922511c8a75a329c3b76aabaf138f3c52c202bdf
22
Commits
| Author | SHA1 | Message | Date | |
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 Anachronaut
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922511c8a7 |
A retro thruster, at half the strength of the one that lifts
Arresting a rise meant a sideways burn and a wait for the orbit to come back round. That is how a rendezvous really is flown and it is a lot to ask of somebody who has not flown one before, so down now makes the correction directly. HALF THE STRENGTH, deliberately: one sixteenth a tick against two, which is exactly gravity's own step. So it can stop a climb and it can hurry a descent, and it can never turn a landing approach into a crash faster than simply letting go would - the cheap way out of a mistake stays the expensive one. Four against eight on a keyboard, which is the same ratio. It does NOTHING to a lander on the ground, and that guard is load bearing rather than tidy. touchdown has already had its say and returns early once a lander is down, so there is nothing underneath to stop it and no crash to say it happened: measured without the guard, holding it drives the lander clean off the picture and spends a fifth of the tank doing it. ---- And the fixture that hid all of that ---- The first version of the landed check passed just as happily with the guard deleted, and the reason is worth writing down. A lander that has landed WAITS to be told its message has been read, and the keyboard fixture pads with NULs, which are not keys. So the program sat in that loop for ever and the picture was frozen at the moment of touchdown - every thruster held afterwards did nothing, which reads exactly like a working guard. The pad now presses A to get past the wait before the check tests anything, and both the row AND the fuel are read, because an engine that fired and moved nothing would keep the row and one that moved the lander for free would keep the fuel. The altitude bar check upstream leans on that same freeze for its stable end, and its comment said "stays landed" when what it means is "is not running any more". Corrected, because that is the sort of comment that sends the next person looking in the wrong place. |
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Anachronaut
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800f555ffb |
A station in orbit, going round and not yet dockable
S1 of the station: it exists, it orbits, it wraps, it is drawn. Docking is deliberately not here - the point of stopping at this rung is to fly up and find out whether matching a four pixel a frame target feels good before any rules are written about what happens when you reach it. IT NEEDS NO PHYSICS OF ITS OWN. A body at 64 sixteenths is exactly what a circular orbit is under the rules already here: the pull and the swing cancel at that speed at ANY height, because gravity never falls off and the moon is a cylinder that does not rotate. So the station is a position, a constant, and the same fourteen bit wrap the lander uses. That also means there is no prograde or retrograde to choose - nothing privileges a direction, which is what makes a second station going the other way a thing that can exist later. Four rows above the world's origin: off the top of a forty column screen and comfortably inside a wide one, so it is somewhere to go that the zoom is needed to see. It starts half a moon away and a lap is 256 frames, a little over four seconds, so it has to be found but will not stay lost. Its column is the middle of the screen plus how far round it is from the lander, wrapped to fourteen bits - which measures the long way round whenever it is behind, so anything past the half way point becomes a negative offset instead. Off the edge needs no test at all: a sprite's X is signed and sixteen bits, so a station three hundred pixels to the left is asked for at minus a hundred and forty and the device declines. Blue, and that is not taste. White is counted to find the ceiling warning, cyan to find the landing pads, magenta is the instruments and yellow is the lander. Blue is the one ink no check measures, and picking a measured one has broken a test twice already. toPixelsSigned is factored out of showLander, since the station wants the same sign-extended conversion. Four checks, each seen to fail on its own break. Measured going round at 244 pixels in sixty frames, off the far side of the moon, and back on the other edge. |
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Anachronaut
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32559ce872 |
The room a zoom buys goes to the sky, not to the moon
Zooming out drew fifty rows DOWN from the world's origin, which put exactly the same sky on the screen as before with twice as much moon under it. Measured: 47 per cent rock zoomed in and 71 per cent zoomed out. A zoom that shows you more of the thing you cannot fly through is not worth a button. The eighty column screen is fifty rows and the flyable band is thirty - the ceiling is eight rows above the origin and the deepest valley is twenty two below it - so the twenty rows a zoom buys have to go somewhere. They go above. The wide view starts twenty four rows over the origin, the ground sits near the bottom, and the whole band is on the screen: 23 per cent rock instead of 71. Which needed three things. The moon is drawn from row minus twenty four rather than from nought, because rows above the origin are sky by definition and because whatever the shell left in them is otherwise still there. The row origin comes out of the view block like every other screen number. And the lander's own Y moves with the view, which meant