gl-type

Simple Freetype font rendering in OpenGL with a single vertex buffer and texture.

Only horizontal, left-to-right rendering is currently supported.

Installation

This repository is a Chicken Scheme egg.

It is part of the Chicken egg index and can be installed with chicken-install gl-type.

Requirements

srfi-1
srfi-13
srfi-14
freetype
gl-utils
miscmacros
epoxy

Documentation

[procedure] (load-face PATH SIZE [char-set: CHAR-SET] [mode: MODE])

Load the font face given by the Freetype-openable file pointed to by PATH with a size of SIZE pixels. CHAR-SET is the SRFI 14 character-set that should be loaded, defaulting to char-set:graphic. Any non-graphical characters in the set will waste space. MODE is the mode in which the font should be rendered and should be one of #:normal (the default) – for normally hinted, anti-aliased rendering – or #:mono – for monochrome (aliased) rendering. Returns a face record.

[record] face
[procedure] (face? FACE)
[procedure] (face-atlas FACE)
[procedure] (face-char-set FACE)
[procedure] (face-height FACE)

The record type returned by load-face.

[procedure] (string-mesh STRING FACE [line-spacing: SPACING] [max-width: MAX-WIDTH] [x: X] [y: Y] [mesh: MESH])

Render the given STRING into a gl-utils mesh with the provided FACE. SPACING is multiplied by the standard line advancement – a smaller spacing results in less space between successive lines – defaults to 1.3. If MAX-WIDTH is provided, the string will be word-wrapped such that it does not exceed the given width. X and Y may be given to provide an offset to the rendered string’s origin. MESH may be supplied in order to reuse a mesh previously created with string-mesh. When MESH is supplied, the number of graphical characters (non-whitespace characters in the char-set of FACE) in STRING must be equal to or less than the number of graphical characters in the string used to create MESH.

Strings are rendered with the upper-left corner of the text at the origin, with the dimensions of the mesh set in pixels. The mesh that is created has vertex attributes position – a 2 element #:float – and tex-coord – a 2 element normalized #:ushort, and #:ushort indices.

[procedure] (string-width STRING FACE)

Returns the width, in pixels, of the STRING if it were rendered with FACE. Any non-graphical characters other than #\space will be ignored.

[parameter] (pixel-density-ratio)

Used to control the resolution at which fonts are rendered, defaulting to 1: each pixel unit corresponds to one display pixel. For most “Retina” displays a value of 2 should be used: each pixel unit corresponds to two display pixels.

Examples

See the examples directory.

Version history

Version 0.4.0

Maintenance given to Kooda
Port to CHICKEN 5

Version 0.3.0

27 September 2014

Add support for high density displays

Version 0.2.0

23 December 2014

string-mesh accepts keyword mesh argument

Version 0.1.0

Initial release

Source repository

Source available here

Bug reports and patches welcome! Bugs can be reported to kooda@upyum.com

Authors

Alex Charlton

Adrien (Kooda) Ramos

License

BSD

kdltr / gl-type