Drawing an outline by hand for every frame of a sheet is slow, and the
outline mostly follows the opaque part of the image anyway. The texture
tab now traces it: one click, a corner budget, and every Frame
collision collider and tile using that frame blocks with the result.
- "Generate collision..." sits in the texture tab header and is off
while the texture has no frames.
- The dialog has Max points (default 8, 3 to 64), Solid from ... %
alpha (default 50) and All frames of the texture. A live line says
what Generate will write, and Generate stays off when nothing is
solid enough.
- traceCollision walks each island of solid pixels along the pixel
edges, then drops the least important corners until at most N are
left and no stair step remains. A slope becomes one straight edge.
- An outline never crosses itself. Where the image would force that,
the island's convex hull is taken instead.
- Crumbs under 1 % of the frame area are dropped unless they are the
only island. Holes are not reproduced.
- Existing outlines are replaced. One frame or all frames is a single
undo step.
- TextureLibrary hands out the sheet's RGBA data, and a pure function
cuts a frame's region from it.
Findings:
- The wedge in the e2e fixture gets 4 corners, not 3. Its tip is one
pixel wide in the image, and that real edge stays while corners are
still free.
Tests:
- ./check.sh: 131 files, 1941 tests, CHECK EXIT 0 (was 130 / 1931).
- 10 new unit tests in tests/core/trace-collision.test.ts, including
150 random shapes that must all be valid and within the budget.
- GM_STEPS=42, freshly seeded: ALL PASSED, 20 checks (was 16).
- Three counter-probes bite: no hull fallback, no stair threshold,
dialog ignoring the alpha threshold.
- Check sum 1202 in README is computed (1198 + 4), CI measures it.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Issue #193 asked where friction, bounciness and density of a tile
live. Tiles had a fixed surface (friction 0.5, bounciness 0) and a
collider could not use the outline drawn on a texture frame (#141).
Both gaps are closed here.
- A collider has a fifth shape "Frame collision" with a Frame row.
The frame is picked like a sprite's texture and stored as the
value 'frame'.
- The shape is linked, not copied. Redrawing the outline in the
texture tab changes every collider using that frame, in the editor
and on the next play.
- The frame centre sits on the collider origin, one image pixel is
one unit. The shape turns, scales and mirrors like any other.
- Every outline ring blocks. Each ring is split into convex parts the
same way a polygon is.
- Without a frame, with a whole texture or with a frame that has no
outline, the collider is drawn red as a box and blocks nothing.
- Move, Rapier, raycast, detection, hit test, drawing and footprint
all resolve the frame. At runtime an entity looks the frame up
live in the current project.
- A tile has Friction and Bounciness next to Solid and One-way. The
rows only show when Solid is on. Defaults and mixing rules match
the collider. Density is left out because a tilemap never moves.
- Tilemap cells are grouped by surface as well as by one-way angle.
Ice and stone never merge into one rectangle, and every cell brings
its surface to Move and Rapier.
Findings:
- A tile with a collision scale below 1 is no longer flush with a
neighbour of another surface. It is inset there like at an open
side, the same as next to one-way tiles today.
- A bounce test first measured 0.84. The ball had landed on the hero
at the origin, not on the tile. On the tile it measures 0.993.
Tests:
- ./check.sh: 130 files, 1931 tests, exit 0 (was 129 / 1917).
- 14 new unit tests in tests/core/surface.test.ts. The Move tests run
against the editor run and the physics system.
- 3 new e2e checks: 40l (surface rows follow Solid), 42e (collider
has frame size, a walker climbs the slope in the frame).
- GM_STEPS=1-8,39-43 freshly seeded: ALL PASSED, 376 checks.
- Three counter-probes bite: Move ignores the tile surface (2 fail),
Rapier ignores it (1 fails), frame shape falls back to a box
(5 fail).
- Check sum 1198 is computed (1195 + 3), the full run belongs to CI.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
adminandClaude Opus 5