bi-09 step 02 — Property trees, and measuring the payoff

Goal

Build the data structure that makes cheap animation possible, then prove it by removing it.

Tasks

  1. Add a transform tree. Represent a translated subtree as a node reference, not by baking coordinates into display items.
  2. Raster the display list to a canvas.
  3. The payoff experiment. Animate a subtree two ways: (a) change layout position and re-record; (b) change only a transform node. Measure both. Report exactly which stages each skips.
  4. Remove the property tree. Bake transforms into display items and re-run the experiment. Show that the cheap path is now impossible — not merely slower.
  5. Write the pipeline explanation of why transform is cheap without using the word GPU.

Done when

  • Stage-3 measurements recorded, with skipped stages named
  • Baked-transform variant proves the cheap path impossible
  • A GPU-free explanation written, that also predicts why filter: blur() is expensive