2 Paint the Maze
By the end of this chapter, the land answers your hands. Choose a terrain with its button, its picture or a number key, and paint the map with a click or with Enter. The arrow keys walk the orange ring, and D brings the supplied map back.
The game as it is at the end of this chapter. Click the game to play.
If your game and this chapter part ways, here is the chapter’s finished project. Open it and compare, or start Chapter 3 from it.
To open it, start Myth Engine, choose File › Open Project... and pick the downloaded file.
Starting with this chapter? It begins where Chapter 1 ends, and Chapter 1’s Goal has that chapter’s finished project.
2.1 The Idea
In Chapter 1 the map lay on the table, and nothing answered. You could click a cell all day. This chapter hands you the brush.
Choose Forest and click the road beside the camp, and pines grow there. Of the four terrain buttons, the tan one is the terrain you’re painting with, the brush. The orange ring marks the selected cell, the one the keyboard paints, and the arrow keys walk it from cell to cell.
Here’s a question worth asking before you build anything. What does painting change? It looks like the cell’s picture, but it isn’t. In Chapter 1, every cell showed the picture its cost called for, and the costs lived in Maze Cells. So painting changes a cost in Maze Cells, and the picture follows. The cell you click never draws anything by itself.
That matters for what’s coming. Each cost you paint is a price. You pay a cell’s cost when you step onto it, and the camp, where you start, costs nothing. In Chapter 3, Dijkstra’s algorithm reads these costs, and nothing else.
The keys are new too. The game never asks whether the Enter key went down. It asks whether Paint was pressed. Paint is a Command, a name for something the player means, and the keys are whatever the player presses for it.
One quiet piece turns up here too: a Function that answers which cell lies next door. The arrow keys need it now, and the search asks it again in Chapter 3.
2.2 The Plan
Here’s how the pieces work together. Read each line from left to right. Most of the names are new again, so skim them now. Come back at the end of the chapter, when every name is a piece you’ve built.
- A terrain button or its picture is clicked, or 1 to 4 is pressed -> Choose Brush makes that terrain
$brush-> every Terrain Button colors itself again. - An arrow key is pressed -> Move Selection asks Select Neighbor, which asks Find Grid Neighbor for the next cell ->
$selectedCellchanges -> Show Selection moves the ring. - A cell is clicked -> Paint Map Cell makes it
$selectedCelland sendspaintRequested-> Change Terrain calls Paint Selected Cell. - Enter is pressed -> Change Terrain calls Paint Selected Cell too.
- Paint Selected Cell writes the brush’s cost into Maze Cells and sends
terrainChanged-> every Map Cell shows its picture again. - D is pressed -> Restore Defaults puts Maze Cells back, puts the ring on the camp, and sends
terrainChanged.
2.3 Set Up
This chapter’s Set up card has no ART block and no GAME SETTINGS block. It brings the game’s controls, one new Global Variable, and a block about what changes.
COMMANDS are the controls, seven of them. Make them all now, in Game Settings, under Input Manager. The Set up card on the Making page shows how each one is made and given its key. Six are Buttons, with one key each. Move Selection is a 2D Axis, with a row for each arrow.
The Input Manager opens on your project’s one Input Context, Default. An Input Context is a set of Commands that the game can switch on and off together. Weighted Maze needs only this one. It’s chosen already, so every Command you add goes into it.
GLOBAL VARIABLES has one new row, $selectedCell, the number of the cell the ring stands on. Add it on Reset Trial’s Globals card, with + and New Global…, as in Chapter 1. A new Global is already a Number at 0. It needs only its name.
Two Actions in this chapter, Set Data Cell and Reset Data Table, stay out of the Action List until Advanced Mode is on. Turn it on now, with Settings > Advanced Mode.
The card’s last block, REMOVED, needs a warning before you reach it. This time, don’t delete what it lists. Show Map Cell, Show Terrain Choice and Show Terrain Picture lose their names, but their work stays. Each takes on a new job in this chapter, and a new name to match, and the part that needs it renames it. Show Terrain Choice Data is renamed too.
A renamed Logic Component stays on its Object, and keeps every value its placements gave it. So the eight terrain placements still hold their terrains, under Per Instance Variables. There’s nothing in the Scene to change.
1234Left ArrowRight ArrowUp ArrowDown ArrowEnterD2.4 The Brush
First, the sidebar answers.
