Unity 2D Game Development Part-1

Unity 2D Game Development Part-1

Importing 3D Models and Animations

In this chapter, we prepare the assets to build up our game prototype, starting with the process of exporting 3D models from Maya, our 3D editor of choice, into Unity. We also take care of correctly setting up the imported models and animations in Unity Inspector once they get imported.

In this chapter, we will cover the following recipes:

·         ffSetting up a scene in Maya

·         ffUsing groups to rotate FBX files

·         ffExporting FBX files from Maya

·         ffConfiguring imported FBX files in Unity

·         ffExporting animations

·         ffConfiguring imported animations in Unity Inspector

Introduction

When building up a game, we usually start by importing the graphics assets to actually build up and prototype the gameplay.

In this specific case, we decided to begin with 3D models. Before importing the models, you should take care of bringing in the textures. Feel free to switch between Chapter 1 and Chapter 2, 2D Assets for Unity, which focuses on textures and materials. A cookbook is specifically designed to leave the readers free to access the contents in whichever order they prefer. Importing 3D Models and Animations

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We assume that you have the assets to test the operations explained throughout this book; in case you don't, you can download the contents available on Packt Publishing website.

When importing models from a 3D software into Unity, there are several settings to be defined: scales, source materials and textures, rigging and animations, and many others. We will discuss the most important setting soon.

For the importing process to be fully successful, it is also important that the scene in the 3D editor is properly set. When modeling stuff with a 3D editor for a 3D engine, it is important that scales, lights (if available), and cameras match between the scenes, or your models won't fit the game levels properly.

For the recipes of this chapter, we decided to pick Maya as our reference 3D editor. We do not mean that Maya is the best software, but there are plenty of reasons for this choice. Native Maya files are supported by Unity, and the LT version of Maya allows you to perform "one-click-exporting" of Maya scenes directly into Unity (http://videos. autodesk.com/zencoder/content/dam/autodesk/www/products/ autodesk-maya-lt/video/send-to-unity-fbx-export-video-1280x720.mp4).

Maya is also an industry standard for 3D artists, and it is supported by both Windows and OS X (while 3D Studio Max, for example, isn't). You can check out 3D forums to delve into the differences between 3D software. The following is a list of very popular forums to begin with:

·         ffhttp://forums.cgsociety.org/

·         ffhttp://www.polycount.com/forum/

·         ffhttp://www.gameartisans.org/forums/forum.php

Setting up a scene in Maya

The first point to keep in mind when setting up a scene in Maya is that the standard unit in Maya is 1 cm, while the standard unit in Unity is 1 m So, whenever you export an FBX file from Maya into Unity, Unity scales it down to 0.01 percent of its original size.

Another very relevant point is that Maya and Unity are affected by strange kinds of idiosyncrasies that put them on opposing sides, with regard to what left or right and front or bottom mean. This is not something that only happens between Maya and Unity. Many 3D software disagree about the concepts of right and up. To get an idea, have a look at the following image, taken from Unity's forum:

As you can see, the red arrow, representing the left-right axis in the 3D world, may point to the left or right on different software or file formats, and the green and blue axes may switch to alternatively point to the forward or upward directions.

With Maya and Unity, what happens is that the front in Maya is the back in Unity. So you model the front of a character in Maya, and when you import it into Unity, it shows its back.

How do we deal with this? There's more than one option available, and turning the camera by 180 degrees in Unity is not the only one. We will show you how to deal with this problem but, before this, we need to learn how to actually export an FBX file from Maya and add it to a Unity scene, which is what we will do in the first recipe of this chapter.

Getting ready

For this recipe, we need a Maya scene with a 3D model, any model with at least one material applied to it. A textured model is provided with the contents of this book.

How to do it...

In this recipe, we will show you how a model is exported from Maya using the default FBX exporter panel and how the FBX file will get imported in Unity.

1.       Open your model in Maya. 

1.       Open the outliner panel, and from the hierarchy, select the root node of your model. Remember that it is good practice to name the root node with a meaningful name, such as root. It can turn out to be useful, for example, when managing the exporting process through scripts (as shown later).

2.       Now, in the top menu window, navigate to File | Export Selection. The Maya exporter panel will open, as shown in the following screenshot. Don't bother with the panel on the right-hand side with the actual settings; we will get back to it in a while. 

1.       Be sure that FBX export is selected from the drop-down menu at the bottom.

2.       Put a name you like in the File name field.

3.       Click on Export Selection to save the file in your destination folder.

4.       Now open Unity and, in the project panel, right-click and select Import New Asset…. from the menu: 

1.       Select your saved FBX file from the Explorer window that opens and click on Import.

2.       Alternatively, you could have directly exported the FBX file from Maya into the Assets/Models directory of your Unity project.

1.       Now select the FBX file from the project panel and drag it onto the scene. The following screenshot shows what happens in Unity:

How it works...

The operation of exporting FBX files from Maya is simple: select the actual root node in the hierarchy and click on the Export button. But, as you can see, unless we use some precautions, the result of importing an FBX file from Maya is that the model is flipped by 180 degrees on the the y axis in Unity. This happens because the blue arrow that represents the z axis in Maya points in the opposite direction in Unity. As a consequence, the model shows its back to Unity's camera.

As we write, there are rumors that this issue is going to be solved in forthcoming Unity versions. For now, we will provide custom solutions we have used ourselves.

Using groups to rotate FBX files

An efficient solution to dealing with the discrepancy between Maya and Unity is to act on Maya's side and rotate the model on its y axis there. Though, as we write, this problem is going to be solved soon by Maya LT, we offer a solution here that prevents the imported FBX file from acting strangely once they are turned into prefabs in Unity. The idea is to use the so-called "groups" to apply the transformations required and yet get a clean hierarchy for the prefab to appear in Unity. Let's see how to do it.

It was first published,www.it-ebooks.info and theit-mela.blogspot.com