitMap.Width * BitMap.Height;

GetMem(FontTexture, TextureSize * 3);

//BitMap.SaveToFile('c:\temp\font.bmp');

// Position in texture
z := 0;
for y := BitMap.Height - 1 downto 0 do
begin
for x := 0 to BitMap.Width - 1 do
begin
// Converts Delphi Color value to RGB values, no Alpha
Delphi_Color := BitMap.Canvas.Pixels[x, y];
FontTexture[z] := Lo(LoWord(Delphi_Color));
Inc(z);
FontTexture[z] := Hi(LoWord(Delphi_Color));
Inc(z);
FontTexture[z] := Lo(HiWord(Delphi_Color));
Inc(z);
end;
end;
// glGenTextures(1, TextureID);
TextureID := 100;
glBindTexture(GL_TEXTURE_2D, TextureID);

// Used texture format is size = 256x256, format = 3 (RGB) and type unsigned byte
glTexImage2D(GL_TEXTURE_2D, 0, 3, 256, 256, 0, GL_RGB, GL_UNSIGNED_BYTE, FontTexture);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

BitMap.Free;
end;

initialization

finalization
if FontTexture <> NIL then
FreeMem(FontTexture, TextureSize * 3);

end.
[/pascal]

[cragwolf]

Thanks for the code. That's a nice solution for users of the Delphi VCL or the Lazarus LCL.