Skip to content

LevelDataStorage.md

Latest commit

 

History

History
116 lines (80 loc) · 2.57 KB

LevelDataStorage.md

File metadata and controls

116 lines (80 loc) · 2.57 KB

Level Data Storage Using Colors (RGBA)

This document describes a level storage format based on images, where each pixel represents a single map cell, and its RGBA color encodes the properties of that cell.

Map Size

  • The map size is defined by the image resolution in pixels.
  • Both width and height must be greater than 0.
  • Each pixel corresponds to exactly one tile on the map.

Design Goals

  • Tile ID is defined by color, making levels easy and intuitive to create.
  • Additional data is stored in a way that does not affect visual readability.
  • The format must be:
    • unambiguous,
    • easy to parse,
    • editable using standard image editors.

Channel Usage

RGB Channel – Tile ID (Visible Color)

The RGB channels are used only to define the tile id.

  • Each id (0–7) is mapped to a fixed, clearly distinguishable color.
  • Level designers work directly with colors, without needing to think about bit values.

Example color mapping:

ID Meaning RGB Color
0 Default Tile (0, 0, 0)
1 Path Straight (255, 255, 0)
2 Path Turn (0, 255, 255)
3 Factory (0, 255, 0)
4 Boiler (0, 0, 255)
5 Splitter (255, 0, 0)
6 Merger (255, 0, 255)
7 Obstacle (255, 255, 255)

⚠️ Colors must be exact (no anti-aliasing or lossy compression).

Alpha Channel – Rotation and Power

The Alpha (A) channel stores additional numerical data.

Bit Layout (8 bits)

PPPPPP RR
Bits Description
RR (2 bits) rotation (0–3)
PPPPPP (6 bits) power (0–63)
  • power uses inverted logic for better defaults:
    • power = 0 is stored as 111111
    • power = 63 is stored as 000000
  • Alpha value 255 still represents full opacity, ensuring visual consistency in image editors.

Encoding Rules

storedPower = 63 - power
alpha = (storedPower << 2) | rotation

Example

power = 0
rotation = 1

storedPower = 63 -> 111111
rotation = 1 -> 01

Alpha bits: 11111101
Alpha value: 253

Data Decoding

  1. Read pixel color (R, G, B, A)
  2. Determine id from (R, G, B)
  3. Extract from Alpha:
rotation = A & 0b00000011
power = 63 - ((A >> 2) & 0b00111111)

Notes

  • Use lossless formats only: PNG, BMP, QOI
  • Disable:
  • anti-aliasing,
  • color correction,
  • lossy compression.
  • Providing a color palette or template image for designers is strongly recommended.