Click Forest. Its button turns tan, and Road’s goes pale. Click the picture of mud beside the third button, and Mud turns tan instead. The map doesn’t change at all. Choosing a brush never does.
The brush is $brush, the Global Variable that has said Road since Chapter 1. Three things will set it: the buttons, the pictures beside them, and, in the next part, the number keys. All three call one Function to do it.
2.4.1 Choose Brush
Choose Brush makes one terrain the brush, but only a real one. It’s handed a name, terrain, and before anything else it looks for that name’s row in Terrains, the check Show Terrain Choice makes.
Only then does it set $brush. So a name that isn’t a terrain can never become the brush, and painting always finds a cost. Its Description, like several in this chapter, says the learner where this book says the player. A Function card on the Making page shows how to make it.
Makes one terrain the brush, the terrain the learner paints with. terrain must be a row of Terrains (Road, Forest, Mud or Wall); a name Terrains does not list leaves the brush as it is.
- Action Name
isKnownTerrain- Table
"Terrains"- Row
terrain
isKnownTerrain.value == true- Variable
$brush- Value
terrain
2.4.2 Highlight Terrain Choice
This Function colors one Terrain Button: tan, its chosenTint, while the button’s terrain is the brush, and pale, its plainTint, the rest of the time.
You’ve built this before. It’s the If and Else from the end of Show Terrain Choice, moved into a Function so two Events can share it.
One thing is new. The button comes in as a Parameter, button, because a Function has no Object of its own. It’s an Object, Structural, with one Required Component: the Sprite. Both settings are under its row’s Settings arrow, as A Function card on the Making page shows. The two Change Sprite Tint Property Actions name the Object they color. On each block, Applies To is the box after the word on, and it starts at Self. Pick button.
Colors one Terrain Button: chosenTint while its terrain is the brush, plainTint otherwise.
spriteSpriteterrain == $brush- Applies To
button- Value
chosenTint
- Applies To
button- Value
plainTint
2.4.3 Choose Terrain
Show Terrain Choice learns to choose, so it gets a new name. Right-click it in the Resources, choose Rename, and type Choose Terrain. It stays on the Terrain Button. Every placement keeps its terrain, under Per Instance Variables.
Its Data Structure follows. Rename Show Terrain Choice Data to Choose Terrain Data the same way. The Data Structures card shows the new name at once. But the Logic still reads it as self.showTerrainChoiceData, the name Myth gave it in Chapter 1. The card says self.chooseTerrainData, the name a new one would get. Both reach the same label field, so leave your boxes as they are.
Open Choose Terrain. The pointed block beside When Created is its Mode, and it still says Show Terrain Choice. The game never reads that name. It’s there for you, so give it the new one: right-click it, choose Rename Mode…, and type Choose Terrain.
The card below shows Choose Terrain as it ends up, with no marks. A new name makes a new card. So here is what changes from your Show Terrain Choice. The Components card gets a second line, self.sprite, because Choose Terrain hands itself to Highlight Terrain Choice as the button. If it doesn’t turn up by itself, press the card’s + and pick Sprite.
Your steps 7 to 10, the If with its Else, go. Right-click that If and choose Delete. Delete takes only the If. What it held stays behind, standing apart: the Else and two Change Sprite Tint Property blocks. Delete each of them the same way.
In their place comes the card’s step 7, a call to Highlight Terrain Choice. It sits at the end of step 2’s line, so right-click step 2’s If and choose Add inside Then. Pick the Function in the window, and join it with Connect to sequence. Its button box already says self. Type the other three as the card has them.
Two Events are new. A click on the button runs UI Activated, and its terrain becomes the brush. And whenever $brush changes, Variable Changed runs on every Terrain Button, and each one colors itself again.
So the click colors nothing by itself. It changes $brush, and every Terrain Button follows the change on its own.
Each Event has a line of its own, from its Mode down to End. Press Add Event and pick UI Activated. Its big block joins the canvas, with a Mode beside it and End below. Nothing is between them yet. Its Mode may say Mode 1. Leave it, or rename it as you did the first.
An Action you add now lands beside that newest Event. So add Choose Brush right away, and Connect to sequence joins it to UI Activated’s line. Then add Variable Changed the same way, with brush picked in its second window, and its call after it.
