dlubal-software / osgpairo

A OpenSceneGraph NodeKit, that merges osgPango and osgCairo, that wrap Pangocairo for usage in OpenSceneGraph

Introduction

osgPairo is a NodeKit for OpenSceneGraph for high quality font rendering that combines the osgPango and osgCairo NodeKits into a single NodeKitt to make it easier to integrate with applications, including ones that use other versions of osgPango and osgCairo.

Technical

osgPairo renders fonts using the following setup:

• A variable number of "layers" (textures) are allocated, per-font, that will eventually ALL be combined on a textured quad to form the final resultant glyph. You could think of this as a kind of osgPPU pipeline, if you're familiar with that fantastic nodekit. :)
• Each layer is drawn to using a polymorphic API and the Cairo library. The overridden method in your subclass can do virtually ANYTHING with ANY layer, and for demonstration some standard font effects are provided: shadows, outlines, bitmap fills, etc.
• Each layer is packed into an array that is fed to the current state, along with a global alpha value and a color value (per-layer) that can either be ignored--if your layers include color data--or instead blended with the alpha value provided in the texture; in fact, this is the most common osgPairo usage: the GL_ALPHA texture drawn by Cairo is modulated by a color value specified in Pango markup to produce the final color.
• Finally, a GLSL shader comes along and does the final compositing. Code is provided inside of osgPairo to help you generate these shaders (or, preferably, just use the ones we provide!), but you're welcome to "roll your own" as well.

Videos

And finally, we have a (somewhat older) video of osgPairo + osgAnimation demonstrating the VERY IMPORTANT fact that each glyph and its associated quad are readily available to the user for direct, immediate manipulation.

VIDEO-001 (YouTube)

Building

OSG, and you'll also need one of these:

64bit GTK+ Libs

32bit GTK+ Libs

Authors

Author	Contact	Contributions...
Jeremy Moles	[email protected]	Lead hacker/developer
Jaromir Vitek	[email protected]	Professional hacking
Cedric Pinson	[email protected]	library exercise and the creation of the osgAnimation video
Serge Lages	[email protected]	Bug fixes
Sergey Kurdakov	[email protected]	Bug fixes
Robert Osfeild	[email protected]	Feature additions, Merge into osgPairo Build improvements

TODO

• Add Glyph loading from images/metadata; ESPECIALLY DISTANCE FIELD TEXT!
• Add the ability to dump the caches in one large PNG, instead of a bunch of pngs. This should be a "developer debug" image.
• Add a wrapper around having to use <span> all the time; perhaps a kind of ostream<< clone.