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extract the world<->widget transform into WorldCoordinates

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mlangkabel
2026-08-05 19:39:47 +02:00
parent 4f7fdb8a4c
commit 2af09d9eb1
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@@ -357,9 +357,10 @@ Sim and UI run on the same thread for v1. `paintEvent` reads sim state directly
### Coordinates and Scrolling
- `GameWorldView` holds a continuous `scrollXTiles` (float). A / D input pans this smoothly (REQ-UI-SCROLL).
- At the start of `paintEvent`, a single `painter.translate(-scrollXTiles * tilePx, 0)` maps world tile units into widget pixels (`tilePx = 20`, per REQ-GW-TILE-SIZE).
- Mouse input converts the other way: `worldX = mouseX / tilePx + scrollXTiles`; apply `floor` for a tile. Asteroid tiles (`x < 0`) need no special casing — they share the coordinate system with space tiles.
- `GameWorldView` holds a continuous `scrollXTiles` (float), the world X at the *center* of the viewport. A / D input pans this smoothly (REQ-UI-SCROLL) at a position-dependent speed (REQ-UI-SCROLL-SPEED).
- The world↔widget transform itself lives in `WorldCoordinates` (`lib/core/`), not in the view. It is an immutable value built from the viewport size, the world height, and the scroll center; `tilePx` is derived so the world height fills the viewport (REQ-GW-TILE-SIZE) rather than being fixed. Being a plain value with no Qt Widgets dependency, it is unit-tested (`WorldCoordinatesTest`) even though the widgets around it are not.
- `GameWorldView::getCoordinates()` builds one per frame in `paintGL` and per event in the mouse handlers, and passes it down: every world-space `draw<X>` takes a `const WorldCoordinates&`, while the screen-space draws (vignette borders, replay overlay, debug text) take none. The snapshot is deliberately never cached in a member — a resize or a scroll would silently invalidate it.
- Conversions are per-call arithmetic rather than a `painter.translate`, because hit-testing needs the inverse (`widgetToWorld` / `widgetToTile`, flooring for a tile) as often as drawing needs the forward direction. Asteroid tiles (`x < 0`) need no special casing — they share the coordinate system with space tiles, which is why the flooring must not be truncation.
### Culling