The card heads the two Events with the names Myth gives them: On Hud Activated, and On Variable Changed · Brush. You never type either one. From Chapter 3, you’ll pick Events from a list by names like these.
One terrain the learner can paint with. The button shows the terrain's name and, unless it is a Wall, what entering it costs (from Terrains); activating it makes that terrain the brush, and the button is highlighted while it is. Each Terrain Button placement sets terrain, a row of Terrains (Road, Forest, Mud or Wall). chosenTint and plainTint are the button colors with and without the highlight.
Any Objectself.chooseTerrainDataText / UISprite- Action Name
isKnownTerrain- Table
"Terrains"- Row
self.terrain
isKnownTerrain.value == true- Component Value
self.chooseTerrainData.label- Value
self.terrain
data('Terrains', self.terrain, 'cost') >= 0- Component Value
self.chooseTerrainData.label- Value
self.terrain + " " + data('Terrains', self.terrain, 'cost')
- Component Value
self.text.text- Value
self.chooseTerrainData.label
- button
self- terrain
self.terrain- chosenTint
@self.chosenTint- plainTint
@self.plainTint
- terrain
self.terrain
- button
self- terrain
self.terrain- chosenTint
@self.chosenTint- plainTint
@self.plainTint
What one Terrain Button keeps: label, the words it shows (the terrain's name, and its cost unless it is a Wall).
The Terrain Button’s card, next, is your first Changes card, and all it shows is the renames you’ve already made. Changes cards on the Making page shows how to read one.
Window / UIUIX 216, Y 48Terrain17Bold#203F43CenterVector-1PanelX 216, Y 48#EEE3CCChoose TerrainChoose Terrain DataShow Terrain ChoiceShow Terrain Choice Data2.4.4 Choose Terrain By Picture
Show Terrain Picture gets the same treatment. Rename it Choose Terrain By Picture, and its Mode too, and leave its When Created Event as it is.
One Event is new, UI Activated again, on a line of its own. A click on the picture calls Choose Brush with its terrain, as the button does. The buttons don’t need telling, because they follow $brush.
Shows the Terrain Tiles picture of one terrain beside its button (Terrains frame); activating the picture makes that terrain the brush, as its button does. Each Terrain Preview placement sets terrain, a row of Terrains (Road, Forest, Mud or Wall).
Any Object- Action Name
isKnownTerrain- Table
"Terrains"- Row
self.terrain
isKnownTerrain.value == true- Frame
data('Terrains', self.terrain, 'frame')
- terrain
self.terrain
The Terrain Preview’s card shows that rename too, and it’s done already.
Window / UIUIX 54, Y 54-1Terrain TilesX 54, Y 54Run the game. Try a button, then a picture: the tan moves each time, and the map stays exactly as it was.
2.5 The Number Keys
Now the keyboard chooses too. Press 2, and Forest turns tan, or press 4, and Wall does. Each number is the key of one Command from the Set up: Choose Road on 1, Choose Forest on 2, Choose Mud on 3, Choose Wall on 4.
2.5.1 Choose Terrain By Key
Choose Terrain By Key has four Events, and each makes one call. Each Event is a Command Pressed, set to its Command in a second window. It runs once each time that key goes down. Holding the key doesn’t repeat it. Add the Events one at a time, and give each its call right after you add it, so the call lands by its own Event.
Every call is Choose Brush, with its terrain’s name: Road, Forest, Mud or Wall. The names go in bare, with no quote marks. These boxes take a word as it is, as Values, quote marks and all explains. Once you’ve typed one, the block draws it in quote marks, “Road”. It’s still the bare word you typed.
It never asks which key was pressed. Map Choose Road to another key in the Input Manager, and this Logic works the same.
Make it, and attach it to the Selection. The ring is the keyboard’s home in this game, and the arrow keys come to it next.
Lets the keyboard choose the brush: Choose Road, Choose Forest, Choose Mud and Choose Wall (keys 1, 2, 3 and 4 in the Input Manager) each make their terrain the brush.
Any Object- terrain
Road
- terrain
Forest
- terrain
Mud
- terrain
Wall
Run the game, and press 3. Mud turns tan. Press 1, and Road is the brush again, tan at the top of the list.
2.6 The Ring Walks
Next, the orange ring learns to move.
