Visualizer config fixes

[mpragnay]

Changed visualize.c defaults to ini configs so it's easier to debug

[greptile-apps]

Greptile Summary

Refactored visualizer configuration handling by moving INI file parsing from eval_gif() to main(), allowing default values from the config file to be used throughout the visualizer. Extended the INI parser to support visualizer-specific options (show_grid, show_lasers, obs_only, num_maps) and added CLI arguments for collision/offroad behavior and dynamics model.

Key Changes:

• Moved INI parsing from eval_gif() to main() for centralized configuration
• Expanded eval_gif() signature from 14 to 22 parameters to accept all configuration values explicitly
• Simplified scenario_length logic by removing fallback chain
• Added visualizer config fields to env_init_config struct
• Added CLI argument parsing for --collision-behavior, --offroad-behavior, and --dynamics-model

Issues Found:

• Pre-existing bug: INI parser uses atoi() on control_mode and init_mode, which are string enums in the INI file (e.g., "control_vehicles"). This will always evaluate to 0. Python correctly handles the string-to-int conversion, but the C visualizer may not work correctly with non-default modes.

Confidence Score: 4/5

• This PR is safe to merge with one pre-existing bug noted
• The refactoring is well-structured and follows good separation of concerns by centralizing config parsing in main(). The changes are primarily organizational with expanded parameter passing. However, a pre-existing bug exists where control_mode and init_mode string values from the INI file are incorrectly parsed using atoi() which always returns 0 for string enum values. This bug predates this PR but affects the visualizer's ability to use non-default control/init modes.
• The env_config.h file has a pre-existing bug with control_mode/init_mode parsing that should be fixed in a future PR

Important Files Changed

Filename	Overview
pufferlib/ocean/env_config.h	Added four new configuration fields (num_maps, show_lasers, show_grid, obs_only) to support visualizer configuration from INI file. Parser logic follows existing patterns.
pufferlib/ocean/drive/visualize.c	Refactored to move INI parsing from eval_gif() to main(), expanded eval_gif() signature with 8 additional parameters. Added CLI argument parsing for --collision-behavior, --offroad-behavior, and --dynamics-model.

Sequence Diagram

sequenceDiagram
    participant main
    participant ini_parser
    participant eval_gif
    participant Drive_env
    
    Note over main: Program starts
    main->>ini_parser: ini_parse("drive.ini", handler, &conf)
    ini_parser-->>main: Parse all config fields
    Note over main: Initialize defaults from conf:<br/>show_grid, obs_only, lasers,<br/>goal_radius, init_steps, etc.
    
    main->>main: Parse CLI arguments<br/>(override config values)
    
    main->>eval_gif: eval_gif(22 parameters including<br/>dynamics_model, collision_behavior,<br/>reward values, map_dir, etc.)
    
    Note over eval_gif: No longer parses INI file
    
    eval_gif->>Drive_env: Initialize Drive struct<br/>with all configuration values
    
    eval_gif->>eval_gif: allocate(&env)
    eval_gif->>eval_gif: c_reset(&env)
    eval_gif->>eval_gif: Render frames and<br/>generate video output
    
    eval_gif-->>main: Return status
    main-->>main: Exit

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[greptile-apps]

Additional Comments (1)

1. pufferlib/ocean/env_config.h, line 90-95 (link)

   logic: Pre-existing bug: atoi() returns 0 for string values like "control_vehicles" and "create_all_valid" in the INI file. The Python code correctly converts strings to integers (drive.py:90-109), but the C INI parser doesn't handle these string enum values.

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[daphne-cornelisse]

@mpragnay what is the advantage of doing this? We can just directly take them from the drive.ini (see main)