7 Commits

Author	SHA1	Message	Date
Andrew Kesterson	a01554d304	Teach the artwork tutorial the converted listing ... Chapter 18 still taught the machinery the listing lost when it moved onto SOLID and the persistent drawing layer: the frame-boundary PACE routine, the flattened live list, the SSHAPE pool accounting, and the sixty lines of BALLBRICKS/TESTCELL that computed a minimum translation axis by hand. Step 8 now registers each brick with SOLID, arms COLLISION 2 and reads the contact back with RCOLLISION, including the point that costs an evening if it is missed: the BUMP mask is by sprite, and the balls are sprites 5, 6 and 7, so their bits are 16, 32 and 64. The FOR-with-equal-bounds rule that every one-item case in the chapter depends on is now stated where it is first used rather than referred to from a step that no longer exists. The listing loses six declarations orphaned by the conversion and the comment blocks that still described the captures. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EwxGB6TdoVvZ11KQQME9cL	2026-08-02 13:13:51 -04:00
Andrew Kesterson	39d1d0c80c	Stop the artwork breakout drawing its screen into two sprites ... It captured the HUD strip into sprite 1 and the whole play field into sprite 2, and its own header called them "the screen". That was never a choice: a drawing lasted one frame, so a sprite was the only thing the interpreter would redraw for nothing. Both slots are free now, and five things went with them. **`WINDOW 0, 35, 49, 36` is the first executable line.** The text layer repaints every row it owns and by default owns the whole window; moved to two rows at the bottom, it leaves the other thirty-five to the drawing verbs, and what the program draws stays. **`PACE` is gone.** It spun on `TI#` until a batch boundary so an `SSHAPE` capture would not be cut in half by a present. Nothing is captured, so a drawing spanning two batches simply arrives over two frames and the layer keeps both halves. The 256-line drawing deadline that shaped every draw routine in this listing does not apply to it any more. **The flattened live list is gone** -- `BUILDLIVE`, `BUILDROW`, `STAMPROW` and the four arrays behind them. They existed so a full-field redraw could be one stamp and an advance per brick, and a full-field redraw existed because removing one brick meant rebuilding all sixty. A broken brick is now erased in place with a blank stamp, so the field is drawn once per level and not again. **`BALLBRICKS` and `TESTCELL` are gone** -- about sixty lines that turned the ball's box into a range of candidate cells, walked them with a nested `DO`, and computed an overlap rectangle to pick an axis. `SOLID` registers each brick as the level is laid out, `COLLISION 2` fires, and `RCOLLISION` says which brick, which way out, how far, and which axis to reverse. **The `SSHAPE` pool accounting is gone.** `SHN#` counted slots because every frame's capture spent another and `GRAPHIC 5` had to throw them all away periodically; eight are now spent once and never again. Three mistakes worth recording, because each was silent: - **The bricks were registered and then immediately thrown away.** `GOSUB BUILDLIVE` sat *after* the fill loop in `SETUPLEVEL` and meant "rebuild the list of what is standing"; replaced in place by a bare `SOLID`, it meant "retire everything" and ran after all sixty had been registered. Nothing failed -- the ball simply passed through the wall. - **The handler tested the wrong bits.** `BUMP` is a mask by *sprite*, and the balls are sprites 5, 6 and 7, so their bits are 16, 32 and 64. Testing 1, 2 and 4 asked about the HUD and field sprites that no longer exist. - **The eraser stamps were undeclared**, so `SSHAPE` filled them inside `DRAWPROTOS` and they were empty everywhere else -- exactly the scope trap chapter 17 Step 3 is about, found by printing the handle inside the routine and again outside it. Verified by driving it: a copy with a tracking paddle and auto-relaunch breaks thirteen bricks in sixty seconds with no error line, and the shipped listing runs clean. Both suites green. Chapter 18 still describes the architecture this commit removed; that is the rest of section 6 item 39. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EwxGB6TdoVvZ11KQQME9cL	2026-08-02 12:58:08 -04:00