Press the right arrow. The ring steps off the camp onto the road beside it. Press Down, and it drops a row. Hold a key down, and it still takes one step: one press, one step. At the top of the map, Up does nothing, and the ring stays.
Behind the ring is one number. It’s $selectedCell, the cell the ring stands on, and the arrow keys change it. Show Selection moves the ring.
2.6.1 Show Selection
In Chapter 1, Show Selection put the ring on the camp. Now it keeps the ring on $selectedCell, wherever that goes.
When the ring is made, Show Selection sets $selectedCell to the camp and moves the ring there. Its new Event is Variable Changed, with selectedCell picked in its second window. It runs whenever $selectedCell changes, and moves the ring to the new cell. But it doesn’t run as the game starts. Variable Changed compares the Global with what it held a moment before, and at the very start there’s nothing before to compare with. So When Created’s change doesn’t count, and When Created moves the ring itself.
Your Set Position was step 2. On the card it’s step 3, because two new steps come in above it. A new block always joins the end of the line, so the quickest way is to start the line again. Do it before you add the new Event. Take both old steps out with Delete, and add the card’s three in order. Then add Variable Changed, and its two steps after it.
Keeps the Selection, the ring around the cell the keyboard will paint, on the selected cell (the Project Global selectedCell). The Selection starts on the Camp (Maze Settings startCell).
Any Object- Action Name
place- cell
data('Maze Settings', 'rules', 'startCell')
- Variable
$selectedCell- Value
data('Maze Settings', 'rules', 'startCell')
- Action Name
campPosition- cell
$selectedCell
- Position Relative To
Screen- X
campPosition.x- Y
campPosition.y- X
place.x- Y
place.y
- Action Name
cellPosition- cell
$selectedCell
- Position Relative To
Screen- X
cellPosition.x- Y
cellPosition.y
2.6.2 Find Grid Neighbor
Here is the chapter’s one hard idea, and it gets room.
Find Grid Neighbor answers one question: which cell is next to this one, in this direction? You hand it a cell and a direction. It hands back the neighbor.
You might think that’s one sum: to go right, add 1. But cells are numbered the way you read a page, and a page wraps. Put the ring on cell 12, at the left edge of the second row, and press Left. Take 1 off its number, and you land on the far right of the row above, clear across the map. There’s nothing to its left. That’s the edge.
So Find Grid Neighbor never steps along the numbers. First it turns the cell back into a place, a column and a row, with the same sums as Cell Screen Position. Then it takes the step from the direction’s row of Directions. Now the question is plain. Is the column 0 or more and below 12, and the row 0 or more and below 10? If so, it’s a cell. Its number is the row times 12, plus the column. If not, the step went off the map, and the answer is -1, no cell at all.
Count it through. From the camp, cell 0, press Right, and the column goes from 0 to 1. The row stays 0. Both are inside, so the neighbor is 0 times 12, plus 1: cell 1, the road beside the camp. Now press Left on cell 12. Its column is 0, so the step makes it -1, and that’s below 0. The answer is -1. The ring stays where it is.
Find Grid Neighbor reads two tables, one new and one that needs a new column. Both come before its card.
The four directions are rows of a new table, Directions. Each row says how far one step goes across, in columnStep, and down, in rowStep. Up is -1, one row less, because rows count down from the top of the map. Keep the rows in the card’s order. In Chapter 3, the search looks around each cell in that same order: up, right, down, left. Its two columns are the fields of Directions Entry, on the card after it, as in Chapter 1. A Data Table card shows how to make one.
0-11001-10One row of the "Directions" Data Table.
Maze Settings needs one more column for the map’s ten rows: rows, a Number with the Default 10. Its columns are the fields of Maze Settings Entry, so open that from the Resources and press Add Field. The new field comes last, after goalCell. The card lists it second, as the finished game has it, but the order doesn’t matter. The Logic finds a column by its name.
One row of the "Maze Settings" Data Table.
A new field fills the rows already there with 0, whatever Value you give it. So open Maze Settings and type 10 into the rules row too.
12100119Now the Function itself. Its first three steps are Declare Variables: column, row and neighbor, which last only while the Function runs. Steps 4 and 5 are Cell Screen Position’s sums. The % sign gives what’s left over after dividing, and floor() drops the fraction. So cell 12 is 12 % 12 = 0 across, and floor(12 / 12) = 1 down.
