Render with WebGL instead of SVG?

[ianmackenzie]

• High performance
  • Especially for things like complex Region2d values with complex curves that have to be linearized
• Full control (fewer browser quirks!)
• Easy to do hatching etc. using custom fragment shaders
• Can support Z levels
• Picking, dragging etc. infrastructure could be shared with elm-3d-scene
• Would need to implement font support - published preprocessed font files to some sort of CDN?
  • Convert fonts to splines + baseline/spacing etc. info in JSON format

[ianmackenzie]

Potential issue: having a Drawing2d.pack function that combined vertex buffers could change draw order, which in turn could lead to issues with what primitives are drawn on top of which others. Could this be solved by doing something like restricting user Z-values to Int values, and using Float values internally?

Alternate approaches:

• Mandate use of Z value, behavior is undefined if Z value is tied
• Only merge meshes where safe? Pretty restrictive...
• Don't support Drawing2d.pack

[ianmackenzie]

Good initial approach:

• Lines, circles/arcs and quadratic splines are rendered exactly (using https://developer.nvidia.com/gpugems/GPUGems3/gpugems3_ch25.html for quadratic splines)
  • Dots, circles, arcs, rounded rectangles and TrueType text can be rendered pixel-perfectly
• Cubic splines, elliptical arcs and other curves are rendered via linearization
  • Could add specialized support for cubic splines and/or elliptical arcs in the future
• Just support round end caps initially, to avoid more complex/expensive math associated with miter/bevel

[ianmackenzie]

Potential drawback: could lead to lower performance for complex scenes if meshes are not cached between view calls (especially since this may not be obvious for things like rendering curves which are implicitly converted to high-resolution polylines). May be nicer to stick to virtual DOM diffing by using SVG internally, especially since then it should be possible to support lazy.