A camera could only show the whole scene, so a HUD drawn in the world
would run through a camera shader (#299) with everything else. Render
layers say which cameras see an object, and overlay cameras draw their
own picture over the main one.
- The project has a list of up to 16 render layers, edited in Project
settings next to the collision layers. It is a list of its own, read
by the same rules (`layerNamesOf`).
- Sprites, texts, tilemaps, particle sources and containers carry a row
`Render layer` under their switches. Its default `Inherit` takes the
parent's layer, at the top the first one.
- A camera has `Sees` (all layers by default) and `Overlay`. The main
camera is the first one switched on without Overlay, so two plain
cameras still draw through the first one only.
- Every view through a camera keeps only what that camera sees and lays
one see-through view per overlay camera over itself. That view is a
`WorldViewport` of its own, handed its view and frame from below.
- An overlay is fitted into the main camera's whole picture without
distortion. One of the same size and zoom covers it exactly.
- `z` sorts within one camera only. The pictures lie on top of each
other as a whole, which is what a shader per camera (#299) needs.
- The Game tab's preview now collects the scene once per redraw. Before
it collected it twice, with the cameras it would have been five times.
- `SetCollisionLayersCommand` became `SetLayerNamesCommand`, which
takes the list it sets.
Follow-ups: #304 (the mouse through a chosen camera) and #305 (change
the render layer at run time).
Tests:
- Gate: 226 files, 3487 tests (3480 + 7)
- e2e 63 (new): 4 checks. A green overlay sprite at z -10 covers a
red main sprite at z 1000, in the preview and in the running game.
A `UI` sprite in front of the main camera and a `Default` one in
front of the overlay stay away. Without Overlay the second camera
draws nothing. The settings dialog adds a render layer at the end.
- Counter-checks: inheriting from parents switched off fails 1 unit
test. Overlays never drawn fails the two overlay checks in e2e 63.
- e2e total 1720 (1716 + 4), computed.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
