fix(text): draw word-granularity units with the tracking they were laid out with - #208
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The cell alpha oscillated over 0.10..1.00, so a cell never actually went out. A lattice whose cells only dip to a tenth still reads as a fixed field of permanent dots, just dimmer — which is not what an animated texture is for. 0.5 + 0.5 * sin gives the full 0 → 1 → 0. The phase still comes from each cell's own hash, or the whole field blinks in unison. The test pins the range rather than the fact that something moves: it samples 400 instants and asserts the floor goes under 0.01 and the ceiling over 0.99. "It animates" and "it reaches zero" are different claims.
…t a corner Measured on a reference piece, over 15 frames (0.5 s): the right and top edges stay pinned to the frame while the left travels 2160 -> 0 and the bottom 1480 -> 2152. Both moving edges advance at once, and the incoming scene sits still behind the growing window — it is uncovered, not pushed. None of the thirteen existing types expresses that. wipe_* moves a single full-width band on one axis, iris is a circle, and slide translates both frames together. The closest approximation, a dissolve, loses the whole gesture. `corner` selects which two edges are pinned: top_right (the measured default), top_left, bottom_right, bottom_left. It is inert for every other type. Five tests pin the geometry rather than describe it: the anchored edges never move, the travelling ones open monotonically in the direction the corner names, the ends are empty and full, each corner anchors its own pair, and out-of-range progress clamps instead of inverting the rectangle — an inverted rect clips to nothing and the transition would silently look like a cut.
…id out with
A word-granularity char animation advances its cursor by the width measured
*with* letter-spacing, but apply_text_anim_preset drew every unit at 0.0. With
negative tracking the glyphs then overrun their slot by |tracking| * (chars-1)
and eat into the following space:
letter-spacing: -2, 54 px, granularity: word
"without a maintenance window" -> "withouta maintenancewindow"
The overrun is a fixed number of pixels, so it only shows once it approaches a
space's width: invisible on 143 px display type, fatal at 54 px. Isolated by
rendering the same string five ways — neither word granularity nor negative
tracking does it alone, only the pair.
The character path passes 0.0 explicitly: a single character has no internal
tracking, and stating it keeps the two branches from drifting apart.
Also adds rules/terminal-product-register.md, the measured visual register this
was found while reproducing.
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What
A word-granularity char animation advances its cursor by the width measured with letter-spacing, but
apply_text_anim_presetdrew every unit at0.0. With negative tracking the glyphs overrun their slot by|tracking| * (chars - 1)and eat into the following space.How it hides
The overrun is a fixed number of pixels, so it only shows once it approaches the width of a space:
Which is why the same register renders correctly on display type and breaks on the smaller opening line.
Isolated by rendering one string five ways — no animation at tracking 0 and −2, word granularity at 0 and −2, and a plain
fade_inat −2. Only the pair (word granularity × negative tracking) reproduces it.Fix
Thread the tracking into
apply_text_anim_presetand draw with it. The character path passes0.0explicitly rather than by omission: a single character has no internal tracking, and saying so keeps the two branches from drifting apart.What I could not do
I have no automated test for this. I wrote three, and all three passed in both the fixed and the broken state — a test that cannot fail on the bug it targets is worse than none, so I removed it rather than ship advertised coverage that does not exist. The overall ink span does not move (the cursor positions are unchanged), and the inter-word gap measurement I tried could not separate word gaps from letter gaps reliably at this size. The fix is verified visually, on a five-case probe, in both directions.
Worth a follow-up by someone who knows the text pixel-test helpers better than I do.
Also in this PR
rules/terminal-product-register.md— the measured visual register this was found while reproducing: palette, the two type scales (with the stem-to-cap method for picking a weight, which is what caught a wrong reading here), the composed terminal pane, beat proportions, and the traps collected along the way.cargo test --workspacegreen,cargo fmt --checkandcargo clippy --all-targets -- -D warningsclean.