Importing Paint 3D Models: A Guide For Unity Developers

Unity is a game engine and software development platform used for creating video games and other experiences in real-time 3D. Paint 3D is a built-in Windows 10 app that allows users to create and paint 3D models. While Paint 3D is a simple and accessible modelling tool, its models cannot be directly imported into Unity. One way to circumvent this issue is to import the models into Blender or 3ds Max for cleanup and retopology before transferring them to Unity. Alternatively, you can export your model from Paint 3D as a .GLB file and open it in 3D Builder.

Save your Paint 3D model as an FBX file

To move a Paint 3D model to Unity, you need to save your Paint 3D model as an FBX file. This file format is supported by Unity and allows for the transfer of 3D models between different software programs. Here's a step-by-step guide on how to do it:

Start by opening your Paint 3D project and selecting the model you want to export. In the menu bar, click on the "File" tab and then select "Save As". In the "Save as type" dropdown menu, you should see an option for .FBX or "FBX File". Choose this option and then name and save your file.

Now that you have your FBX file, you can open it in Unity. Launch Unity and create a new project or open an existing one. In the Unity interface, navigate to the "Assets" folder. This is where all your project's assets, including 3D models, are stored. Drag and drop your FBX file into the "Assets" folder. Alternatively, you can go to the "Assets" menu and choose "Import New Asset", locate your FBX file, and import it this way.

Once the FBX file is imported into Unity, you should be able to see it in the "Project" window. You can now use this model in your Unity project. Right-click on the model in the "Project" window and select "Inspect" to view its properties and components. From here, you can make any necessary adjustments to the model's materials, textures, or transformations.

While this method should work for transferring your Paint 3D models to Unity, some users have reported issues with the models appearing grey in Unity. If you encounter this issue, there might be additional steps or workarounds needed to fully integrate your Paint 3D models into the Unity environment.

Import the FBX file into Unity

Unity's primary support for model files is the FBX format. You can import FBX files directly to and from Unity without specifying filenames, selecting objects, or setting importer or exporter settings.

To import an FBX file into Unity, first create an export set through File > Unity > Import or File > Unity > Create Export Set. You can then edit the export options on the set by selecting it and modifying the Unity attributes in the Extra Attributes section of the Attribute Editor.

Importing an FBX model automatically configures the plug-in for export. The plug-in will remember your Unity Project, the export filename, and which objects to export. Select Import to open a file browser directly in your current Unity Project.

If your FBX file contains materials and textures, you can define how you want to deal with them. Select a model file from the Project window, then select the Materials tab in the Inspector. Use the Material Creation Mode drop-down menu to choose how you want to import the materials from the FBX file.

If your file contains a mesh, drag the file into the Scene view.

Open the model in Unity, which should appear as a default grey colour

To open your Paint 3D model in Unity, you must first save your model in Paint 3D as an FBX file. Next, open the file in Unity. The model should appear in a default grey colour. This is normal and expected behaviour.

If you are having trouble with the texture of your model, try the following steps. First, export your model from Paint 3D as a GLB file. Then, open the GLB file in 3D Builder. You can also try importing your model into Blender or 3ds Max for clean-up or retopology before importing it into Unity.

If you are still having issues, it may be helpful to know that some users have reported that Paint 3D models cannot be put into Unity. One user reported that their model appeared as a default grey cube when they tried to import it into Unity.

Create a new material in Unity and apply it to the model

To create a new material in Unity, you must first understand the relationship between materials and shaders. Shaders are small scripts that contain mathematical calculations and algorithms for determining the colour of each rendered pixel based on lighting. The standard shader, for instance, performs complex and realistic lighting calculations. Each shader has a number of properties that can be assigned values by a material using that shader. These properties can be numbers, colour definitions, or textures.

To create a new material, you can start by assigning it the Standard Shader, which is the default option for new materials, with all map properties initially empty. From there, you can tweak the material's properties in the Inspector, a Unity window that provides information about the currently selected GameObject, Asset, or Project Settings.

To apply the new material to an object, simply drag it from the Project View to any object in the Scene or Hierarchy. The Scene is where you design and build your game environments, obstacles, and decorations, while the Hierarchy displays the objects in your Scene.

It's important to note that materials are used by Renderer components attached to Game Objects to render each object's mesh. Meshes are the primary graphics primitive in Unity, and they make up a large part of your 3D worlds. You can have multiple materials referencing the same textures, and this is often desirable.

Additionally, when working with textures, you may encounter texture atlases, where different parts of the texture image are mapped to different parts of the model. This mapping, known as "UV mapping," is done by a 3D artist in an external 3D application.

Use Blender or 3DS Max to clean up the model or do some retopology

Blender is a free and powerful 3D tool that can be used to clean up a model or perform retopology. To clean up a 3D scan using Blender, you can follow these steps:

• Import the scanned model into Blender. Change your viewport to "Orthographic View" and rotate the model to orient it correctly.
• Use the Sculpt mode and the Grab brush to fix any issues with the scanned model, such as holes in the mesh or parts that didn't scan well.
• Add a Subdivision Modifier to your mesh to smooth out the details and improve the overall shape.
• Apply a Shrinkwrap Modifier to your mesh, using the scanned mesh as the target. This will help to ensure that the cleaned-up model maintains the original shape of the scan.

For more complex retopology tasks, Blender offers a range of tools. Manual retopology in Blender can be done using tools like Bsurface or Poly Build, which allow artists to draw new polygons directly onto the model's surface, ensuring optimal topology for animation or deformation. Blender also offers automatic retopology tools like Quad Remesher, which can quickly generate a clean quad-based mesh. This can be combined with RetopoFlow for further refinement.

While this answer primarily focuses on Blender, 3DS Max also offers retopology tools that can be used to clean up models. The Max 2022 Retopology modifier, along with the subdivide modifier, can help clean up bad topology and imported meshes. Additionally, 3DS Max's remesh feature can be used for cleaning up models, similar to Blender's Remesh modifier.

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