UOX3.org

By: Otim Pyre | Date: 3/11/2011
Updated & Simplified with UOP Conversion

Overview
To add a new animated item (like a custom moongate), you need to modify three client files and optionally convert them to UOP format if your client uses .uop instead of .mul.

You’ll be editing:

art.mul & artidx.mul – holds the graphics

tiledata.mul – item behavior and flags

animdata.mul – animation frames & speed

Optionally: Convert .mul files to .uop if your client uses artLegacyMUL.uop

Step 1 – Add Frames to art.mul
Open UOFiddler, go to the Art tab.

Locate 15 unused consecutive slots, e.g., starting at 0x2379.

Prepare your animation frames as 1.bmp through 15.bmp in a folder (e.g., portal).

Right-click each slot → Replace → select the appropriate .bmp.

After all frames are added, right-click → Save.

Saved location:
You'll get:

art.mul

artidx.mul

Copy these files to your UO directory if you're using a MUL-based client.

Step 2 – Edit tiledata.mul
Go to the TileData tab.

Enable “Save directly on changes.”

Find your ID (e.g., 0x2379).

For all frames, set:

Weight: 255 (immovable)

Quality: 29 (light source enabled)

Flags: Check:

Animation

LightSource

ArticleA

Unknown3

Name: Portal

Use ↑/↓ keys to move through and verify each frame.

File saved to:
Step 3 – Define Animation in animdata.mul
Go to the Animdata tab.

Scroll to the last group before your ID (e.g., 0x237).

Right-click → Add → enter 0x2379 → press Enter.

On the right:

Start Delay: 0

Frame Delay: 3 (higher = slower)

Add each frame ID (0x2379 to 0x2387) manually and click Add each time.

Use Start/Stop to preview the animation.

Click Save.

File saved to:
Step 4 – Convert .MUL to .UOP (If Needed)
If your Ultima Online client uses .uop files (like artLegacyMUL.uop), you must convert the edited .mul files to .uop.

Tools Required:
LegacyMULConverter

UOClientTools

Or other verified UOP converters (some are command line, some GUI-based)

Convert these:
art.mul + artidx.mul → artLegacyMUL.uop

tiledata.mul → tiledataLegacyMUL.uop

animdata.mul → animLegacyMUL.uop

General steps:
Open your converter tool.

Select the .mul files you just edited.

Follow prompts to generate .uop versions.

Backup your current .uop files.

Replace with the newly generated .uop files in your UO client folder.

Some clients ignore .mul files if .uop versions exist — so conversion is mandatory for those.

Final Summary
After replacing the updated .mul or .uop files in your UO folder:

Your custom animated object (e.g., moongate) will appear in-game.

You won’t overwrite existing art.

Backup your original files in case you need to revert.