making toPixels' answer SIGNED at last: it masks to twelve bits, so a lander above the origin came back as a large positive number rather than a small negative one - harmless while such a lander was off the picture either way, and wrong the moment the view moved up to include it. That is the point of the button. A lander at the ceiling is off the top of a forty column screen, which is where the orbit lives and why the altitude bar had to exist; zoomed out it is at row 149 and you can watch the whole orbit. Four checks, and the proportion is deliberately not on its own: measured alone it passes for a moon floating over a void, because pointing the view back at the origin leaves the rows under the terrain simply never drawn, and black counts as sky. Both breaks that matter went straight through it. What catches them is that the ground has to reach the bottom of the screen and the sky has to be empty - the latter only on a shell scrolled a hundred and eighteen lines deep, since that is what it takes to get anything into the rows the wide view moves into. The tap fixture also moved to frame 100. Fifty rows of moon take longer to draw than twenty five, and a six frame tap at frame thirty now lands before the program is reading a controller at all, which reads exactly like a button that has stopped working. |
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Anachronaut
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437ddf8ebe |
z zooms too, so a keyboard is not shut out of it
B was the only way to swap the view, and the game is meant to be flyable without a controller - the arrows fly it when there is no pad. Somebody without one had no way to zoom at all. Tested ABOVE the pad test rather than beside the arrows, and that is the distinction: which way the lander is flown is a question a controller answers better, so the arrows stand aside for one. How much of the moon is on the screen is not that kind of question, and a player with a pad may still have a keyboard in front of them. No edge to remember here either. The console delivers a key ONCE, which is the whole difference between a key and a held button. The check puts the z forty bytes into the keyboard file, because the console hands over one key a frame: a z two hundred bytes in is a z two hundred frames away, which is past the end of the capture and reads exactly like a key that does nothing. It cost a wrong answer first time. |
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Anachronaut
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a02d701efe |
Two zoom levels on a button, which the device already had
Forty columns and eighty are the same map, the same 8x8 cells and the same engine; only how many of them fit differs. The map is 128 by 128 either way and the moon is exactly 128 columns of it. And the front end scales whatever it is handed by the largest whole number that fits, so 320 by 200 at four times and 640 by 400 at twice fill the same glass. So the two modes ARE two zoom levels and nothing in the video device had to change to get them: forty columns shows under a third of the moon at twice the size, eighty shows nearly two thirds. Out for the orbit, in for the landing, and B says which. What did have to change is every screen coordinate in Lander, because the middle of the screen is 160 on one and 320 on the other. They now live in one block that setView copies over from whichever of two tables matches the mode, so a gauge reads a variable and never has to know which screen it is on. Several coordinates became sixteen bit on the way, since 620 will not go in a byte. follow already read HalfScreen and showLander already writes the world position straight through, so the lander itself needed nothing but its resting column. The moon is redrawn on a swap because it is filled as many rows deep as the mode shows, and a moon drawn 25 deep on a screen showing 50 floats over nothing. The swap is edge triggered. A pad is LEVEL and not an event, so a view that swapped while B was down would swap sixty times a second - which is not a zoom, it is a strobe, and it redraws the whole moon each time. The check for that holds the button for three hundred frames and requires the lander to land where a six frame tap left it; with the edge dropped it ends seventeen pixels adrift, which is the strobe costing it frames. Four checks, each seen to fail on its own break. The README's Lander entry also still described the relief orbit that the previous commit replaced, and now describes the one that is there. |
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Anachronaut
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85029d3b85 |
An altitude bar, and orbital speed marked on the drift bar
The orbit takes the lander off the top of the screen, and the panel only worked while the ground was in sight. Both other bars are rates: they say how fast, and neither says where. The altitude bar is height above the surface underneath, up the left edge, half a pixel of bar to a pixel of sky - the flyable band is about 256 pixels and the screen is 200 tall, so pixel for pixel would run off the top of the very screen it describes. Above the surface rather than above some fixed line, so it reads NOUGHT the moment the lander is down. The marks say where 64 sixteenths is. Without one that number is folklore: a pilot can feel that somewhere around here the falling stops and has no way to see where. The bar is a pixel a sixteenth from the middle at 160, so the marks sit at 224 and at the two pixels before 96, adjacent rather than overlapping - a bar at orbital speed would otherwise hide the thing it is being measured against. Both in magenta. Red