Explain the imported 3D model in unity

Preface

A three-dimensional model can represent any object that exists in the real world , Naturally, it can also represent any object existing in the game world , Like the ground , Mountains and rivers , Flowers and trees , Architecture , figure , All need to use three-dimensional models to represent . Generally, we use some modeling software to build the model needed in the game , Then import to Unity Use in , This article will introduce , A whole 3D Model making and importing process and problems needing attention .

Front row reminders ： This article only represents personal views , For exchange and learning , If you have different opinions, please comment , The author must study hard , Day day up .
When reading this article , If there is something you don't understand , It is recommended to watch the references listed in this article for comparison .

Unity edition [2019.4.10f1] Dream small day young & Prohibited reproduced

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One 、3D Introduction to the model

3D models are not only used in the game industry , It is also widely used in industrial design 、 Architectural design 、 3D animation and other fields , It is not attached to the existence of the game industry , But an independent system .

1. What is a model

Many people come into contact for the first time 3D The model will encounter many strange nouns , Such as grid , texture , texture of material , Mapping, etc . Generally speaking ：
The mesh is the shape of the model , A map is a picture posted to the surface of an object , Texture is the texture on the surface of an object , Material is to simulate the interaction of objects with light
texture of material = Mapping + texture
Model = grid + texture of material
This is not rigorous enough , About mapping 、 texture of material 、 The concepts of texture , If you want to talk about it in detail, you should open another article . Dig a hole , Get ready 22 year 5 Issued at the end of the month .

2.Unity Supported model formats

Unity Support many general formats and export formats of mainstream modeling software , Let me briefly list a table .

Originally, I wrote a lot , Supported format , Supported software , But then I thought about a lot of miscellaneous formats , I've never heard of , Novices will not touch , So remember FBX Just format it , Most common modeling software supports import and Export , And support material animation bones , you are here 3Dmax Import the finished animation into Unity It can be used directly , This is the most commonly used format .

3. Common modeling software

The table above lists four , Let me briefly introduce these four .

• 3D Max: Well known but bloated software that has to be used with extremely slow startup speed .

• C4D: Commonly used in film and television 、 E-commerce design . Others also dabble .

• Blender: Open source ！ The universal ！ God forever ！

• Maya: Mainly used for animation , Animation is the top in the industry ！

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Two 、Blender|FBX Import to Unity And use

1. Make a model

Blender The interface is as above , Version is 3.1.2

If I have a need now , I need to make a LowPlay Style games , Need one LowPlay The tree of , Now? > We have made such a tree . The production process is omitted , give the result as follows

Now I give this tree a green material , The trunk and leaf materials are named trunk,leaf

Then merge the model , And set the center point of the model to the bottom of the model
（ It would be troublesome not to merge , For example, somehow the trunk was moved , The treetops are still in place , It's better to merge into a whole . As for when to merge and when not to merge , Can refer to the real world , For example, when you pick up the stool, you pick it up as a whole , Put it in the model , Can be merged into a whole . For example, the pots and pans on the table and the table itself , Can be picked up independently , Then don't merge into a whole . This mainly depends on the game demand ）

2. Export the model and set the parameters correctly

Then click file -> export ->FBX, The following window will pop out

You need to pay attention to the several options specially marked in the above figure .

• The zoom : Represents how many times your model is scaled and then exported , If you generally model according to the proportion of the real world , Import to Unity There will be no distortion , So the default is 1 that will do .
• Apply zoom ： By default
• Forward ： This particular attention , If you import to Unity in , It needs to be changed to ,Z forward
• Up ： Import to Unity Medium needs to be changed to Y Up
  If you need to import to other game engines or modeling software , You need to understand the world coordinate system of the game engine . such as Unity The coordinate system of is left-handed ,Z front Y On X Right . So we need to change the coordinate direction .

Other settings can be set by default .

3. Import to Unity And use

When you click on " export FBX" After button , You have derived a FBX file , Then drag the file directly into Assets You can complete the import ( Or from the menu item Assets->Import New Asset Import )

The structure of the imported model file is as follows , There are two shaders , A grid , take tree Drag the whole into the scene , You can use

At this time, you can clearly see the XYZ The axis and world coordinates are opposite , If it is not set just now , Then this tree must appear in a very strange way .

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3、 ... and 、3DMax|FBX Import to Unity And use

Reuse 3DMax Demonstrate with the same steps

1. Make and export models , And setting parameters

3DMax2019 The software interface is as follows , The model is also ready , as follows

When you export , The window will pop up , And the above blender equally , You just need to change the axis conversion in the advanced options . however 3Dmax The default is Y Axis up , So you don't need to make any changes at all , You can export and use

2. Import to Unity And use

Import Unity Drag and drop , Then drag it into the scene , as follows . Oh , Forgot to give the material , But it's not a big problem .

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Four 、 Common problems and precautions

About 3Dm The model is imported into Unity in , You only need to pay attention to the following points ：

• Whether the current format supports exporting materials in your model , Animation , bones , For example, you make a tree with materials , It is derived that OBJ Format , Then import to Unity, Then you wonder , Where is my material ？ Use FBX This problem will not arise .
• When exporting settings , Whether the current axis is Z front ,Y On ,Z front Y On is Unity The world coordinate system of , You have to convert to this coordinate system to export , otherwise , Put it in Unity Scene , It may be disoriented .
• When exporting settings , Pay attention to whether your model size is modeled according to the real world , If not , Remember to resize .
• Before export , Remember to check whether the center point of your model is in the center or at the bottom of the center .

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5、 ... and 、 Summary and references

1. summary

nothing

2. Reference material

https://zhuanlan.zhihu.com/p/163380009
https://www.zhihu.com/question/25745472?ivk_sa=1024320u
http://news.sohu.com/a/503415464_121143937