The If’s condition is four tests joined by &&, so all four must be true. That’s the whole guard against wrapping. It’s one box, typed as the card spells it, as If, Else and Repeat shows.
The answer is neighbor. It starts at -1 every time the Function is called, and Otherwise sets -1 again. Either would do alone. The Otherwise says it where the edge is found, so the If reads as the whole answer: a cell, or -1. The Return, step 13, hands it back. So the Return Type is Number.
The cell next to one cell in one direction (a row of Directions: Up, Right, Down or Left), or -1 when that side of the cell is the edge of the map. Cells count as Cell Screen Position counts them: Cell 00 is the top-left cell, and a row holds Maze Settings columns cells.
- Name
column- Value
0
- Name
row- Value
0
- Name
neighbor- Value
-1
- Variable
column- Value
cell % data('Maze Settings', 'rules', 'columns')
- Variable
row- Value
floor(cell / data('Maze Settings', 'rules', 'columns'))
- Variable
column- Operator
+=- Value
data('Directions', direction, 'columnStep')
- Variable
row- Operator
+=- Value
data('Directions', direction, 'rowStep')
column >= 0 && column < data('Maze Settings', 'rules', 'columns') && row >= 0 && row < data('Maze Settings', 'rules', 'rows')- Variable
neighbor- Value
row * data('Maze Settings', 'rules', 'columns')
- Variable
neighbor- Operator
+=- Value
column
- Variable
neighbor- Value
-1
- Value
neighbor
A player only ever sees the ring stop at the edge of the map. In Chapter 3 the search asks this Function too, about every cell it settles.
2.6.3 Select Neighbor
Move Selection, next, has four Events, one for each arrow. Each needs the same two moves: ask Find Grid Neighbor for the cell next door, then go there only if it’s on the map. Select Neighbor makes those two moves for all four. So the edge is checked in one place, and each arrow makes one call, with its direction.
Moves the selection (the Project Global selectedCell) one cell in one direction, a row of Directions. At the edge of the map the selection stays where it is.
- Action Name
next- cell
$selectedCell- direction
direction
next.value >= 0- Variable
$selectedCell- Value
next.value
2.6.4 Move Selection
Move Selection is four Events, each making one call to Select Neighbor. Each is a 2D Direction Pressed. The Command it waits for shares this Logic’s name, Move Selection, so pick that Command in the Event’s second window. Then press its Direction on the Event’s block: Up, Right, Down or Left. Events: the When bars shows where that is.
Each call passes its direction’s name, bare, like Choose Terrain By Key’s terrains. Give each Event its call right after you add it, as you did there. Attach it to the Selection.
Lets the arrow keys move the Selection: each direction of the Move Selection Command (the arrow keys in the Input Manager) moves it one cell up, right, down or left. At the edge of the map it stays.
Any Object- direction
Up
- direction
Right
- direction
Down
- direction
Left
Window / UIUIX 64, Y 6444Cell OutlineX 64, Y 64#FF9D36Run the game and walk the ring right up to the left edge of the map, then press Left once more. It stays.
2.7 Painting
Now the land answers.
Choose Forest, and click the road right next to the camp. Pines grow there. Walk the ring somewhere with the arrows and press Enter, and that cell takes the brush too. Click the camp, and the ring goes there, but the tent stays.
A click on a cell does two things, and neither is painting. The cell makes itself the selected cell. Next it asks Maze Rules to paint. Maze Rules decides, writes the new cost into Maze Cells, and tells every cell. Each one shows the picture its cost calls for, the way it did when the map was laid out.
2.7.1 Paint Selected Cell
Paint Selected Cell is the one place the map’s costs change. First its If asks three questions at once, joined by &&. Is the selected cell not the camp? Not the tower? And is its cost not already the brush’s cost? Only when all three are true does it paint.
Painting is one Action, Set Data Cell, which writes one cell of a table: the cost column, in the selected cell’s row. Its Row box takes a row’s number or its name, and the card gives the name, made by dataRow. That turns the cell’s number into its row’s name: cell 12’s row is Cell 12. The If above it reaches the same row by number, with data(). Either works. Type each the way its card has it.
The Function sends terrainChanged after that, and every cell hears it. When nothing was painted, nothing is sent.
