Today, we will learn about sprites, sprite atlas, and sprite animations used in Unity 2D game development. A draw call is when the CPU requests the GPU to draw an image, and the lower the draw call value, the lighter the game is. However, exceeding a certain number depending on the device can lead to frame rate drops. Batching is a concept that includes draw calls. From Unity 5.0, rendering information is represented based on batching instead of draw calls. Batching can be checked in the stats of the Unity Editor Game View, where it comprehensively calculates and displays information such as mesh, material, shader, and draw calls. In conclusion, having a low number of batches is preferable. While this video does not delve into detailed explanations as it is not specifically about game optimization, one way to reduce batches is by using sprite atlases. The technique of sprite atlas is.

Unity provides a Sprite Atlas, which allows you to gather multiple image files into one image file and use only the necessary parts. The reason for using a Sprite Atlas is that in 2D games, such as backgrounds or character representations, each sprite causes a draw call every time it is rendered. For example, if there are 100 objects in a game using different sprites like characters, enemies, items, each requiring a separate draw call, the draw calls would be 100 when they appear simultaneously in the game. However, if there are 100 objects using the same sprite, the draw calls would only be 1. By using a Sprite Atlas to combine different sprites into one texture and using them, even if you create 100 objects with different sprites, the draw calls would still be 1. Therefore, although you may think that bundling all image assets in our game into one sprite could keep the draw calls always at 1 in 2D game development, it is because they are bundled together that.

You need to get all the information of the sprite atlas file where even using just one image among many registered images will be bundled together. As the scale of the game increases, it would be very reckless to bundle all image information of one atlas. It is better to bundle related items that are commonly used together on one screen or used for one object. Include the resource files to be used as examples in the project. When you first create a scene, only the main camera is placed, and there are no objects to display on the screen, so the value of the order in the layer is 0. Create a 2D square object and change the name to Player Black. If you register the Player Black texture in the sprite renderer component, you can confirm that the value of the order in the layer becomes 1 because the Player Black image is displayed on the screen. Press Ctrl+D to control the Player Black object.

Clone them, change the name to Player Life UI, and register the Player Life UI texture on the sprite renderer component. You can see that the value of the two arranged sprites, like Player Black Player Life UI, has become 2 on the screen. Let's clone these objects with Ctrl + D to increase the number of objects. Even though the number of objects increases and more images are displayed on the screen, the sprite used for the objects is still Player Black Player Life UI, and the value of the two arranged sprites remains 2. In other words, no matter how many objects are added, the value remains 2 depending on the number of sprites currently used on the screen. Let's display all the various texture assets in the project view on the screen, increasing the value of the arrangement according to the number of texture assets displayed on the screen.

We can check and adjust the batch number using a sprite atlas provided in Unity. Let's create a sprite atlas asset. Set the type to Master with Allow Location, Tight Packing as true, and padding as 4, keeping the default settings. Register the texture ss to be grouped in the object 4 packing list. Let's register all the texture assets currently being used on the screen. Once all texture assets are registered, press the Pack Preview button to complete the setup. You can see that they are grouped into one sprite atlas. When you run the game, you can see that the previous batch value of 14 has changed to 1. Various information about the texture assets output by the game will be displayed in the Inspector view. First, the texture type should be set according to the intended use of the texture. The most commonly used texture type is 2D Sprite when applying textures for 2D sprite objects or UI.

There are two default settings when applying to the material of a 3D object. Also, the options parameters that can be set depending on the texture type will change. Since the current video is about the basics of 2D, let's take a look at the parameters of Sprite 2D & UI mainly used in 2D. The Sprite Mode can be set when the texture type is Sprite 2D & UI. It allows single developers to split images into various shapes as desired, using external images as they are. When the Sprite Editor button is pressed, you can open the Sprite Editor view to edit the image. Basically, you can modify information such as the center point of the image's boundary and split the image into polygon shapes to create multiple various shape images. You can also perform tasks such as modifying the size and number of splits for polygon-shaped images. When the Sprite Mode is multiple, the method of splitting the image into irregular sizes is

Drag the empty space to create a new partition. When dividing based on a certain rule, you can set the automatic division cell size as it appears in the Slice menu and set the number of division cells. You can use the grid division method. The reason for dividing one image is that all images used in the game are set in pot units in memory. For example, a 30 by 30 size image is stored in a 32 by 32 memory. Naturally, a 32 by 32 size image will be stored in a 32 by 32 memory. Then, what about a 33 by 33 size image? It falls short by 1 to fit in a 32 by 32 memory, so it will be stored in a 64 by 64 memory, and the remaining space will be discarded. It would be ideal to create all images used in the game in pot units, but it is realistically impossible. Therefore, various actions and animations of a character are stored in one image, as shown in the picture.

You can use the sprite mode when it's a polygon, you can convert the image asset to the desired polygon shape. Click the Sprite Editor button, open the Sprite Editor view, and change the size values ​​to Change Shape. Press the Apply button to save it. When you return to the Unity Editor, you can use the original heart-shaped image and the image converted to a triangle shape. The Pixel Per Unit sets how many pixels in the game world equal 1 unit transform scale. For example, if the Pixel Per Unit is 128 and the size of the original image is 256 by 256, when the transform scale is 1, it will appear twice as large as the default shape objects provided by Unity. To make the game look more dynamic, instead of showing one image, the image should continuously change according to the action. This is called animation, and 2D objects have a Sprite Renderer.

It is about periodically changing the images of components. In the past, I used to write code directly to change the images periodically, but currently, Unity provides this functionality. In a 2D game, for an object to play an animation, Animator component, Animator Controller asset, and Animation asset are required. The Animator component registers with the Animator Controller asset, which controls the playback and replacement of animations for game objects based on the settings in the Animator Controller asset. The Animator Controller asset bundles animations that an object can have and manages them as a file. You can create an asset in the project view by selecting the Animator Controller menu from the Create menu and open the Animator view to configure it. The Animator view is where you edit the contents of the Animator Controller asset, register animations for objects to play, and

You can set the relationship between animations. Basically, all animator controller assets have new states of animation state entry and exit. You can register various animations that you want to play, such as idle, move, attack, etc. The first state following the entry in the entry is indicated in orange and is the default state that is executed first when the object is in a state where animation playback is possible. The states other than the default state can be played when specific conditions we set are satisfied using state transitions with state precedence. Specific conditions for setting state transitions are variables declared in parameters. These variables are placed in the setting of state transitions and can be accessed and modified using scripts. An animation asset is a file that stores a single animation movement, and in 2D, you can create assets in the project view animation menu and open the animation view to configure them. The animation view is for animations.

As a view for editing content, you can configure a single animation behavior. You can access all the components that the current game object has, including movement, rotation, size, and color, not just images. You can select the animation clip that the current game object has or create a new clip. You can also set the animation playback speed to a sample rate. In the property space, you add the component parameters you want to animate and set the values for the parameters. Events are used when you want to call a method during animation playback. You can place an event icon at the desired frame position and set the method by selecting the event icon.

2022.2 유니티 2D 기초 강의 [6] - 2D 이미지 출력과 애니메이션 재생

2022.2 유니티 2D 기초 강의 [6] - 2D 이미지 출력과 애니메이션 재생