Is there a decent OpenGL text drawing library for the iPhone SDK?

Question

I\'m trying to figure out a simple to draw some text in OpenGL. My research has shown its a fairly complex task. It involves creating (or generating at runtime) a font atl

Answer 1

Yes, there are 2 that I know of. The trick is, you have to render to texture using Quartz (CGContext* functions), then render that texture for the user to see.

If you're concerned about performance, you can also use Quartz to generate your texture atlas.

It's fairly easy to whip up a texture generation tool (in xCode) once you know the basics of rendering a font.

All you have to do is have a valid CGContext. You can find some really great sample code in this texture loader.

Basically the code goes:

// Create the cgcontext as shown by links above

// Now to render text into the cg context,
// the drop the raw data behind the cgcontext
// to opengl.  2 ways to do this:
// 1)  CG* way: (advantage: easy to use color)
CGContextSelectFont(cgContext, "Arial", 24, kCGEncodingMacRoman);

// set color to yellow text
CGContextSetRGBFillColor(cgContext, 1, 1, 0, 1) ; // Be sure to use FILL not stroke!

// draw it in there
CGContextShowTextAtPoint(cgContext, 20, 20, "HI THERE", strlen("HI THERE") ) ;

/*
// WAY #2:  this way it's always black and white
// DRAW SOME TEXT IN IT
// that works ok but let's try cg to control color
UIGraphicsPushContext(cgContext);
UIFont *helv = [UIFont fontWithName:@"Helvetica" size:[UIFont systemFontSize]];
NSString* msg = @"Hi hello" ;  
[msg drawInRect:CGRectMake(0,0,pow2Width,pow2Height) withFont:helv] ;
    UIGraphicsPopContext();
*/

// put imData into OpenGL's memory
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, pow2Width, pow2Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imData);
CHECK_GL ;

It comes out looking pretty good and antialiased,

A list of ios fonts is available here, and with prerenders here