and green are taken and they MEAN something here, how fast and whether it can be landed with, and an altitude is neither. White was the first choice and the ceiling check counts white to find its warning, so it read a warning that was never up - the suite caught that. Cyan was the second and it is the colour of a landing pad, which is checked as whole cells of it. groundLevel is factored out of restOnSurface, which had the same sum. Three checks, each seen to fail on its own break. Two flights, because no one flight holds both ends of the bar well: the climb reads 219 pixels and the descent lands and then stays landed. They fly on their own keyboard file - the shared one holds a key down every forty eight bytes for the held-thruster check, so borrowing it flew the lander from the keyboard and the controller at once and turned the gentle descent into a crash. |
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Anachronaut
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c514d5328e |
An orbit that comes back round, out of gravity minus the swing
The relief version could never make one. It only ever SUBTRACTED from gravity, so a lander a little too slow sank for ever and one a little too fast rose for ever - nothing in it could turn a fall around, because nothing in it ever pushed up. There was no periapse to have. Gravity minus the swing outwards has a sign change in it, and that is the whole mechanic. Below orbital speed the pull wins and the lander falls; above it the swing wins and the lander climbs; at 64 sixteenths they cancel and it circles. Falling buys sideways speed and climbing spends it, so a fall carries the lander past orbital and turns into a climb, and the climb pays it back and turns into a fall. The trade is the quarter square multiply, because the rate has to be the PRODUCT of the two speeds. Set by the vertical speed alone it drained a climb to nothing, and any minimum to stop that became a trap the climb spent its way into - measured freezing at 23 with a gate of 24 and at 3 with a gate of 4. With the product in it there is no gate: as the sideways speed goes to nothing the trade stops by itself. Half the product rather than a quarter or the high half. The high half alone is nought below a product of 256, which is a dead patch exactly where the turn begins, and a quarter still ran the lander into the roof before it came round - the whole sky is about 145 pixels. Measured, placed at 80 sideways and left alone: apoapse at -1024 with 59 sideways, periapse at -124 with 71, and round again at 165, 241, 299 and 369 ticks with no sign of decay. A period of about 22 seconds. The ceiling also spends one sideways when it wipes a climb. Without that it was a trap with no way out: the pin wipes the climb, so the trade sees neither fall nor climb and never touches the speed that is pushing the lander up. Measured pinned at the top with 117 sideways, unmoving, for the whole of a four minute flight. Tests/makedisks.sh needed the library path, since Lander now includes math.asm, and the app went from 2,924 bytes to 4,651 - mostly the 1,022 byte table - which is what the listing expectations move for. |
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 AnachronautandClaude Opus 5
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f5642f52b5 |
A ceiling that pins rather than ends
Climbing made a sixteen bit height count down past nought and round to 65535, so a lander that kept going came back through the bottom and hit the ground FROM ABOVE. Two thousand pixels of climb, which a full tank reaches easily. Pinned instead, and told so in the window. Leaving upward is RECOVERABLE - gravity is always there and a lander with fuel can always come back - so ending the run would punish a state the player can fly out of. What kills you out here is running dry a long way from the ground, which is a death somebody flew into rather than one a boundary handed them. TWO DIFFERENT LINES, and both were got wrong before they were got right. The warning covers being AT the ceiling or above it: compared against the ceiling itself, a pinned lander read as back inside the world the next frame and the warning was written and wiped sixty times a second, so it never appeared at all. The pin covers being STRICTLY above it: including the ceiling dragged the height back every frame and the lander could never descend, which is a lid nobody can leave and worse than the wrap. And only the climb is spent, never the fall. Zeroing the speed outright pinned it there for ever - gravity adds once a tick and a clamp running every frame wiped the pull nine times out of ten. The orbit check is gone, and the reason is in video.sh. Every window where the difference showed turned out to be a few frames wide: hold the thruster and both landers are pinned with their climbs spent, ease off and both land and freeze. A version of it passed against one disk and failed against another, which is a check measuring the boot time rather than the physics. Orbit is verified by measurement and said to be so, rather than left looking tested. cosmosLanderDry wants seventy million cycles now instead of forty: it spends the whole tank at the ceiling before it falls the length of the world. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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a069ee7a00 |
Orbit, and two bars that answer instead of reporting
