Simple Freetype font rendering in OpenGL with a single vertex buffer and texture.
Only horizontal, left-to-right rendering is currently supported.
- (load-face PATH SIZE [char-set: CHAR-SET] [mode: MODE]) procedure
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.
- face record
- (face? FACE) procedure
- (face-atlas FACE) procedure
- (face-char-set FACE) procedure
- (face-height FACE) procedure
The record type returned by load-face.
- (string-mesh STRING FACE [line-spacing: SPACING] [max-width: MAX-WIDTH] [x: X] [y: Y] [mesh: MESH]) procedure
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.
- (string-width STRING FACE) procedure
Returns the width, in pixels, of the STRING if it were rendered with FACE. Any non-graphical characters other than #\space will be ignored.
- (pixel-density-ratio) parameter
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.
See the examples directory.
27 September 2014
- Add support for high density displays
23 December 2014
- string-mesh accepts keyword mesh argument
- Initial release
Source available on GitHub.
Bug reports and patches welcome! Bugs can be reported via GitHub or to alex.n.charlton at gmail.