Both examples gain --screenshot PATH and --screenshot-frame N. The capture sits
between the world being drawn and the frame being presented, because
SDL_RenderPresent is where the target stops being readable, and it works under
the dummy video driver and the software renderer like the rest of the headless
path does.
`cmake --build build --target docs_game_figures` regenerates
docs/images/sidescroller.png and docs/images/jrpg.png by running each game to a
chosen frame. Same contract as docs_screenshots: deliberate, never part of a
build, because the PNGs are tracked. There is no --check counterpart, and the
target says why -- the sidescroller drives its physics from the wall clock, so a
byte comparison would fail for reasons that have nothing to do with the
documentation.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KzBDV2fqgnUAcqCKqKvc71
collision.c was 383 lines that re-implemented akgl_physics_simulate's own
arithmetic, because movementlogicfunc runs before gravity, drag and the move
and so had to predict where the actor would end up. The whole file goes. What
replaces it is three lines in main.c, a shape on the player and the blob, and a
`collidable` property on the map's terrain layer -- which also retires
SS_TERRAIN_LAYER_ID, a compiled-in layer id that broke whenever somebody
reordered layers in Tiled.
grounded stays a probe rather than becoming a contact test. A contact says
something pushed back this step; grounded asks whether there is a floor to push
off, and that stays true through the frame after landing. The blob keeps its own
wall and ledge probes for the same reason: the resolver does not say which side
of the blob it was pushed from, and says nothing at all about a floor that is
missing.
The summary line now carries the player's resting position, because exiting 0
was not evidence that collision ran. It reports 136.0,160.0 grounded after 240
autoplay frames -- feet at y=192, flush on the surface of terrain row 12.
The tutorial's collision section is rewritten around the library's, keeping the
quarter-of-a-pixel story as what a predicting resolver costs. The docs harness
learns `json excerpt=`, so the map property the chapter quotes is checked
against the map.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KzBDV2fqgnUAcqCKqKvc71
examples/sidescroller and examples/jrpg are complete programs, built with the
library and exercised headless by ctest. The chapters quote them with
`c excerpt=examples/...` blocks rather than restating the code, so a chapter
cannot drift from a program that compiles -- the excerpt check fails the moment
the source moves. 34 excerpts in one chapter, 21 in the other.
The two are complementary. The sidescroller is the physics tutorial: gravity, a
jump, coins, hazards. The JRPG is the content-pipeline tutorial: a town map,
NPCs spawned from map objects, four-way per-facing animation, a text box, a
follower.
Both smoke tests drive real SDL_Events through akgl_controller_handle_event and
step the physics clock at a fixed 1/60s rather than sleeping, so a scripted run
is deterministic and finishes in under five seconds.
Writing them is what turned up most of the defects recorded in the next commit,
because a game exercises paths a unit test does not. Each workaround says in the
chapter which library gap forced it:
- collision is written in a custom movementlogicfunc, because
akgl_physics_arcade_collide raises AKERR_API and akgl_physics_simulate never
calls collide at all;
- the sidescroller cancels the step's own gravity when it blocks downward,
because otherwise a quarter-pixel of penetration makes the *horizontal* sweep
report blocked and the character walks backwards a tile at a time;
- both clear movement_controls_face on every map-spawned actor, because the
default facefunc leaves a stopped actor with no facing bit, no sprite, and no
draw;
- the JRPG's follower gets a renderfunc that nulls obj->parent for the duration
of the draw, because a child's offset is counted twice.
Assets are CC0 from three Kenney packs, vendored with per-pack licence text,
per-file provenance, and the geometry contract in
docs/tutorials/assets/README.md. CC0 specifically rather than merely free: a
reader who copies a tutorial into their own game inherits no obligation.
scripts/fetch_tutorial_assets.sh refreshes them in the shape
mkcontrollermappings.sh was fixed into for 0.5.0 -- it checks curl's status,
refuses a pack page that does not say CC0, verifies the archive and the staged
dimensions, and leaves the tracked bytes untouched on any failure. Both failure
paths were tested, and a no-op refresh is byte-identical.
Co-Authored-By: Claude Code <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