Going sideways lifts the moon off you. Not because gravity weakened - because at speed the surface falls away underneath as fast as the lander falls towards it, which is what an orbit is. A GRADIENT OUT OF INTEGER ARITHMETIC. Gravity is one sixteenth of a pixel a tick and there is nothing between that and nothing, so it cannot be scaled down. Instead four times the sideways speed goes into a byte every tick and the tick's gravity is skipped whenever that byte carries: the fraction cancelled is the speed over 64, smoothly, with no multiply and no divide. At four pixels a frame it carries every time. That is the linear approximation; the honest one is the square, and wants a table. It did nothing at all for its first two versions. Once because the relief was a 256th a tick, so orbit wanted a speed no lander would reach; and once because A IS THE HIGH HALF of the shift register, so multiplying by four left the answer in A while the code read B, which is nought. The same trap as the scroll register and the pixel conversion before it. And a bar for the vertical speed beside the one for drift, both GREEN WHILE A LANDING WOULD SURVIVE AND RED WHILE IT WOULD NOT. That turns two numbers into one question - can I put down - and answers it at a glance. WHAT THIS COST: the flown delivery check. A recording is a list of buttons and not a flight, so replaying it under different gravity flies somewhere else; the delivery became a crash two columns short. The fixture is still there and is still a faithful record of what somebody did, and is no longer a record of what happens. That is the standing cost of a flown fixture, and it is worse than the transcript tests dropped earlier: those broke when an output moved, and this breaks whenever a NUMBER moves. Making the delivery reachable without flying - a way to start already carrying, or at a chosen base - is what would fix it properly. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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caf5e1f99d |
A base speaks in the window, not into the world
Two bugs with one cause. The console draws into the map, so a message printed while flying was a message the lander then flew over - and printing scrolls, so every one of them moved the whole world up a row. The window is at a screen position and forty cells wide, and neither is true of it. So the window is two rows now: the gauge, and whatever there is to say. The letters are ordinary tiles, because the character generator starts at the space and glyph n is character n less thirty two. The rest of the row is blanked after every message, or a short one would leave the tail of a long one behind it. Opening the throttle wipes the line, because a message that outlived the moment would be read as describing this one. The crash still goes to the console, deliberately: it is the last thing the program says and it should survive the program. A or Start continues from a message as readily as a key does. Somebody flying on a controller should not have to reach for the keyboard to say they have read something. AND TWO TESTS WENT WITH IT, which is the interesting part. cosmosLanderSoft and cosmosLanderPadOne asserted on lines in a transcript, and the lines moved off the console - so both went on passing while checking nothing at all. A test that asserts a side effect rather than the thing itself is always one refactor from being decorative. What they were for is now checked in the picture, where the message actually is. The lander check moved earlier too. The window grew to two rows, so by 1.5 million cycles the lander had climbed behind the status bar - the window doing exactly what it should, and leaving the check counting six pixels of a forty pixel lander. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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bfb515e23b |
Cargo: bases with names, and a landing that is not an ending
Four bases, told apart by the scheme their pad is drawn in, so "the cyan one" is a thing a person can say and a thing the machine already knows. Yellow is missing on purpose: it is the lander, and a base the same colour as the thing landing on it would be a poor joke. Land empty at a base and it loads cargo for the base ACROSS THE MOON, two along - so the pairs are cyan with red and green with blue, and the wrapping surface is a route rather than scenery. Land carrying at the right one and it takes the cargo and pays eighty units of fuel. Land at the wrong one and nothing happens, which is why the destination will want to be on the screen. A LANDING NO LONGER ENDS THE RUN. The lander rests where it is, exactly on the surface with both speeds zeroed, until the throttle opens again - which is the only way to stop being landed. Gravity does not pull on something already sitting down, and a base does not hand out cargo sixty times a second to a lander parked on it. The pad array holds the base's number plus one rather than a flag. Nought still means no pad, so it is still one lookup, and a flag would have to be followed by "and which of the four" - the same walk done twice for an answer already in hand. Pads are eight columns rather than four. Four was 32 pixels in a moon 1024 round, which is a target somebody flying by feel misses over and over. WHAT IS NOT COVERED, and why: the delivery and wrong-base paths need a lander flown from one base to another, and hand-authoring a recorded pad input that hits an eight column pad across a 128 column moon is a piloting exercise rather than a correctness one. Several attempts got within two columns. Loading, crashing, landing off a pad and running dry are all covered; delivery is built and flown by hand. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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7257ad369c |
Landing pads, carved rather than looked for
