SectrPrototype/code/font/vefontcache

VE Font Cache : Odin Port

This is a port of the VEFontCache library.

Its original purpose was for use in game engines, however its rendeirng quality and performance is more than adequate for many other applications.

See: docs/Readme.md for the library's interface.

Building

See scripts/Readme.md for building examples or utilizing the provided backends.

Currently the scripts provided & the library itself were developed & tested on Windows. There are bash scripts for building on linux (they build on WSL but need additional testing).

The library depends on freetype, harfbuzz, & stb_truetype to build.
Note: freetype and harfbuzz could technically be gutted if the user removes their definitions, however they have not been made into a conditional compilation option (yet).

Changes from orignal

• Font Parser & Glyph shaper are abstracted to their own warpper interface
• ve_fontcache_loadfile not ported (ust use core:os or os2, then call load_font)
• Macro defines have been coverted (mostly) to runtime parameters
• Support for hot_reloading
• Curve quality step interpolation for glyph rendering can be set on a per font basis.

TODOs

Additional Features:

• Support for freetype (WIP, Currently a mess... and slow)
• Add ability to conditionally compile dependencies (so that the user may not need to resolve those packages).
• Ability to set a draw transform, viewport and projection
  • By default the library's position is in unsigned normalized render space
  • Could implement a similar design to sokol_gp's interface

Optimization:

• Check if its better to store the glyph vertices if they need to be re-cached to atlas or directly drawn.
• Look into setting up multi-threading by giving each thread a context
  • There is a heavy performance bottleneck in iterating the text/shape/glyphs on the cpu (single-thread) vs the actual rendering (if doing thousands of drawing commands)
  • draw_text can provide in the context a job list per thread for the user to thenk hookup to their own threading solution to handle.
  • Context would need to be segregated into staged data structures for each thread to utilize
    • This would need to converge to the singlar draw_list on a per layer basis. The interface expects the user to issue commands single-threaded unless, its assumed the user is going to feed the gpu the commands & data through separate threads as well (not ideal ux).
  • How the contexts are given jobs should be left up to the user (can recommend a screen quadrant based approach in demo examples)

Failed Attempts:

• Attempted to chunk the text to more granular 'shapes' from draw_list before doing the actual call to draw_text_shape. This lead to a larger performance cost due to the additional iteration across the text string.
• Attempted to cache the shape draw_list for future calls. Led to larger performance cost due to additional iteration in the merge_draw_list.
  • The shapes glyphs must still be traversed to identify if the glyph is cached. This arguably could be handled in shape_text_uncached, however that would require a significan't amount of refactoring to identify... (and would be more unergonomic when shapers libs are processing the text)