Procedural vector data and attributes design considerations

[Keavon]

Partially related to #2522, #2309, #1832, #1834, #950.

• Data-oriented design (struct of arrays)
• Harmony with Vello’s GPU-based pipeline
• SIMD and compute shader friendliness
• Sequential (like SVG) vs. index buffer (like OBJ) approach
• Short-term: vector paths (SVG-style open or closed paths)
• Long-term: vector meshes (points, segments, and regions)
• Segments representing any curve spline type
• Basing paths around segments or manipulator groups
• Relationship between anchors and handles
• Columns for attributes (and custom attributes for passing along any info like color palette or other variables)
• Open or closed faces
• Subpaths
• Fill rule
• Winding order
• Styling with fill
• Styling with stroke
• Stroke taper
• Stroke being affected by parent groups that impose a stretch/skew transformation
• Stroke caps/joins varying per-point
• Avoiding cloning per node
• Integration of monadic attributes into the graph
• Copy on write attributes
• Lazy evaluation of whole attributes (columns) or ranges (rows)
• Propagating parametric modeling constraint relationships
• Be a superset of a 3D mesh (including a Z axis) to support 3D to 2D vector flattening
• Vector mesh depth sorting in the event of overlapping faces
• Support for a bisection style drawing approach shown in https://www.youtube.com/watch?v=EZLEkhxiw9o
• Support for a Shape Builder tool and Trim tool where you draw cuts through segments

[Keavon]

I originally wrote this down January 2024, but I've transferred this here now for easier reference.