Tutorials · Worlds and Levels · Chapter 4

Tiles that do things

When a tile should do something

The torch

1. With scenes/crypt.ron open, press Ctrl+S. Choose File → New scene: an empty scene takes the crypt’s place.
2. Double-click art/torch.png in Assets. The Sprite sheet tab opens on it. Press Detect grid: Cell reads 16 and 16, and the line under it 2 x 1 cells.
3. Drag across both cells in the picture: Selected 2 x 1. Under Clips, press From selection; name the clip burn, 6 fps, Loop; and press Generate 1. A file, art/torch.anim, appears beside the picture.

Detect grid

Reads the cell size off the picture’s own transparent gaps, and fills in Cell; the line under it counts the cells. Typing Cell does the same by hand.

From selection and Generate 1

A drag across the picture’s cells selects them; From selection makes a clip of them, to name and give its frames a second and its loop. Generate 1 writes the clips listed into a .anim beside the picture.

1. Press + Add node and choose Animated Sprite. Rename it torch.
2. In its Sprite, drag art/torch.png onto Texture, set Size to 16, 16 and Sort Layer to Props, and tick Unshaded. Leave Anchor at 0.5, 0.5: a tile stands its copy on the middle of its cell.
3. In its Animated Sprite, drag art/torch.anim onto Animations and set Clip to burn.
4. Press Add component and choose LightComponent. Set its Color to 1.0, 0.7, 0.4, its Radius to 176 and its Intensity to 3: a warm pool round the flame. Leave the rest as it comes, a Point.
5. Right-click torch in the Hierarchy and choose Save as artifact…. In the save dialog, make a folder called artifacts, open it, and save the file as torch.artifact. Select the torch left in the scene, press Delete, and press Delete in the box that asks.
6. Double-click scenes/crypt.ron in Assets to open the crypt again. The editor asks Save the open scene?: choose Discard: the new scene is never saved, and its Save is greyed. Click the Viewport tab.

Three tiles that do things

1. Select halls and click the Tilemap tab. In the picker, click tile #52, the first of the four water tiles.
2. Under Animation, press Add frame three times: the new frames are #53, #54 and #55, each the cell after the last, and each lasts 0.20s as it comes.
3. Set Tint to 0.85, 0.95, 1.0, alpha 0.75: the water cooled a little and made see-through, so the back wall shows through it.

1. Click tile #56, the spikes. Under Data, press Add value and choose Bool. Type hurt over the new row’s name, key, press Enter, and tick its box.
2. Set Art origin’s y to 0.25, and Z offset to 2.

1. Click tile #57, the torch’s bracket. Drag artifacts/torch.artifact from Assets onto Scene’s slot.

A tile’s Tint

A colour multiplied into the tile’s art wherever it is painted, alpha included, on top of the map’s own Color. White, as every tile comes, changes nothing. The water’s alpha 0.75 lets a quarter of what is behind it through.

A tile’s Art origin

Moves where the tile’s art is drawn in its cell, in cells, across and down; the cell it is painted in stays where it is. The spikes’ y 0.25 sinks their art a quarter cell, 4 units, into the pit’s floor.

A tile’s Z offset

Added to the tile’s order within the map’s Sort Layer, as its layer’s z is. The spikes’ layer is at z 0 and the water’s at 1; the spikes’ 2 puts them in front of the water.

A tile’s Animation, and Add frame

The frames the tile plays, in order, each with its cell and its time. The tile’s own cell is the first frame and lasts as long as the first added one; so #52 plays #52, #53, #54 and #55, 0.2 seconds each, round in 0.8. Add frame adds a frame at 0.20s, its cell the one after the last frame’s, the tile’s own cell counted: on #52, #53, then #54, then #55; a frame’s cell and time can be dragged or typed, its arrows move it, and its bin drops it.

A tile’s Data, and Add value

Named values a script reads off the tile wherever it is painted. Add value offers Bool, a box to tick, and Int, Float and Text, which chapter 14 uses; each row starts named key, and a name is kept when its box loses the cursor.

A tile’s Scene

A scene or an artifact the tile places instead of drawing art: drop one on its slot, click the slot to clear it. While the game plays, each cell painted with the tile holds a copy of it, a child of the map at the cell’s middle, named for its cell, tile 7,-6 and so on. In the editor the cells show a marker. The band says Places a scene, and the slot shows the start of the id.

A tile’s Draws as

Points the tile at another one: every cell painted with it draws that tile’s art instead. Typing the tile’s own number back clears it; 0 draws nothing. On a copy, set #56’s to #51: the pit’s six cells all draw the worn stone, and none draws a spike. It is for a sheet whose art moves after rooms were painted on it; chapter 14’s dungeon uses it.

Collision layers by name

1. Choose File → Project settings… and click the Physics tab.
2. Press Show all layers. Type pilgrim beside 0 and rubble beside 1. Press it again: the two named layers are listed, and the matrix under them.

Layer names

What the thirty-one collision layers are called, project-wide. A scene keeps a layer as its number, so a name changes nothing about what collides; it is what every picker of layers shows. Show all layers lists the unnamed ones too, to name one.

The Collision matrix

Which pairs of named layers collide: a ticked pair does, an unticked pair passes through each other. A body meets a collider, or a tile layer, only when the pair of their layers is ticked here. Every pair comes ticked.