A random walk does not leave flat ground and a lander wants some. Four pads are cut into the moon after it is generated, each four columns levelled to whatever height its first column happened to have - so they sit in the landscape rather than on a shelf above it. The moon decides where they are; this only decides that they are flat. Searching for flat spots was the alternative and it can fail, which means a fallback that carves anyway - the carving, plus a search nobody needed. They are marked by an ATTRIBUTE and not a tile of their own, which costs no art at all: a nibble is added to every index in a tile, so one solid block is grey moon or a cyan pad depending on the byte beside it. Which columns are pads is an array, because asking has to be one lookup. Four comparisons per column per row is 12,800 of them for one screen, and the landing verdict asks the same question again. THE LANDER STARTS ABOVE ONE, because that is where a porter's day begins. Starting in the middle of nowhere meant a straight descent landed in the middle of nowhere, which is a fine thing to be able to do and a poor thing to have to. That change cost the crash test its teeth, and the way it did is worth keeping. It held nothing at all and let the lander fall - and a short drop onto the high ground of the base you started above is survivable, which is correct, and left the test saying nothing. It holds Right now: lateral speed has no limit and nothing slows it, so a slide always ends badly however the rest is tuned. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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2274be4b68 |
Lunar Porter, rung three and a half: fuel
Every thruster costs a unit every tick it fires, so holding two at once costs two - the honest price, and it makes a drift you corrected expensive in a way a drift you avoided is not. AN EMPTY TANK IS NOT AN ENDING. There is no message and nothing stops: a lander with no fuel is still flying, it just cannot do anything about where. What happens next is gravity, and gravity is patient. The test for it holds the thruster from the first frame to the last and crashes anyway, which is what says the fuel is real - a lander that could hold Up for ever would land every time, and the economy this is the first half of would have nothing to buy. The gauge is in the window, which is what the window was built for two commits ago: a bar at a SCREEN position, so the moon turning underneath does not carry it off. Thirty five cells after a label, redrawn whole every frame because seventy bytes out of one port is cheaper than working out which of them changed. A byte of fuel, and a byte is enough. Over eight it is a bar of up to thirty one cells - a shift, because there is no divide - and at a unit a thruster a tick it is about forty seconds of holding the engine open. Sixteen bits would be more arithmetic for a number nobody reads to the unit. Cargo and the bases are the other half. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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e3eccd17a8 |
Settle the view before saying how the landing went
The console draws into the map and the map is what is being scrolled, so a message printed while the view was three pixels into a cell came out three pixels off the top, with as much of its first row missing as the cell above it had lost. The flying is over by then, so the fractional part of the view has no more work to do. Putting it back is what makes the whole message visible. This is not the general problem. A status bar that has to stay readable WHILE the map moves is a different thing entirely, and nothing here solves it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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a074a831f0 |
The shell scrolls, and the moon was drawn where nobody was looking
Lunar Porter never put the row origin back. The map is a ring 128 rows tall that the screen shows 25 of, and the shell leaves that origin wherever its last command finished - so a moon drawn into rows nought to 24 while the screen is reading from row forty is a moon nobody can see. It came out as terrain missing, or half there, depending on how far down the prompt had got. Running Pad first was enough; so was holding Return. Nothing here is tidiness. It is the difference between the rows a program WRITES and the rows the screen READS, and only one of those is under the program's control. Grid has always known this; Lander did not. The check for it needed writing twice. Forty returns caught nothing, because the shell runs an eighty column screen which is FIFTY rows tall - forty returns fill it and never scroll it, so the origin was still nought and the test passed against a build with the fix taken out. The screenful that matters is the one the shell is using, not the one the program is about to ask for. At eighty it is 28,608 pixels of moon with the fix and none at all without it. break.sh is what said so. The first version of this check looked exactly like a passing test. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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f7be843ed9 |
Lunar Porter takes any controller, not the first one
A controller does not always arrive on pad nought. The front end hands out the numbers the host gave it, so a game that reads only the first one works on the machine it was written on and silently does nothing on the next - which is the shape of "the pad is detected, Pad shows it, and the game ignores it". Four reads and three ORs. One person flies this and which socket they plugged into is not a thing they should have to know. Presence is any of the four bits rather than the low one, for the same reason. The manifest's pad column takes several fixtures now, comma separated, and they fill the pads in turn. So cosmosLanderPadOne holds nothing on pad nought and flies the whole landing on pad one - a test that fails on the version of this program that shipped an hour ago. Also confirmed while looking: raylib 6 does refresh which gamepads are ready every frame in PollInputEvents, so a hot-plugged pad should be seen. Whatever is stopping that is above us and worth a separate look. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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df50c2f0f8 |
