====== Custom object (decomp) ======

This page describes how to create a custom object with custom 3D model and custom behavior using the [[Decompilation project|Super Mario 64 decompilation project]].

===== Export 3D model (Fast64) =====

In Blender, install the [[Fast64]] plugin, select your object you want to export, open the Fast64 menu and expand **SM64 Geolayout Exporter**. Ensure to select C as the export.

Choose **Actor Data** as the export type and provide a group name such as **common0**. The exported model requires a unique folder name such as **custom_platform**. For the geolayout name, it's advised to use the same as the folder name and "_geo" appended, such as **custom_platform_geo**.

Ensure the newly created model.inc.c file is included in actors/<group>.c file, such as in **actors/common0.c** (should be done by Fast64 exporter).

Ensure the newly created geo_header.h file is included in actors/<group>.h file, such as in **actors/common0.h** (should be done by Fast64 exporter).

Ensure the newly created geo.inc.c file is included in actors/<group>_geo.c file, such as in **actors/common0_geo.c** (should be done by Fast64 exporter).

===== Load custom model =====

It's a good idea to give your 3D model a unique name, such as **MODEL_CUSTOM_COIN**, and an ID from 0x00 to 0xFF. Define it in **include/model_ids.h**. Ensure it does not share an ID with another model that might be loaded in the same level.

In your level script file (such as **levels/bob/script.c**) or in a global script located in **levels/scripts.c**, add a LOAD_MODEL_FROM_GEO command, such as **LOAD_MODEL_FROM_GEO(MODEL_CUSTOM_COIN, custom_coin_geo)**.

===== Create behavior script =====

Open **data/behavior_data.c** in your favorite code editor. You may want to add a dedicated file, such as **data/custom_coin.c** (it is automatically found and included by the Makefile). Also add your new behavior name as a declaration in a header file, such as in **include/behavior_data.h**.

The easiest way to create your own behavior script is to copy an existing one that's most closely to what you want. Copy the related lines and rename the variable accordingly.

===== Create native code =====

If you need new native C code, create a new code file in src/game/behaviors, such as **src/game/behaviors/custom_coin.inc.c**, and include that file in **src/game/obj_behaviors.c**. You might want to copy an existing behavior code for reference. However, make sure all variables and function names are unique in the source code. For example, rename bhv_yelow_coin_loop to **bhv_custom_coin_loop**. Declare your custom functions in a suitable header file, such as in **src/game/obj_behaviors.h** or **src/game/behavior_actions.h**.

===== Add object to level (Fast64) =====

In your level inside Blender, add an Empty. Set object type to **Object**.

Set model to **Custom** and model ID to your defined ID from include/model_ids.h, such as **MODEL_CUSTOM_COIN**.

Set behavior to **Custom** and behavior name to your defined name in data/behavior_data.c, such as **bhvCustomCoin**.