Chapters 17 and 18 read as a code review of a finished listing: they explained
why each decision had been made, walked through the project's own history, and
led with what had once been broken. A reader who wanted to build the game got
the reasoning and had to reconstruct the program.
Both are now step-by-step. Each opens with a picture of the finished game and a
bullet list of the steps, each bullet is a section, and each section states its
goal, shows the code, and says how to check it. Chapter 17 is sixteen steps and
Chapter 18 is thirteen, and the last of each is the assembly: the order of the
file, the full declaration block, and the routines the earlier steps referred to.
Project history is gone -- it belongs in Chapter 14 and in git -- and where a
listing has to do something awkward, the tutorial shows how first and names the
`TODO.md` item that will make it unnecessary second.
**Three defects had no entry anywhere**, which the rewrite found by trying to
state each rule as a rule. §6 item 35: `a - b + c` computes `a - (b + c)`,
because `subtraction()` sits above `addition()` as its own precedence level and
the inner loop eats the `+`. Item 36: only one unparenthesised `AND` or `OR` is
matched, which is item 12's `if`-where-`while` on the one operator pair item 12
did not reach. Item 37: a `GOTO` out of a `FOR` or a `DO` leaks the loop's scope,
so a main loop written that way stops on the thirty-second lost life -- which is
why both games are built out of `LABEL` and `GOTO`, and it is a workaround rather
than a preference. Chapter 3 gains the identifier rule the third trial ran into:
there is no underscore in a name, and the error says `UNKNOWN TOKEN _`.
**`tools/screenshot.c` learned to draw the text layer**, behind a new `text=1`
fence attribute, because Chapter 17's game is characters in the grid and a figure
without that layer is two sprites on black. It opens the bundled font at the size
the standalone frontend uses, so a figure's cell size is the reader's cell size,
and it uses the akgl sink alone rather than a tee so the program's output lands in
the picture instead of on the stdout the caller reads to decide a figure failed.
Both new figures -- `breakout-game.png` and `breakout-game-artwork.png` -- are
generated from listings in the chapters like every other one.
Verified by handing each chapter, alone, to an agent on a much smaller model and
telling it to build the game from the tutorial text with the `examples/` tree off
limits. The first pass scored 3.5 and 3 out of 10 and named what was missing:
routines referred to but never shown, the third level layout, the sprite `DATA`,
the font table, edits to earlier routines that were never marked as edits. Those
are now in. The second pass built a 658-line Chapter 17 game that plays itself
for ninety seconds with the score at 1890 and no error line, and the third built
a 1053-line Chapter 18 game with 61 labels, no invented routines, no gaps found,
and forty seconds clean. 9/10 and 8/10.
One real bug in the new prose, caught in review: Chapter 18's `HITBAR` did not
set the `HIT#` that `BALLPADDLE` reads to decide whether the paddle already
caught the ball. Both suites green in both configurations, `docs_examples` and
`docs_screenshots --check` pass.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EwxGB6TdoVvZ11KQQME9cL
0.5.0 gives every exported symbol the akgl_ prefix, which is the first libakgl
release to break this project's source rather than only its ABI. The soname goes
to libakgl.so.0.5 and include/akbasic/akgl.h asserts the floor.
What moved here: akgl_render_bind2d is akgl_render_2d_bind,
akgl_sprite_sheet_coords_for_frame is akgl_spritesheet_coords_for_frame, the
renderer, camera and window globals carry the prefix, and _akgl_renderer and
_akgl_camera are akgl_default_renderer and akgl_default_camera.
The renames were applied by site rather than by pattern, because renderer is also
a parameter name in src/sprite_akgl.c and a struct member throughout
src/frontend_akgl.c -- a substitution would have rewritten both without a word.
That is the same trap upstream describes hitting, and it is worth knowing that
the defect behind the rename was not cosmetic: an exported global called renderer
collided with a test's own variable, the executable's definition preempted the
library's, and every texture load in that suite failed while the suite passed.
0.5.0 also fixes libakgl defect 26, which was one of the two reasons
src/sprite_akgl.c installs its own renderfunc: akgl_actor_render took its
destination height from the sprite's width, drawing a 24x21 Commodore sprite as a
24x24 square. The renderfunc stays, because the other reason has not moved -- an
actor carries one scalar scale and SPRITE has separate x- and y-expand bits --
but the comments and TODO.md deviation 40 no longer claim a defect that is fixed.
Every documentation figure re-renders byte-identical under the new library, which
is what says the sprite and drawing paths did not move underneath them.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Chapters 6 and 8 described what a verb draws in prose. Eight figures now show
it, and each one is produced by running the BASIC listing printed immediately
above it -- so a picture cannot drift away from the code beside it, which is the
way a screenshot goes wrong and the way nothing notices.
tools/screenshot.c is a second SDL host, much smaller than the frontend: dummy
video driver, software renderer, run to completion, read the target back, write
a PNG. It draws no text layer on purpose, so a READY in the corner is not noise
in a figure about BOX and no font has to be resolved.
tools/docs_screenshots.sh reads the new screenshot=NAME fence tag straight out
of the markdown. size=WxH is the second tag, and SCALE's figure uses it: the
point being made is a 320x200 listing filling a larger window, which cannot be
made on a 320x200 surface.
Two gates, answering different questions. docs_examples fails a tagged block
with no image, in both configurations, so a figure cannot be added and
forgotten. docs_screenshots -- a CTest, AKGL build only -- re-renders every
figure and compares byte for byte, so a listing edited without regenerating
fails. Only the second catches a stale picture.
The PNGs are checked in because a reader on the forge has no build tree, and
docs/images/README.md says loudly that they are generated. Regenerating is never
part of a build: the target is run deliberately, so a make cannot put eight
binary diffs in front of whoever ran it.
Drawing the BOX figure caught a defect in TODO.md itself. Deviation 16 claimed
in bold that BOX fills on a negative angle while its own paragraph said the fill
was filed rather than implemented. BOX cannot fill, and filled_rect is reached
by no verb as a result.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
