ludic/changes/camera-zoom.md
Orkuncakilkaya 6a83c28e05
All checks were successful
bootstrap / cfree-fixpoint (push) Successful in 22s
ci / build-and-test (push) Successful in 2m15s
commit-lint / conventional-commits (push) Successful in 4s
docs / build-and-deploy (push) Successful in 28s
feat(camera): #78 deterministic Camera.zoom (Q16.16 render-time zoom)
The #78 investigation rejected hardware f32/f64 for the coordinate types
(they would desync lockstep/replay/save) and identified camera zoom as the
one genuinely-missing render feature. Ship it: Camera.zoom(scale) scales the
whole view about the screen centre by a Q16.16 factor, threaded through the
same two framebuffer chokepoints (rt_put_px/rt_fill_rect) that carry the
camera offset, so it composes with Camera.set/follow/shake. Gated by an
internal rt_cam_zoomed flag so a game that never zooms renders byte-for-byte
identically (golden renders unchanged); Camera.zoom(1.0) turns it back off.
The world coordinate types stay integer px + Q16.16 velocity, so it's a pure
render-time transform and itself deterministic.

Example examples/library/camera_zoom.ludic (pixel-readback verified),
docs page, RFC updated (docs/RFC-POSITION-TYPES.md). Full suite 105/0,
fixpoint holds.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-09-02 06:55:37 +03:00

1 KiB

bump: minor type: feat Deterministic camera zoom (#78) — Camera.zoom(scale) scales the whole view about the screen centre by a Q16.16 factor (1.0 = none, 2.0 = 2x in, 0.5 = out). It rides on the same two framebuffer chokepoints (rt_put_px / rt_fill_rect) that already carry the camera offset, so it composes with Camera.set/follow/shake, and it is a render-time transform — the world coordinate types stay integer pixels + Q16.16 velocity, so lockstep, replay and world_save are untouched, and the zoom itself is deterministic. Gated by an internal rt_cam_zoomed flag so a game that never zooms renders byte-for-byte identically (golden renders unchanged); Camera.zoom(1.0) turns it back off. This is the concrete outcome of the #78 position-types investigation (docs/RFC-POSITION-TYPES.md), which rejected hardware floats for the deterministic coordinate core and identified zoom as the one genuinely-missing render feature. Example: examples/library/camera_zoom.ludic (pixel-readback verified).