Paints the selected cell (the Project Global selectedCell) with the brush: its cost in Maze Cells becomes the brush terrain's cost from Terrains, and terrainChanged tells every cell. The Camp and the Tower are never painted, and a cell that already has that cost is left alone, so nothing is told.
$selectedCell != data('Maze Settings', 'rules', 'startCell') && $selectedCell != data('Maze Settings', 'rules', 'goalCell') && data('Maze Cells', $selectedCell, 'cost') != data('Terrains', $brush, 'cost')- Table
"Maze Cells"- Row
dataRow('Maze Cells', $selectedCell)- Column
"cost"- Value
data('Terrains', $brush, 'cost')
- Custom Event
terrainChanged
2.7.2 Change Terrain
Change Terrain, on Maze Rules, is where both ways of painting arrive, Enter and a click, and both end in the same call. Attach it to Maze Rules as soon as it’s made, because the click at the end of the next part needs it there.
The message it listens for, paintRequested, is a new Custom Event. Nothing sends it or listens for it yet, so the Add Event window doesn’t list it. Make its Event with Add Custom Event…, as you did for placedOnMap in Chapter 1. Paint Map Cell sends it in a moment.
Changes the terrain of the selected cell when the learner paints it: with a click or a touch on a cell (paintRequested, sent by the cell), or with the Paint Command (Enter in the Input Manager).
Any Object2.7.3 Paint Map Cell
Show Map Cell gets its new name now. Rename it Paint Map Cell, and its Mode, as you did Show Terrain Choice. Its first Event, On Placed on Map, stays as it is, and two Events are new.
Remember the UI Interaction each Map Cell kept in Chapter 1? This is what it was for. A click runs UI Activated: the cell sets $selectedCell to its own number, self.mapPlace.cell, and sends paintRequested. When terrainChanged arrives, the cell asks Cell Picture for its picture again, and shows it.
This time terrainChanged is waiting in the Add Event window, under Custom Events > Project Events, because Paint Selected Cell already sends it.
Every cell hears terrainChanged, and each one looks up its own cost. So only the cell you painted changes. The other 119 show what they showed before.
One cell of the map the learner can paint. It shows the picture its cost calls for, and draws its picture again whenever the terrain changes. Activating it (a click or a touch) selects it and asks Maze Rules to paint it with the brush. Its cell number is its Map Place cell, which Lay Out Map gives it.
Any Objectself.mapPlace- Action Name
place- cell
self.mapPlace.cell
- Position Relative To
Screen- X
place.x- Y
place.y
- Action Name
picture- cell
self.mapPlace.cell
- Frame
picture.value
- Variable
$selectedCell- Value
self.mapPlace.cell
- Custom Event
paintRequested
- Action Name
newPicture- cell
self.mapPlace.cell
- Frame
newPicture.value
The rename made every change on the Map Cell’s card, its Data Structure’s From Logic line included.
Window / UIUIX 64, Y 64-1Terrain TilesX 64, Y 64Paint Map CellShow Map CellMap PlaceRun the game and paint. Try the keys too: 3, the arrows, then Enter, and the cell under the ring turns to mud. Click the tower. The ring moves onto it, and the flag stays.
2.8 The Supplied Map Comes Back
Last, a way back.
Paint walls across the road until the map is yours, and then press D. Every cell goes back to the terrain it started with, and the ring goes back to the camp.
2.8.1 Restore Defaults
Restore Defaults, on Maze Rules, listens for the Restore Defaults Command, D. It doesn’t copy 120 costs back one by one. Reset Data Table puts the whole table back the way you wrote it in the editor, every cost from your import. After that, the ring goes back to the camp, and terrainChanged tells every cell to show its picture again.
Painting while the game runs never touches Maze Cells in your editor. The game paints its own copy. Reset Data Table sets that copy back to what you wrote.
Puts the supplied map back when the learner presses the Restore Defaults Command (D in the Input Manager): every cell gets the cost written in Maze Cells in the editor, the Selection goes back to the Camp, and every cell draws its picture again.
Any Object- Table
"Maze Cells"
- Variable
$selectedCell- Value
data('Maze Settings', 'rules', 'startCell')
- Custom Event
terrainChanged
The card for Maze Rules lists Change Terrain and Restore Defaults above Reset Trial, as the finished game has them. Yours land below it, and that’s fine. Each row of Attached Logic has a number, the order Maze Rules runs its Logic in. It matters only when two of them wait for the same Event, and none of these three do.