The pad was working; the game was told there was not one
0x64 counted only the RECORDED pads. So a controller plugged into Voyager reported its buttons perfectly, and every game asking whether there was a controller was told no - which is exactly what Lunar Porter asked, once, at startup, before falling back to the console for the rest of the run. The cause is worth naming: a front end calls padSet every frame for every pad, so "held nothing" is the commonest thing it says and cannot also mean "there is no pad here". Connected is said separately now. Pad nought is always there behind a window, because the keyboard is behind it - which is the useful answer rather than the literal one. And Pad.asm, which is what should have existed before any of that guessing began. It prints a line whenever a pad changes, and tells apart the three states that look identical from inside a game that will not respond: one nobody noticed, one mapped to nothing, and a mapping that is wrong. WHY A PROGRAM AND NOT A PRINT IN THE FRONT END: because the question is what the MACHINE can see. A front end reporting what it thinks it is sending answers a different question, and the gap between those two is the whole of this bug. It also found that osPrintNumber takes A as the HIGH half - the same way round as the shift register and every other pair here, and not what a byte in A wants. Every value came out 256 times too big. Gravity is one frame in ten rather than six. The ratio between thrust and gravity is the feel; how often the tick comes round is how fast that feel arrives, and one in six was still touchy. Same lander, more time to think. And the verdict waits for a key. It printed and left immediately, taking the screen with it - so the one thing worth seeing, the lander sitting on the ground it had just reached, was gone before it could be looked at. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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8eb4e4d67e |
Lunar Porter, rung two: it lands, or it does not
The terrain is an array in Data Memory rather than something read back out of the map, and that is the whole reason this is cheap: the ground under the lander is one index into 128 bytes, where asking the screen would be a transfer through the controller every frame. The column is the world position over eight, masked to the moon's 128. The surface is that column's row times eight - three turns left of the shift register, since a row is at most 24 and 192 fits in the low half. The feet are the lander's top plus its eight pixels. WHAT DECIDES IS THE SPEED AT THE MOMENT IT ARRIVES. Both of them, and both have to be gentle: three quarters of a pixel a frame downwards and half of one sideways. Sideways is the tighter on purpose, because a landing that was soft downwards and sliding is a lander on its side - which is the interesting half of the difficulty, and the half the drift bar was blind about until it existed. Two fixtures say it works, and they differ only in what was held: one holds nothing and falls the whole way, the other pulses the thruster six frames in sixteen and survives. Same terrain, same seed, same keys. Also: the gamepad did nothing, and the reason is that the four direction buttons are the D-PAD. A lot of controllers made this century have one nobody uses - the thumb goes on the stick, which reports as an axis rather than a button - so a pad that was plugged in and working correctly did nothing at all. The stick counts as held past halfway now. Untested here, because there is no controller in this environment and the suite runs headless; Voyager also says at startup which controllers it can see, so a pad that still does nothing can be told apart from one nothing noticed. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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db0c26e13f |
A bar for the drift, and a lighter touch sideways
A moon has no air, so a sideways drift never stops by itself and stopping one means cancelling the velocity EXACTLY. That is not hard to do; it is hard to do blind, which is what it was - a number nothing on the screen said anything about. So sprite one is a bar whose width is the drift. It runs right from the middle of the screen for a rightward one and left for a leftward one, so which way is as plain as how fast, and stopped is the one state with nothing drawn at all. The whole of it is a target width written once a frame; the device stretches one tile into it and the program draws nothing. Sideways thrust is one a tick rather than two. At two, the smallest correction available was twice the size it needed to be and overshooting was the normal outcome. WHICH ZERO MEANS NOTHING TURNED OUT TO MATTER. A target width of nought is the NATURAL width, not an empty sprite - so a bar with no drift in it came out eight pixels wide, sitting at the middle of the screen, saying "stopped" in the same shape it says "drifting slightly". What draws nothing is a SIZE of nought, which is the other zero in the other byte. Both meanings are deliberate and documented and it still caught me out inside a week of writing them down. The check for it earned its place by failing on that before it was found, which is the best evidence a check can offer. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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b1dde7908c |
