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Editor to share with you the example analysis of Lod and Occlusion Culling in Unity, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

Lod and Occlusion Culling

Lod and occlusion culling.

Occlusion Culling:Occlusion Culling technology means that when an object is obscured by other objects and is invisible to the current camera, it can not be rendered. Occlusion culling does not occur automatically in the Unity engine, because in many cases objects far away from the camera are rendered first, while objects close to the camera are later rendered, overwriting previously rendered objects (this is called repeatedly rendered overdraw). Occlusion culling is different from visual vertebra culling (Frustum Culling). Visual vertebral culling only does not render objects outside the visual range of the camera, while objects obscured by other objects but still within the range of the optic vertebra will not be removed. (visual vertebral culling is still valid when occlusion culling function is used)

Occlusion culling: in our scene, if object 1 obscures another object 2 in Camera rendering, object 2 will not be rendered in Camera. Although object 2 is not rendered in Camera, it also exists throughout the game scene. In order to optimize efficiency, occlusion culling is needed here.

Lod: if an object is far away from our Camera, we naturally can't see it (or can only see a "dot"). However, this object will still render according to its vertex structure and consume performance in the scene. For optimization at this time, if it is far away from our Camera, we do not need to render it, that is, Lod.

Occlusion Culling (Occlusion culling)

Occlusion culling is implemented using Occlusion Culling (occlusion culling) components in Unity

First of all, we need to bake the objects that need to be occluded and obscured.

When baking, we need to choose different solutions for different situations between the occluded object and the obscured object. (for example, when a glass object obscures another object, we should also render the object behind the glass)

This situation is not considered here, and the baking is carried out directly.

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After the baking is complete, let's change the property of Occlusion Culling from Edit to Visualize to see the effect.

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Objects that cannot be rendered in Camera will not be rendered in the scene.

Lod

Lod function, unity built-in components will also provide us with a set of solutions. (LOD Group component)

First of all, let's create a small ball, you can see that the camera is very far away, at this time can only see a small dot. But it is still rendered in the scene.

Implement LOD optimization and add LOD Group components to it.

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Among them, LOD 0 and LOD 1 are the distance regions of Camera distance from the ball.

We can choose whether or not to render the ball at this distance in these relative distance areas.

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We add the Mesh grid information of the ball in the distance area where the ball needs to be rendered, so that the scene renders the ball within the distance from the Camera to the ball.

When we drag to the back of the distance area of LOD 2, the scene will think that the ball does not need to render the ball at such a distance from Camera, then the ball will not be rendered. (just cancel the rendering of the ball, not that enable is equal to false, so the mesh information of the ball still exists. )

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If you feel that the distance ball still needs to be rendered, you can add the ball's render to the distance area through Add. The ball will be rendered.

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If you don't want any of these distance areas, you can also edit them and create new ones.

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Run the game to observe the effect, when the ball specific to our Camera beyond the distance area of our rendering, the ball will not render. Although the ball is still in the field of vision of our Camera

The defects of the above scheme.

The above operations are all static objects, but in our actual project development, NPC,Monster, buildings and so on are generated dynamically. In this case, it certainly cannot be baked into static.

Dynamic solution. (LOD)

At this point, we use scripts to control. The core of LOD is to deactivate the MeshRender component of the ball at a long distance. We write code according to this core point.

Add a LODAndOcclusionController script to our Camera.

Complete the simple dynamic LOD function.

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Scene testing.

At this point, we can find that when the distance between the Camera and the ball is more than 5 meters, the ball will not render. It doesn't matter that the ball moves dynamically.

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Dynamic solution. (occlusion culling)

Rayray rays are used to judge.

We add Tag to Occlusion all the objects that need to be masked and culled.

And add scripts to our Camera.

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The above is all the content of the article "sample Analysis of Lod and Occlusion Culling in Unity". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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