Explain the camera in unity and its application

Preface

Unity in , Show players the wonderful game world through the camera . Developers can fix the player's perspective through the camera , Render a specific picture to present to the player . This paper introduces Camera Relevant parameters of components and some application examples and misunderstandings of how to use the camera .

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 2022.4.3

Video Explanation ：
Detailed explanation Unity The video camera _BiLiBiLi

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One 、 Introduction to camera components and parameters

When you create a scene ,Unity It will automatically create one Main Camera, If you delete it , Then your world will be dark . We can do it in Hierarchy Window right , Create a Camera, Then you will find , Your world is bright again .

When we build Camera, Then you will find , It mounts three components , Namely Transform、Camera and Audio Listener, among Transform It is owned by every game object ,Camera and Audio Listener The ears and eyes of this camera . Now let's introduce in detail about Camera Component related parameters .

Create a new one Camera, Automatically add these three components .

1.ClearFlags: Clear the mark （ background ）

When the camera renders the view , Will cache color and depth information , The part of the drawn image that is not drawn is blank , By default, the color of the sky box will be displayed .

• Sky Box： Use the sky box to fill the blank space , Render settings are used by default [Window-Rendering-Lighting Settings] Sky box in , If the rendering settings do not set the sky box , Will use the background color .

• Solid Color： Fill the blank with the camera background color
• Depth Only： No fill

It's easy to understand , Parts other than painting are filled with default black , If there are other cameras at this time （Depth Lower than current ）, Fill in other camera pictures .

• Don’t Clear: Do not clear the color and depth cache .( Not much use here , No explanation. , Anyway, I don't understand )

Background: The background color （ When ClearFlags choice Solid Color when , This option works ）

2.Culling Mask: Select a render layer

Render the object of the specified layer by selecting the layer ,Unity Each object in is assigned a layer , The default is “Default” layer

I put the cylinder and cube on the layer “Camera Culling Mask”, Through the demonstration, the reader should be able to understand that this parameter does
adopt Camera.cullingMask To modify this value in the code ,Int type , The default value is 0

3.Projection: Projection mode （ perspective （ Default ） and orthogonal ）

• FOV Axis： Visual field axis
  Vertical： Vertical axis , After this item is set , adjustment FieldOfView It will change the opening and closing angle of the camera
  Horizontal： Horizontal axis , After this item is set , adjustment FieldOfView It will change the opening and closing angle of the camera
• Field Of View: Range of view （ The camera's field of view is stretched ）, The bigger the perspective , The larger the field of vision , At the same time, the shorter the focal length

Code can be passed through Camera.fieldOfView Class variable to modify this value , Unit degree , When the camera is in orthographic mode , This parameter is ignored

• Physical Camera: later , I haven't figured it out yet
• Size（ Orthographic mode options ）： Camera viewport size , Half of the area drawn by the camera in the vertical direction of the screen .

4.Clipping Planes: Clipping plane

seeing the name of a thing one thinks of its function ,Near and Far Specifies the region range of its clipping , If it is not in this range, it will not be rendered , It can save the amount of calculation , How many settings are appropriate , See the demand .

In the code, you can use Camera.farClipPlane and Camera.nearClipPlane Class variable to modify this value

5.Viewport Rect: View rectangle （ Camera position width and height ）

Here are four values , among X and Y Represents the origin of the camera , Generally no change .
W and H Represents the width and height of the camera , Default 1 It is full screen , The screen coordinate system is used here to calculate , Readers who don't understand can go to my column to check about Unity Explanation of coordinate system in （ expect 22.4.10 Will write it out ）,

It can be modified by W and H The effect of superimposing the views of two cameras . How to apply , Let's talk about it later

Here I set up two cameras , The main camera is rendered first , Then the camera in the lower left corner is rendered , And set the camera ClearFlags by Depth Only, This will not render superfluous parts , The effect shown in the above figure is achieved .

6.Depth: depth （ Camera rendering order ）

Used to control the camera rendering order , Generally, those with small values will be rendered first , Larger values will be superimposed on the previous camera , The last example used , The order of cameras in the lower left corner is ：0, The order of main background cameras is ：-1, Therefore, it can ensure that the main background camera is rendered first , Then it is superimposed by the camera in the lower left corner .

adopt Camera.depth Class variable to modify this value in the code

7.Occlusion Culling： Shielding elimination switch

Checking this option will help improve game performance , For example, objects outside the scope of the camera , Will not be rendered

It should be noted that , Objects in the scene need to be pre calculated , And it is a static object , When checked Unity Can quickly and real-time judge whether the object is within the range of the camera .