Lunar Porter flies on a controller
A held thruster burns every tick it is held for, which is the whole reason the pad exists: the console can only say a key went down, so a thruster driven by it could be pumped and never leaned on. The burn happens on the same tick gravity does, and for the same reason - a sixteenth of a pixel is the smallest step this arithmetic takes, and applied sixty times a second it is an enormous acceleration. On the tick, thrust and gravity are two numbers whose RATIO is the whole feel of the thing. Position still moves every frame; only the acceleration is stepped, and nothing can see that. Two against gravity's one, so climbing and falling are the same speed. Three was the first try and it left the moon after about a second of holding. If there is a pad the console's arrows are ignored, because under a window the same keypress reaches both - the pad as a level, the console as a byte - and a thruster that fired twice for one press would be a mystery to anybody tuning it. q still quits, since a pad has no letter for it. With no pad the arrows still burn once a press, which is the most that can be done down a wire. And break.sh now rebuilds the disk images as well as the binaries. Half the things worth breaking here are SplitBit assembly rather than C, and those live on the fixture disks - so an edit to a .asm file changed nothing the suite could see, and the tool reported that nothing caught the break. That is the exact lie it was written to prevent, turning up in a new place. With the disks rebuilt it catches this one: the lander falls between the two captures instead of climbing. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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88ecb208f4 |
The coarse scroll register was being sent the wrong register
CALL eighth OUTA 0x36 RET puts A back the way it found it, so the column origin was written the high byte of the position that had been passed in, and the answer the subroutine had worked out went nowhere. The fine register was computed inline with OUTQ and was correct, which is exactly what it looked like from the outside: smooth scrolling within a cell that never advanced one. Q is the only register that crosses a RET. Every other answer in this program already came back in it; this one had been written as if A would do, and A very nearly does, which is what makes it worth a comment rather than a fix. Gravity was Jupiter's. A sixteenth of a pixel per frame per frame is the smallest step this arithmetic can take and it crossed the screen in a second, so it is applied one frame in six instead - which divides the pull by six and costs a byte and a compare. The alternative was a finer unit for velocity than for position, and that means a shift every time one is added to the other, twice a frame, for ever. And the check that catches all this now looks 1.5 million cycles in rather than twelve. The first number came from assuming a program that saves a whole screen takes a long time to start; it does not, and by twelve million the lander had flown seven hundred frames and left the picture. A capture near the beginning is worth more than a tuned one - there is less between it and the start that can move. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |
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AnachronautandClaude Opus 5
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d6c81fa32c |
Lunar Porter, rung one: it flies
A lander over a moon that wraps. Landing, crashing, fuel, cargo and bases are not here - this rung exists to answer whether it FEELS right, because everything after it is bookkeeping and none of it is worth building on a lander that is no fun to fly. The moon comes for free. The map's column origin is a ring in hardware, so 128 cells is 1024 pixels of surface with no edge and no seam to cross. Position and velocity are sixteen bit in SIXTEENTHS OF A PIXEL, and the unit is the design: gravity is a small number added to a velocity and a velocity is a number added to a position, with no multiply or divide anywhere. 1024 pixels is 16,384 sixteenths, which is 2^14 - so going all the way round is an AND with 0x3FFF rather than a comparison, and it is never wrong at the seam. The lander never moves sideways. The world scrolls under it and it sits at the middle of the screen, which is a byte a frame instead of two and is also what makes the wrap invisible: there is no moment where it jumps. One key is one burn. The console says which key went down and there is no such thing as a key coming up, so a thruster cannot be held - a press adds to the velocity once. That is a property of the machine rather than a choice this program made, and it reads as pumping the engine. Four bugs found by running it, all worth keeping written down: B CANNOT BE A LOOP COUNTER here. Every comparison is an INIB, so the count was overwritten by whichever bound was last tested and the loop reset itself for ever. Counters that outlive arithmetic live in memory. A subroutine answers in Q, and the AND after it read A. The moon came out flat because it was testing the height against 1 instead of the random number. Row minus height, not height minus row: they are equal at the surface, equal does not borrow, and the surface row has to be ground. And the shift register has A as its HIGH half. Written the other way, the view scrolled by 256 cells for every one it should have. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW |