Planet Blupi — Technical Documentation

This documentation describes the internal workings of Planet Blupi (Epsitec SA, 1997). It is aimed at developers working with this codebase or reverse-engineering related games (especially Speedy Blupi, which is authored by the same team and shares core design).

Overview

Game Overview — what is Planet Blupi, technical summary, gameplay pillars
History & Relation to Speedy Blupi — origin, fork context, shared code

Architecture

System Architecture — class diagram, subsystem relationships, tick lifecycle
Source Files Reference — every .cpp/.h file explained

Engine Internals

Data Structures — Cellule, Blupi, Move, Term, DescFile in full detail
Game Phases (Screens) — WM_PHASE_* messages, screen lifecycle, flow diagram
Rendering — image channels, coordinate system, draw order, CPixmap
Pathfinding (A*) — CPileTriee, CheminCherche(), obstacle tables
Fog of War — quadrant bit encoding, 15 fog patterns, API
Minimap — generation, colour coding, click-to-scroll
Demo Recording & Playback — DemoHeader, DemoEvent, replay mechanism
Undo System — single-step undo in the level editor

World (Map)

World File Format (.blp) — binary layout, DescFile header, versioning
World Grid — 200×200 cells, coordinate system, viewport, scrolling
Terrain & Auto-tiling — floor tiles, regions, arrange.cpp, tableSee
Object Layer — object categories, channels, passability

Characters

Character Overview (Blupi struct) — every field of the Blupi structure
Player Character (Blupi) — energy, spawning, selection, idle animations
Enemies — spider, virus, tracks, robot, bomb, electro — AI & behaviour
Vehicles — boat, jeep, armour — boarding, movement, exits
Animation Actions (ACTION_*) — all codes for all character types
Task Interpreter (GOAL_*) — all opcodes, parameters, GoalNextOp(), WM_ACTION_* mapping

Gameplay

Win Conditions (Term) — Term struct, IsTerminated()
Toolbar Buttons (BUTTON_*) — all 35 actions, WM_ACTION_* mapping
Movement Directions (DIRECT_*) — 8-direction system, GetVector()
Skill Levels — easy / normal / hard
Regions (World Themes) — 4 visual themes, sprite sheet swap
Cheat Codes — invincible, super

Assets

Image Assets — all .blp images, channels CHBACK–CHBIGNUM
Sound Effects (SOUND_*) — all 85 SFX with descriptions
Music Tracks — 10 MIDI tracks
Data Files — data/ directory, mission numbering
Movie Sequences — AVI files, fallback images

User Interface

Windows Messages (WM_*) — complete WM_ACTION_, WM_BUTTON_, WM_PHASE_* tables
Mouse Cursor Sprites (SPRITE_*) — 14 cursor sprites
Statistics Panel — contents, update, rendering
Error Codes (ERROR_*) — 8 error states

Platforms

Build System — CMake, dependencies, target platforms
Configuration File — data/config.def, all keys
Localisation — language packs, string resources
Web (Emscripten) — IndexedDB persistence, export/import

Speedy Blupi Reference

Relation to Speedy Blupi — fork context, shared elements, key differences
actions.h Reference — complete enum listings for decompilation use