Layers that do things

1. In the Layers band, open ground’s gear and tick Occluder; do the same for pillars.
2. Click ground’s row and press +: an empty layer goes in over ground and lights. Double-click its name and rename it ledges. Press + again for each of the other four, renaming each in the table’s order: each goes in over the one before.
3. Set each layer’s flags as the table says, and paint it. On ledges, click the stone row in the Terrains band and draw a Line: the terrain lays its two ends and its middle.

A layer’s One-way

Its tiles hold a body from above and let it through from below and from the sides: he jumps up through a ledge and lands on it. Greyed until Solid is ticked; the gear shows 1.

A layer’s Blocks nav

Its tiles are walls to agents finding their way round the map. Its own flag: ticking Solid does not tick it, and a new layer comes without it. Nothing in Hollowmere walks by navigation, so the new layers leave it off.

A layer’s Occluder

Its tiles cast shadows from every light. ground and pillars are the walls; the gear shows O.

A layer’s Collision layers

Which collision layers the layer’s Solid and Blocks-nav tiles are on. Every layer, ticked as a layer comes, is all of them. Unticked, the project’s named layers appear to tick, starting from the first alone. A body meets them only when the Collision matrix pairs its layer with one of theirs; any other passes through, as through a Collider. Greyed on a layer that is neither Solid nor Blocks nav, whose tiles are on no collision layer. The gear’s hover names them.

A hidden layer

Its eye shut. The eye’s hover says what that does: “Hide this layer, in the game too: it draws nothing, casts no shadow and places no scene tiles, and still collides and blocks navigation and sight as its flags say”. edge is a wall he cannot see, in the gap west of the top step, so he cannot walk off the stair into nothing.

A layer’s z, as an order

Layers draw in their z order inside the map’s Sort Layer, and a tile’s Z offset is added to its layer’s: the back wall and the pillars at -1; the floor, the ledges, the spikes’ row and the torches at 0; the water at 1, in front of them; and the spikes lifted by their 2 over the water.

Light, a checkpoint and the crypt’s bounds

1. Select crypt, press + Add node and choose Ambient Light. Rename it ambient and set its Color to 0.30, 0.30, 0.45.
2. Select crypt again, press + Add node and choose Node. Rename it checkpoint and set its Position to 1120, 0, on the halls’ floor west of the pit.
3. Select crypt again, press + Add node and choose Camera Confiner. Rename it crypt-bounds, and press Fit to tilemap in its Confiner. Press Ctrl+S.

Fit to tilemap

Under a Confiner: sets Bounds to the box of a map’s painted cells, every layer, hidden ones too, and moves the node to the box’s middle, as one step to undo. The crypt’s box is x -32 to 1632 and y -256 to 112: Bounds 1664, 368, at 800, -72. With one map to fit, it is a button; with several, a menu of their names; with none, greyed, and its hover says “No tilemap outside this node has painted cells”. When it cannot fit, the status line says why: “This Confiner already fits that tilemap”, “This node’s parent is scaled to nothing, so there is nowhere to move it to” or “That tilemap has no painted cells outside this node to fit to”.

The Confiner’s Bounds and Blend

The room the view is kept inside, a size centred on the node, and the seconds the view slides in over when the camera arrives in it; 0, as it comes, cuts.

The pilgrim’s script

1. In Assets, click Assets in the path bar, so the script is written at the project’s top, then click Create, choose New script, type pilgrim and press Enter. Click the Code tab, then pilgrim.rgs in its Scripts list, replace everything in it with the script below, and press Ctrl+S. Click the Viewport tab.
2. Select the crypt’s pilgrim, press Add component and choose Pilgrim.
3. Its Map row is empty: click it and choose halls. Click Checkpoint and choose checkpoint. Press Ctrl+S.

/// The pilgrim in the crypt. Down drops him through a ledge he stands on,
/// and a tile that hurts sends him back to the checkpoint.
component Pilgrim {
    /// The crypt's tilemap: the halls, whose tiles he reads.
    #[node_path]
    map: i32 = 0,
    /// Where a tile that hurts sends him back to.
    #[node_path]
    checkpoint: i32 = 0,

    fn loop() {
        // Down (S, or the down arrow) on a ledge drops him through it.
        if pressed("down") {
            drop_down();
        }
        // The cell he stands in, read 4 above his feet: his feet are on the
        // line between two cells, and the one under the line is the floor.
        // A tile there on the hazards layer whose Data says hurt sends him
        // back to the checkpoint.
        let cell = cell_at(node(map), position() - vec2(0.0, 4.0));
        if tile_flag(node(map), "hazards", cell, "hurt") {
            move_to(position_of(node(checkpoint)));
        }
    }
}

cell_at

The cell of a map that a place in the world falls in, as a column and a row in whole numbers. Here, the halls’ cell he stands in.

tile_flag

Reads a named Data row off the tile in a cell of a layer, as true or false: a Bool as it is, a number as not 0, text as false; false when the cell is empty or the tile has no such row. Here, whether the hazards tile he stands in says hurt.

drop_down

Asks his Character Body to drop through the one-way ledge he stands on. On solid ground or in the air it does nothing.

move_to and position_of

Puts this node at a place in the world, and reads where another node is: here, the checkpoint’s place.

pressed

Whether an action went down this step: down is S or the down arrow.

node, position and vec2

The node a #[node_path] field picked, as the other calls take it; where this node is, as the step began; and a pair of numbers, a place or a distance.

What the tiles do

1. With scenes/crypt.ron open, press F5: Play runs the open scene. Walk him east along the halls.

1. Press F5 again to stop.

The crypt’s tiles and layers

Check it works