orni_attack/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

This is an Asteroids-style game originally written in Turbo Pascal 7 for DOS, now being converted to modern C++ with SDL2. The game features a spaceship that must avoid and destroy enemies ("cosinus mesisinus" mounted in UFOs/ORNIs). The codebase contains both the original Pascal implementation and the in-progress C++ port.

Language: The code and comments are in Catalan/Valencian.

Build Commands

macOS:

make macos
./bin/asteroids_macos

Linux:

make linux
./bin/asteroids_linux

Both commands compile from source/*.cpp with -std=c++11 -Wall -O2 and link against SDL2.

Architecture

Code Structure

• source/ASTEROID.PAS - Original Turbo Pascal 7 implementation (DOS)
• source/asteroids.cpp - C++ port using SDL2 (in progress)

Core Data Structures

The game uses polar coordinates (ipunt) for geometric objects:

• ipunt - Polar coordinate point (radius r, angle angle)
• punt - Cartesian coordinate point (x, y)
• triangle - The player's ship (3 polar points + center + angle + velocity)
• poligon - Generic polygon for enemies and bullets (vector of polar points + center + angle + velocity + rotation)

Key Game Constants

Defined in asteroids.cpp:

• Screen bounds: MARGE_DALT (20), MARGE_BAIX (460), MARGE_ESQ (20), MARGE_DRET (620)
• MAX_ORNIS (15) - Maximum enemies
• MAX_BALES (3) - Maximum bullets
• VELOCITAT (2), VELOCITAT_MAX (6) - Speed constraints

Rendering System

The original Pascal code used VGA Mode 13h (320x200, 256 colors) with custom bit-packed framebuffer:

• pvirt - Virtual screen buffer (38400 bytes)
• posa(x,y,color) - Set pixel in virtual buffer (bit-packed)
• llig(x,y) - Read pixel from virtual buffer
• volca() - Flip virtual buffer to VGA memory
• Line drawing using Bresenham algorithm

The C++ port uses SDL2 for rendering.

Game Mechanics

• Movement: Ship uses polar velocity - angle determines direction, velocity determines speed
• Collision: Line drawing returns collision state; rota_tri() returns 1 on pixel collision
• Death sequence: Ship shrinks (nau.p*.r decreases), explodes into debris (chatarra_cosmica), then respawns after 250 frames
• Enemies: orni[] array of polygons with autonomous movement, random angle adjustments
• Bullets: Only one bullet active at a time (bales[1].esta flag)

Pascal-to-C++ Conversion Notes

The C++ file contains hybrid Pascal/C++ syntax that needs completion:

• Lines 63-450 are uncommented Pascal code
• Pascal procedures/functions need conversion to C++ equivalents
• Assembly blocks (waitretrace, VGA mode setting) need SDL2 replacements
• Turbo Pascal keyboard handling (teclapuls, instalarkb) needs SDL event system
• Memory management (getmem, pointer segments) needs modern C++ approach

Game Controls (from README)

• Up Arrow: Accelerate
• Down Arrow: Brake
• Right Arrow: Rotate clockwise
• Left Arrow: Rotate counterclockwise
• Space: Fire
• Esc: Exit

Development Notes

• The conversion is incomplete - much Pascal code remains in comments
• Focus on SDL2 for cross-platform graphics/input instead of DOS VGA/keyboard
• Original used bit-packed monochrome framebuffer; consider SDL surfaces or textures
• Preserve the polar coordinate geometry system - it's core to the game's physics