workshopsoft/ludic
2
0
Fork 0
Code Issues Pull requests Projects Releases 26 Packages Wiki Activity Actions

feat(camera): #78 deterministic Camera.zoom (Q16.16 render-time zoom)
All checks were successful
bootstrap / cfree-fixpoint (push) Successful in 22s
Details
ci / build-and-test (push) Successful in 2m15s
Details
commit-lint / conventional-commits (push) Successful in 4s
Details
docs / build-and-deploy (push) Successful in 28s
Details

Browse source 
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>
This commit is contained in:
Orkun ÇAKILKAYA 2026-09-02 06:55:37 +03:00
parent 5af5bdd060
commit 6a83c28e05
8 changed files with 14932 additions and 14780 deletions
Download patch file Download diff file Expand all files Collapse all files

37
examples/library/camera_zoom.ludic Normal file
View file

@ -0,0 +1,37 @@
# camera_zoom.ludic — the deterministic render-time camera zoom (#78). Zoom is a
# Q16.16 scale applied about the screen centre in the blit path; the world stays
# integer pixels, so lockstep / replay / world_save are untouched. Verified by
# pixel readback (Screen.pixel reads the actual framebuffer, un-transformed).
#
# Deterministic; a full run prints: 1 0 0 1 1
program CameraZoom {
# a model so the program runs the ECS and links the core runtime (the framebuffer
# + Screen.* live in runtime/native/core.ludic, spliced for an ECS program).
property Cam { z: fixed = 1.0 }
model View { Cam }
function bi(b: bool) -> int { if b { return 1 }; return 0 }
entry {
# A. no zoom: a 4x4 white box drawn at (100,100) lands at (100,100).
Screen.clear(0)
Screen.fill_rectangle(100, 100, 4, 4, 0xffffff)
print(bi(Screen.pixel(101, 101) == 0xffffff)) # 1 — box is here
print(bi(Screen.pixel(43, 83) == 0xffffff)) # 0 — nothing here yet
# B. 2x zoom about the screen centre (160,120): (100,100) maps to
# ((100-160)*2+160, (100-120)*2+120) = (40, 80), size 4 -> 8, so the box
# now covers x 40..48, y 80..88 and has left (101,101).
Screen.clear(0)
Camera.zoom(2.0)
Screen.fill_rectangle(100, 100, 4, 4, 0xffffff)
print(bi(Screen.pixel(101, 101) == 0xffffff)) # 0 — moved away
print(bi(Screen.pixel(43, 83) == 0xffffff)) # 1 — scaled to here
# C. zoom back to 1.0 restores the byte-identical un-zoomed blit.
Screen.clear(0)
Camera.zoom(1.0)
Screen.fill_rectangle(100, 100, 4, 4, 0xffffff)
print(bi(Screen.pixel(101, 101) == 0xffffff)) # 1 — normal again
}
}