Run the game, paint a few cells, and press D.
Watch for each of these.
- Road is tan at the start, and the ring stands on the camp.
- Click Forest: its button turns tan, and Road’s goes pale. Click the mud picture: Mud turns tan. The map doesn’t change.
- Press 1, 2, 3 and 4 in turn, and Road, Forest, Mud and Wall each take the tan.
- Each press of an arrow key moves the ring one cell. Holding the key moves it once.
- At the top of the map Up does nothing, and at the left edge Left does nothing.
- Choose Forest and click the road right next to the camp. Pines grow there.
- Press Enter, and the cell under the ring takes the brush.
- Choose Wall and paint a cell: a gray rubble wall stands there.
- Click the camp or the tower. The ring moves there, and the tent or the flag stays.
- Press D. Every cell goes back to its first terrain, and the ring goes back to the camp.
- Cost still shows two dashes, and the Status line still says Paint terrain. The search comes in Chapter 3.
The buttons, the pictures and the keys all set $brush through Choose Brush, and the buttons color themselves when it changes. The arrow keys move $selectedCell through Find Grid Neighbor, and the ring follows. A click or Enter asks Maze Rules to paint. Paint Selected Cell writes the cost into Maze Cells, and every cell draws itself again.
Underneath is Chapter 1’s idea, one step deeper: nothing on the screen is painted. A number in Maze Cells changes, and the picture follows it. In Chapter 3, the search reads those same numbers. Every cell you step onto costs what you painted, and the camp, where you start, costs nothing.
2.9 If It Didn’t Work
Something may be off the first time, and that’s all right. Run the game, watch what it does, and follow the chain one piece at a time.
Clicking a terrain button does nothing? Find the UI Activated block in Choose Terrain. Its line should hold Choose Brush, with an arrow into it. A block standing apart does nothing, so join it with Connect to sequence. Did Choose Brush land by another Event? Right-click it there and choose Delete. Then right-click UI Activated’s Mode, choose Add unattached Action here, and add it again.
The keys choose, but the buttons never change color? Perhaps Choose Terrain has no Variable Changed Event, or it names another Global. It should say brush. Look at Highlight Terrain Choice’s If too: terrain == $brush, with the $.
All four buttons say Road 1? The placements have lost their terrains, which happens if Show Terrain Choice was deleted instead of renamed. Select each placement and type its terrain into Terrain, under Per Instance Variables, as in Chapter 1: Forest, Mud or Wall. The buttons are right again.
Pressing 1 to 4 does nothing? Look in the Input Manager, where each Choose Command needs its key. Choose Terrain By Key belongs on the Selection.
The ring won’t move at all? Perhaps Maze Settings still holds 0 in its rows column, the map’s height. Add Field put that 0 in the rules row, and a map 0 rows tall has no room for any step, so Find Grid Neighbor answers -1 every time. Type 10.
The ring moves the wrong way? Look at the Direction pressed on each Event’s block in Move Selection, and the name each one passes on.
The ring jumps to the far side of the map at an edge? Look at Find Grid Neighbor’s If. It needs all four tests, joined by &&. With || between them, one true test is enough, and the ring wraps.
A click moves the ring but paints nothing? Follow the chain. Is Change Terrain on Maze Rules? Does it listen for paintRequested, spelled the way Paint Map Cell sends it? Is Paint Selected Cell’s Set Data Cell joined inside its If? And does Paint Map Cell have its terrainChanged Event? Without that Event, the cost in Maze Cells changes, but the picture never follows it.
Each of these is one small fix. Make it, run the game again, and you’re back with the chapter. The catch-up download in the Goal is this chapter’s game, finished, to compare with yours.
The controls are yours to choose. Some players would rather keep their hand on the letters. Give Move Selection a second set of keys: I for Up, J for Left, K for Down and L for Right. In the Input Manager, press Add Keybinding under Move Selection. Pick the direction in the new row’s list, click its No Input Assigned button, and press the key. Run the game and walk the ring with your new keys. Move Selection never changed. It listens for the Command, and the Command now has two keys for each way.
You can paint the map now, and the compass still waits at the camp. In Chapter 3, Step wakes the search.