gltext

Note: This package is experimental and subject to change. Use at your own discretion.

The gltext package offers a simple set of text rendering utilities for OpenGL programs. It deals with TrueType and Bitmap (raster) fonts. Text can be rendered in various directions (Left-to-right, right-to-left and top-to-bottom). This allows for correct display of text for various languages.

The package supports the full set of unicode characters, provided the loaded font does as well.

TODO

• Have a look at Valve's 'Signed Distance Field` techniques to render sharp font textures are different zoom levels.

  • SIGGRAPH2007_AlphaTestedMagnification.pdf
  • Youtube video

  More links to info in the youtube video description. An alternative might be a port of GLyphy

Known bugs

• Determining the height of truetype glyphs is not entirely accurate. It is unclear at this point how to get to this information reliably. Specifically the parts in LoadTruetype at truetype.go#L54+. The vertical glyph bounds computed by freetype-go are not correct for certain fonts. Right now we manually offset the value by added 4 to the height. This is an unreliable hack and should be fixed.
• freetype-go does not expose AdvanceHeight for vertically rendered fonts. This may mean that the Advance size for top-to-bottom fonts is incorrect.

Dependencies

This packages uses freetype-go which is licensed under GPLv2 e FTL licenses. You can choose which one is a better fit for your use case but FTL requires you to give some form of credit to Freetype.org

You can read the GPLv2 and FTL licenses for more information about the requirements.

Usage

go get github.com/go-gl/gltext

Refer to go-gl/examples/gltext for usage examples.

License

Copyright 2012 The go-gl Authors. All rights reserved. Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.