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

Changes from orignal

• Font Parser & Glyph shaper are abstracted to their own interface
• Font face parser info encapsulated in parser_info struct.
• 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

TODOs

Thirdparty support:

• Setup freetype, harfbuzz, depedency management within the library

Documentation:

• Pureref outline of draw_text exectuion
• Markdown general documentation

Content:

• Port over the original demo utilizing sokol libraries instead
• Provide a sokol_gfx backend package

Additional Features:

• Support for freetype
• Support for harfbuzz
• 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
• Allow curve_quality to be set on a per-font basis

Optimization:

• 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
  • 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
    • Each should have their own?
      • draw_list
      • draw_layer
      • atlas.next_idx
      • glyph_draw_buffer
      • shape_cache
    • This would need to converge to the singlar draw_list on a per layer basis (then user reqeusts a draw_list layer there could a yield to wait for the jobs to finish); if the interface expects the user to issue the commands single-threaded unless, we just assume 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)