8. Other properties , Temporarily unavailable , I won't go into that

In fact, I didn't understand , Add it after I understand

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Two 、 Example application of camera

With the above parameters , Readers should basically understand Unity The camera in , Let's consolidate it with a few simple cases .

1. Control camera scene roaming

demand ： adopt WASD To move the camera back and forth, left and right , adopt QE It can be lifted and lowered , Hold down Shift Can speed up .
You can zoom the view through the mouse wheel , Press the right mouse button and move , You can rotate the camera

The dynamic diagram of the demonstration is as follows ：

In fact, the whole part of the code does not apply too many camera related parameters , The example is simple . But the code is smelly and long , For novice reference , No quality . And this code has Bug, The rotation is not locked Z Axis , This will cause the camera to rotate around the center for no reason .
High EQ ： Please find out Bug And repair
Low EQ ： I'm too lazy to write

    public Camera camera_;
    //  Camera movement speed and rotation sensitivity 
    public float mouseSenstivity = 100;
    public float speed = 5;
    void Update()
    {
        // The keyboard controls the camera movement 
        Move_Update();

        // The mouse wheel controls the scene zoom 
        MousewheelZoom_Update();

        // Right click to control the scene rotation 
        MousergihtRot_Update();
    }
    private void Move_Update()
    {
        if (Input.GetKey(KeyCode.W))
        {
            camera_.transform.Translate(Vector3.forward * Time.deltaTime * speed);
        }
        if (Input.GetKey(KeyCode.S))
        {
            camera_.transform.Translate(Vector3.back * Time.deltaTime * speed);
        }
        if (Input.GetKey(KeyCode.A))
        {
            camera_.transform.Translate(Vector3.left * Time.deltaTime * speed);
        }
        if (Input.GetKey(KeyCode.D))
        {
            camera_.transform.Translate(Vector3.right * Time.deltaTime * speed);
        }
        if (Input.GetKey(KeyCode.Q))
        {
            camera_.transform.Translate(Vector3.up * Time.deltaTime * speed);
        }
        if (Input.GetKey(KeyCode.E))
        {
            camera_.transform.Translate(Vector3.down * Time.deltaTime * speed);
        }

    }
    private void MousewheelZoom_Update()
    {
        if (Input.GetAxis("Mouse ScrollWheel") < 0)
        {
            camera_.fieldOfView += 2;
        }
        if (Input.GetAxis("Mouse ScrollWheel") > 0)
        {
            camera_.fieldOfView -= 2;
        }
    }
    private void MousergihtRot_Update()
    {
        if (Input.GetMouseButton(1))
        {
            // X The shaft controls up and down rotation ,Y The axis controls the left and right rotation 
            float mouseX = Input.GetAxis("Mouse X") * Time.deltaTime * mouseSenstivity;
            float mouseY = Input.GetAxis("Mouse Y") * Time.deltaTime * mouseSenstivity;
            
            //  Pay attention here because X The axis controls up and down ,Y The axis controls the left and right 
            //  and mouseX The left and right values of the screen are returned , All of them switched 
            //  Again because mouseY Downward is negative , And the camera Y When the axis is downward, it is positive , On the other hand mouseY A negation is made .
            //  If you can't understand it here , I recommend reading the first blog post in resources , Sum up Unity Related movement control methods .
            camera_.transform.Rotate(new Vector3((0f - mouseY), mouseX, 0));
        }
    }

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3、 ... and 、 Summary and references

1. summary

There's nothing to summarize , Mainly remember the functions of several parameters of the camera .

2. Reference material

[1]. Dream of a young man . Detailed explanation Unity Mobile control implementation
[2]. Dream of a young man . Detailed explanation Unity Several mobile ways of
[3]. Xueting .unity in camera Camera control details
[4]. Lingbao'er .Unity Physical Camera in Focal Length and Field of View Relationship
[5].syddf_shadow. Sky box (SkyBox) The implementation principle and details of
[6]. Game bulls .[ Manniu tutorial ] Unity3D elementary analysis －Camera（ The camera ）
[7]. Xingxiaopeng .unity movie camera depth Pattern _Unity3d Camera details