FTGL 1.0b3
August 8 2001
DESCRIPTION:
FTGL is a library a tool to allow OpenGL (www.opengl.org) to render
characters from arbitrary fonts.
Unlike other OpenGL font libraries FTGL uses standard font file formats
so doesn't need a preprocessing step to convert the high quality font data
into a lesser quality, proprietary format.
FTGL uses the Freetype (www.freetype.org) font library to open and 'decode'
the fonts. It then takes that output and stores it in a format most efficient
for OpenGL rendering.
Rendering modes supported are
- Bit maps
- Pix maps
- Texture maps
- Outlines
- Polygon meshes
USAGE:
FTGLPixmapFont font;
font.Open( "Fonts:Arial");
font.FaceSize( 72);
font.render( "Hello World!");
This library was inspired by gltt, Copyright (C) 1998-1999 Stephane Rehel
( gltt.sourceforge.net)
Things to think about...
The whole char size thing is major headache.
At the moment if you call font.CharSize( x) the glyph list is destroyed and
rebuilt, which will be really, really, really inefficient if you change sizes
often. Will the freetype cache stuff help here or should we cache internally?
Multiple glyphlists. glyphlist manager. Multiple glyphLists will chew up
memory. Maybe a <map> will help here, maybe a map will let us cache glyphs
as required rather than all at startup? This wont help texture glyphs.
If a font is defined uniquely by it's face and size ie
font.Open("Fonts:Arial", 72);
Then we don't need FTFace and FTSize, their functionality could be internal
to FTFont. Alternatively if we allow multiple faces and sizes how should
they be handled. The FTSize seems redundant (depends on the out come of the
above). For the time being I'm treating this as a feature!
When is the best time to construct the glyphList? After the call to Size(x)
is the earliest but what happens if the client doesn't set the char size?
Need a way to restrict the glyphs to a custom set. eg an app only needs
numbers so we should only create a glyphList of the number characters.
This will enable us to have a restricted set of HIGH quality glyphs.
Might have to move the init code out of the constructors into an init
function so that they can return errors.
Currently the glyphList is isn't indexed, it's just a vector of glyphs in
glyphIndex order. I'm using the freetype function FT_Get_Char_Index() to
convert char codes to glyphIndices. If this proves to be too slow I will
implement a charmap class that will hold the indices.
good site...http://cgm.cs.mcgill.ca/~luc/
PROFILING
test 1
100,000 frames. Outline Font, No openGL context.
The results of the first profile are in and as expected using freetype to
return the char index for a glyph is costing us. A staggering 10% of the
rendering time in fact!!!
TODO:
- Tidy code, fix compiler warnings, comments.
- Memory Leak in PolyGlyph (glCombine)
- The position stuff is broken again. Check the pen stuff. Plus lower
case 'y's seem to be 1 pixel too low?
- check and confirm the glPixelStore stuff. Data Alignment. Tightly
packed at the moment.
- namespace
- gl/glu errors
- tessellation winding rules
- Distributions MACOS 9/X, IRIX, Linux, Windows
- Test with non English(?) fonts
FUTURE:
- select face ie italic, bold etc
- Multiple sizes
- Optimise performance!! and mem usage.
- don't process chars that map to glyph 0
- Make our own char map processing class
- Use the Freetype Cache mechanism. See above. FTC_xxx
- Alignment. left right, centre.
- Bounding box, char and string.
- Vertical formats
- For platforms that have antialiased lines but not polys we could
outline the polyfonts with lines to get better looking glyphs.
- Provide an interface to access the point data for outlines and polygon
meshes.
- Unicode w_char. May have to use std::wstring and or std::wchar_t.
- Improve the grid fitting scheme in texture fonts.
BUGS:
- Memory corruption in FTTextureFont
- Kerning is screwed up for really small point sizes eg 2 point.
Freetype bug?
- The texture co-ords in the Texture Font made be wrong for none
scalable fonts.
MAC OS:
- Exits with some fonts at large sizes. GLUT Memory Bug?
also with large numbers of glyphs at any size eg helvetica. This
is becoming REALLY annoying!!!
August 21 2001
1.0b4
- Changed the mode for FT_Load_Glyph to FT_LOAD_NO_HINTING | FT_LOAD_NO_BITMAP
for outline and polygon fonts & FT_LOAD_NO_HINTING for texture fonts.
Seems to produce better looking glyphs.
- FTGLTextureFont can now use multiple textures to render glyphs if
they don't fit within a GL_MAX_TEXTURE_SIZE texture.
- Changed FTSize to use bbox for global width and height. Needs more
work (eg float or int?) and need to check inconsistancies in freetype.
- Being more strict with types eg integer indices and sizes are now unsigned.
August 8 2001
1.0b3
- I've made fundamental change to the way the glyphlist is built. This
is to get round the problems I was having with charmaps. At this stage
it is a temporary solution. Previously the glyphList was indexed by
char code. Now it's indexed by glyph index and the conversion is done
by the freetype function FT_Get_Char_Index(). If this proves to be too
slow I'll make my own charmap and use it to index into the glyphlist.
This has fixed all the charmap related problems/bugs.
- Enabled alpha blend in Pixmap font.
- Enabled LINE_SMOOTH in Outline font
- Fixed bug that prevented the display of chars >127
- Moved pixel store stuff out of BitmapGlyph into BitmapFont.
- Minor changes for IRIX (compiles but isn't tested)
- Pixmap fonts can now be in colour. It uses the current colour when the
font is CREATED. This isn't ideal but is better then the alternatives.
- Tidied up the error handling.
- Minor code clean ups.
August 6 2001
BETA release 1.0b2
- Minor tidy ups for first public release.
August 3 2001
First BETA release 1.0b1
- All font types are now working, Bitmaps, Pixmaps, Texture, Outline
and Polygons. Quality of output and performance varies wildly:)
July 22 2001
First ALPHA Release 1.0a1