Andrew Kesterson	9e43acc0b0	Give the characters breakout its bricks as collision geometry ... `HITTEST`, `XBRICK` and `YBRICK` are gone -- about forty lines that divided pixels by cell sizes to recover a grid index, tested the ball's leading edge rather than its box, and could miss a brick clipped at the corner by seven pixels' worth of ball. In their place: sixty `SOLID` rectangles registered as the wall is built, `COLLISION 2, BRICKHIT`, and a fifteen-line handler. The handler reads better than what it replaces because it asks rather than derives. `RCOLLISION(1, 1)` is which brick -- the id is the array index plus one, so nothing is looked up. Fields 2, 3 and 4 are the way out and how far, so the ball is pushed exactly clear instead of being restored to a remembered `OX#`/`OY#`. Field 7 is which axis to reverse, which `TESTCELL` in the other game computes by hand from an overlap rectangle. `MOVEBAL` loses its two brick calls and its position backup. `KILLBR` retires the rectangle in the same breath as clearing the array element, so the next frame cannot hit a brick that is no longer drawn. **A latent defect in the target prescan had to be fixed first, and `RCOLLISION` is the first name in the language to reach it.** `src/renumber.c` walks a line character by character looking for `GOTO`, `GOSUB`, `COLLISION` and the rest, and checked only the character *after* a match -- so `RCOLLISION(1, 1)` found `COLLISION` at its second character, read the `(1,` that followed as a handler line number, and refused the whole program with "branch to line 1, which the program did not number", naming a line that contains no branch at all. It now requires a word boundary on both sides. The comment there was already right that the trailing check protects `GOTOX#`; nothing protected `XGOTO#`. `tests/unnumbered.c` covers all three shapes and TODO.md section 6 item 42 records it. The game runs ninety seconds headless with no error line and the attract mode scores 1320, so bricks are being found and broken through the new path. Chapter 17 is not updated yet -- that is the other half of section 6 item 39, and it is a bigger edit than this one. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EwxGB6TdoVvZ11KQQME9cL	2026-08-02 11:17:34 -04:00
Andrew Kesterson	1fb808f480	Rewrite the two game tutorials as instructions rather than commentary ... 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	2026-08-02 08:08:23 -04:00
Andrew Kesterson	0679c3042b	Stop the listings and their chapters stating fixed defects as fact ... You were right that this was still everywhere. The two `.bas` files carried their workarounds as present-tense statements about the interpreter -- "a name first created inside a GOSUB costs a value slot that is never handed back", "writing PAST the terminator of a short row draws nothing at all", "SSHAPE and GSHAPE ignore the subscript on a string array", "a FOR inside a BEGIN block does not survive the RETURN" -- and every one of those is now false. A comment that lies is worse than no comment, and these were the first thing anybody opening the files would read. **The characters game takes the geometry fix.** `CW# = 16` becomes `CW# = RGR(3)`, and the grid comes from `RWINDOW`, so the game fits whatever window and font the host gives it. That was the one thing in the listing that would break on a different font, and `RGR(3)` and `RWINDOW` were added to the interpreter because of it -- leaving the constant in place while Chapter 17 teaches the function was the inconsistency worth closing. `RGR(1)` still comes first so a build with no graphics device refuses by naming the device that is missing. Everything else in both listings keeps its shape and says why. Declaring every name up front, guarding loops with `GOTO`, six scalars for six brick stamps: none is forced any more and none costs anything, so they stay, with the comments marking which rules stand and which are history. The sprites header's five traps are marked FIXED where they are fixed. The chapters follow: Chapter 17 Step 2 no longer says "the listing still has `CW# = 16`", and Chapter 18's trap section is "five things that did not do what they looked like" with the two that still stand named up front rather than left to be counted. Verified: Chapter 17 Step 2's block is once again verbatim from the listing, so every quoted fragment in both chapters matches its source with no exceptions; both games run 40 seconds on the SDL frontend with no error line; both suites green in both configurations; `docs_examples` and `docs_screenshots --check` pass. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-02 06:32:48 -04:00
