EA Source Code Insights - Iron Curtain

Insights from EA’s Original Source Code

Repository: https://github.com/electronicarts/CnC_Red_Alert (GPL v3, archived Feb 2025)

Code Statistics

290 C++ header files, 296 implementation files, 14 x86 assembly files
~222,000 lines of C++ code
430+ #ifdef WIN32 checks (no other platform implemented)
Built with Watcom C/C++ v10.6 and Borland Turbo Assembler v4.0

Keep: Event/Order Queue System

The original uses OutList (local player commands) and DoList (confirmed orders from all players), both containing EventClass objects:

// From CONQUER.CPP
OutList.Add(EventClass(EventClass::IDLE, TargetClass(tech)));

Player actions → events → queue → deterministic processing each tick. This is the same pattern as our PlayerOrder → TickOrders → Simulation::apply_tick() pipeline. Westwood validated this in 1996.

Keep: Integer Math for Determinism

The original uses integer math everywhere for game logic — positions, damage, timing. No floats in the simulation. This is why multiplayer worked. Our FixedPoint / SimCoord approach mirrors this.

Keep: Data-Driven Rules (INI → MiniYAML → YAML)

Original reads unit stats and game rules from .ini files at runtime. This data-driven philosophy is what made C&C so moddable. The lineage: INI → MiniYAML → YAML — each step more expressive, same philosophy.

Keep: MIX Archive Concept

Simple flat archive with hash-based lookup. No compression in the archive itself (individual files may be compressed). For ic-cnc-content: read MIX as-is for compatibility; native format can modernize.

Keep: Compression Flexibility

Original implements LCW, LZO, and LZW compression. LZO was settled on for save games:

// From SAVELOAD.CPP
LZOPipe pipe(LZOPipe::COMPRESS, SAVE_BLOCK_SIZE);
// LZWPipe pipe(LZWPipe::COMPRESS, SAVE_BLOCK_SIZE);  // tried, abandoned
// LCWPipe pipe(LCWPipe::COMPRESS, SAVE_BLOCK_SIZE);   // tried, abandoned

Leave Behind: Session Type Branching

Original code is riddled with network-type checks embedded in game logic:

if (Session.Type == GAME_IPX || Session.Type == GAME_INTERNET) { ... }

This is the anti-pattern our NetworkModel trait eliminates. Separate code paths for IPX, Westwood Online, MPlayer, TEN, modem — all interleaved with #ifdef. The developer disliked the Westwood Online API enough to write a complete wrapper around it.

Code path for 640x400 display mode with special VGA fallback
#ifdef FIXIT_CSII for Aftermath expansion — comment explains they broke the ability to build vanilla Red Alert executables and had to fix it later
Developer comments reference “Counterstrike” in VCS headers ($Header: /CounterStrike/...)
MPEG movie playback code exists but is disabled
Game refuses to start if launched from f:\projects\c&c0 (the network share)

Coordinate System Translation

For cross-engine compatibility, coordinate transforms must be explicit:

#![allow(unused)]
fn main() {
pub struct CoordTransform {
    pub our_scale: i32,       // our subdivisions per cell
    pub openra_scale: i32,    // 1024 for OpenRA (WDist/WPos)
    pub original_scale: i32,  // original game's lepton system
}

impl CoordTransform {
    pub fn to_wpos(&self, pos: &CellPos) -> (i32, i32, i32) {
        ((pos.x * self.openra_scale) / self.our_scale,
         (pos.y * self.openra_scale) / self.our_scale,
         (pos.z * self.openra_scale) / self.our_scale)
    }
    pub fn from_wpos(&self, x: i32, y: i32, z: i32) -> CellPos {
        CellPos {
            x: (x * self.our_scale) / self.openra_scale,
            y: (y * self.our_scale) / self.openra_scale,
            z: (z * self.our_scale) / self.openra_scale,
        }
    }
}
}

Iron Curtain — Design Documentation