Coordinates and Rendering Model

Screen size

The game canvas is 320 x 180 pixels.

Coordinate system

• (0, 0) is the top-left corner of the screen

• x increases to the right

• y increases downward

• All drawing functions use pixel coordinates

(0,0) ---------------------- (319,0)
  |                            |
  |                            |
  |         320 x 180          |
  |                            |
  |                            |
(0,179) --------------------- (319,179)

Sprite sheet layout

The engine uses a single sprite sheet made of 8 x 8 pixel tiles.

Property	Value
Sprite size	8 x 8 pixels
Sheet size	128 x 128 pixels
Sprites per row	16
Total sprite slots	256 (0 – 255)

Sprite indexing

Sprites are numbered left-to-right, top-to-bottom:

Row 0:   [ 0][ 1][ 2][ 3] ... [15]
Row 1:   [16][17][18][19] ... [31]
Row 2:   [32][33][34][35] ... [47]
...
Row 15:  [240] ...           [255]

• Sprite 0 = top-left corner of the sheet

• Sprite 1 = next sprite on the same row

• Sprite 16 = first sprite on the second row

To find a sprite at column c and row r:

index = r * 16 + c

Multi-tile sprites

You can draw sprites that span multiple tiles using the width and height parameters of the sprite() function. For example, a 16 x 16 pixel character uses width = 2, height = 2.

-- Draw a 2x2 tile sprite (16x16 pixels) starting at index 0
sprite(0, x, y, 2, 2)

The engine draws a rectangular block of tiles from the sprite sheet starting at the given index.