Ceilings Mod for Project Zomboid B42

Build ceilings at the z+1 level above your character! This mod integrates with Project Zomboid's new B42 building system to enable ceiling construction with support constraints.

Features

• Ceiling Construction: Build ceilings one level above your current position
• Realistic Validation: Ceilings require proper structural support (walls or adjacent floors)
• Visual Feedback: Ghost preview shows where ceilings can be built along with ground ghost for reduced eyeball damage
• Extensible System: Easy for modders to add their own ceiling pieces
• Stands Alone: Comes out-of-the-box with a metal and a wooden ceiling entity

How It Works

The mod uses a multi-hook approach to intercept and modify the building system:

1. Entity Detection (ISBuildPanelClientHook.lua)

• Detects ceiling entities by checking for ceiling tag in recipes
• Flags detected entities with isCeilingBuild = true
• Stores z-level information for other hooks
• Detected entities are run through custom rendering for building ghost + guide sprite

2. Building Action (ISBuildActionClientHook.lua)

• Intercepts build commands for ceiling entities
• Redirects construction to z+1 level
• Ensures ceiling is built at correct elevation

3. Server Validation (BuildCeilingServer.lua)

• Validates ceiling placement with structural requirements
• Checks for proper support (walls or adjacent floors)
• Handles ceiling creation and integration

Current Status

Working Features:

• Ceiling detection via recipe tags
• Building at z+1 level
• Correct validation logic with structural requirements
• Ghosts have mirrored validation state

Known Limitations:

• Ceilings built will sometimes not render correctly (appear/disappear) from the player perspective without leaving the area or re-loading the save.

Validation Rules

Ceilings can be built when:

1. Adjacent ceiling floor exists - in any direction at the same level
2. Wall directly below - any wall (WallN or WallW) at ground level (z-1)
3. West-facing wall support - WallW at x+1,z-1 reaches west to provide support
4. North-facing wall support - WallN at y+1,z-1 reaches north to provide support

For Modders: Adding Your Own Ceiling Pieces

To make your building pieces work with the ceiling system, add these components to your entity scripts:

1. Add Ceiling Tag to CraftRecipe

component CraftRecipe
{
    tags = ceiling,  // <- This tag enables ceiling detection
    // ... rest of your recipe
}

2. Add Validation and Creation Hooks to SpriteConfig

component SpriteConfig
{
    OnIsValid = BuildRecipeCode.ceiling.OnIsValid,  // <- Ceiling validation
    OnCreate  = BuildRecipeCode.ceiling.OnCreate,   // <- Ceiling creation
    // ... rest of your sprite config
}

Complete Example

Here's a complete entity script for a custom ceiling:

module Base
{
    entity MyCustomCeiling
    {
        component SpriteConfig
        {
            isThumpable     = false,
            OnIsValid       = BuildRecipeCode.ceiling.OnIsValid,
            OnCreate        = BuildRecipeCode.ceiling.OnCreate,
            
            face W
            {
                layer
                {
                    row = your_sprite_here,
                }
            }
        }
        
        component CraftRecipe
        {
            tags            = ceiling,  // <- Essential for detection!
            time            = 150,
            category        = Ceilings,
            SkillRequired   = Woodwork:3,
            xpAward         = Woodwork:30,
            inputs
            {
                // Your required materials
            }
        }
    }
}

That's it! Your ceiling piece will automatically:

• Be detected by the mod
• Build at z+1 level
• Use proper validation rules
• Show correct ghost preview

Technical Details

Hook Priority

The mod uses a careful hook sequence:

1. ISBuildPanel detects ceiling entities first
2. ISBuildAction handles actual building when clicked
3. Server validation runs when needed

Compatibility

• Works with any entity using the ceiling tag system
• Doesn't interfere with vanilla building
• Compatible with other building mods

Support

For issues or questions:

• Check console logs if ceiling detection isn't working
• Ensure your entities have the correct tags = ceiling property
• Post a new issue here

Version History

• v1.11: Updated for B42.13+ multiplayer compatibility -- Changed Is() API calls to has() for property checking -- Removed empty client-side patch file causing require warnings -- Tested for multiplayer server deployment
• v1.10: Fixed ghost sprite to mirror IsValid status of build sprite - thanks Alex for pointing me in the right direction
• v1.00: Initial release with working ceiling system -- Full z+1 building support -- Extensible tag-based detection

To-Do

• Nothing ATM!