Andrew Kesterson	91fadf032b	Bring the tutorials back in line with the fixed interpreter ... Eleven of the thirteen defects these two games found are fixed, and the chapters that taught around them said things that are no longer true. Chapter 17: the drawing verbs are no longer invisible, they are covered by a text layer that `WINDOW` can now shrink; the cell size is `RGR(3)` and the grid is `RWINDOW`, not a hand-measured constant; a character written past a short row's end lands. Chapter 18: traps 3 and 4 -- the skipped block that broke its caller's `RETURN`, and `SSHAPE` ignoring a subscript -- become history rather than warnings, and Step 3 no longer claims a sprite is the *only* way to put a picture up, only the one that costs nothing. **Neither `.bas` listing changes, and both READMEs now say why.** The character game still writes `CW# = 16` and the artwork game still keeps six brick stamps in six scalars. What those listings are worth is being what a program written against those constraints looks like, with comments explaining what each one was avoiding -- rewriting them to pretend the problems never existed would throw that away. So Chapter 17 Step 2 shows the `RGR(3)`/`RWINDOW` form and says plainly that the listing beside it does not use it. That is the one place in either chapter where a quoted fragment is not verbatim from the game. Also: the closing pointers now say which entries are struck and which stand, and the budgets table in Chapter 18 notes that several of those budgets were tighter when the game was written. TODO.md section 9 item 3 is updated rather than struck: the `WINDOW` half is fixed, the default text area owning the whole window is not, and whether that default is right is a question rather than a defect. Verified against the fixed interpreter: both games run 45 seconds on the SDL frontend with no error line and the score climbing; both suites are green in both configurations; `docs_examples` passes and `docs_screenshots --check` re-renders all thirteen figures byte-identically; coverage is 95.0% of lines against the 90 gate, with src/variable.c at 100%; and every other quoted fragment still appears verbatim in the listing it came from. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-02 00:31:06 -04:00
Andrew Kesterson	cb0e2d0800	Add two Breakout examples and the tutorials that build them ... Two complete games in `examples/breakout/`, both 100% BASIC: `characters/` draws its wall in the text grid with two `DATA` sprites for the ball and paddle, and `sprites/` loads CC0 artwork and captures its whole screen with `SSHAPE`/`SPRSAV`. They take opposite shapes for reasons that are entirely this interpreter's, which is what the chapters are for. `docs/17-tutorial-breakout.md` and `docs/18-tutorial-breakout-artwork.md` build each one a step at a time, and end in a checklist of the rules a real program runs into: create every name before the loop starts, write a text row whole, loop with `GOTO` rather than `DO`, put the float on the left. Every trap is a runnable block with its own output rather than a claim -- the value pool dying at four thousand names, the skipped `BEGIN` block that breaks its caller's `RETURN`, `SSHAPE` ignoring a subscript, `READ`'s single cursor. Five figures, generated from the listings beside them by `docs_screenshots`, and a `breakout_art` setup so the ones that load artwork load the example's own. The character game's wall cannot be photographed -- the screenshot host omits the text layer on purpose -- so it is shown as compared output instead. `docs/07-sound.md` never said `SOUND`'s frequency is a SID register value rather than hertz, which both games depend on. It says so now, with the conversion from `src/audio_tables.c:84`. `TODO.md` gains the thirteen defects the two games turned up -- §6 items 30 to 33 and all of §9 -- each with a reduction that fits on a screen, the file and line of the cause, and what a fix would touch. Verified: `docs_examples` passes in both build configurations, `docs_screenshots --check` re-renders all thirteen figures and byte-compares them, the full 109-test suite passes in both builds, every quoted fragment was checked to appear verbatim in the listing it came from, and every relative link and anchor resolves. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 22:54:42 -04:00