Version: 2020.1
Optimizing Shader Load Time
Streaming Controller

Mipmap Streaming

The Mipmap Streaming system gives you control over which mipmap levels Unity loads into memory. This system reduces the total amount of memory Unity needs for Textures, because it only loads the mipmaps Unity needs to render the current CameraA component which creates an image of a particular viewpoint in your scene. The output is either drawn to the screen or captured as a texture. More info
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position in a SceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
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, instead of loading all of them by default. It trades a small amount of CPU resources to save a potentially large amount of GPU memory.

You can also use the Memory Budget to set a total memory limit for all Textures to use in a Project. The Mipmap Streaming system automatically reduces mipmap levels to stay within this budget.

You can use the Mipmap Streaming API to request specific mipmap levels for specific Textures. Unity provides sample C# code that duplicates the engine logic for mipmap selection, which you can use to override the engine logic for your own Projects. For more details, see Mipmap Streaming API.

In Unity’s Viking Village demo project, Mipmap Streaming saves 25–30% of Texture memory, depending on Camera location.

Getting started

To enable Mipmap Streaming, go to Unity’s Quality Settings (Edit > Project SettingsA broad collection of settings which allow you to configure how Physics, Audio, Networking, Graphics, Input and many other areas of your Project behave. More info
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> Quality) and enable the Texture Streaming checkbox. This reveals the settings specific to the Mipmap Streaming system. For details on each setting, see documentation on Quality Settings.

When you’ve done this, set up Mipmap Streaming on individual Textures, to allow the Mipmap Streaming system to stream each Texture’s mipmaps from the disk into memory. To do this, select the Texture you want to apply Mipmap Streaming to, navigate to the InspectorA Unity window that displays information about the currently selected GameObject, Asset or Project Settings, alowing you to inspect and edit the values. More info
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window and view the Texture Import settings. Open the Advanced settings, and enable the Streaming Mip Maps checkbox.

If you’re developing for Android, you also need to open the Build Settings and set the Compression Method to LZ4 or LZ4HC. Unity requires one of these compressionA method of storing data that reduces the amount of storage space it requires. See Texture Compression, Animation Compression, Audio Compression, Build Compression.
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methods for asynchronous Texture loading, which the Mipmap Streaming system relies upon.

Unity loads mipmaps at the highest resolution level possible while observing the Texture Memory Budget. For more specific control, or to fine-tune the Mipmap Streaming system’s automatic results, use the C# API to specify mipmap levels for each Texture. For more details, see Mipmap Streaming API.


For Mipmap Streaming, you need to assign each Texture to a Unity Renderer to allow the system to calculate the required mip level, unless a script requests manual mip levels (see documentation on Texture2D.requestedMipmapLevel). If you do not assign a Texture to a Renderer (and do not set a manually requested mip), the system cannot calculate what mip to use. This results in Unity loading the Texture with reduced mips, which look blurry when close to the Camera.

The following systems don’t use standard Renderers, so you should disable Mipmap Streaming on Textures associated with them:

  • Decal projector Textures.
  • Reflection probeA rendering component that captures a spherical view of its surroundings in all directions, rather like a camera. The captured image is then stored as a Cubemap that can be used by objects with reflective materials. More info
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    Textures. These are related to different Material properties at lower mips, so it doesn’t make sense to stream them.
  • Textures in Unity’s TerrainThe landscape in your scene. A Terrain GameObject adds a large flat plane to your scene and you can use the Terrain’s Inspector window to create a detailed landscape. More info
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    system. Unity does not support Mipmap Streaming on Terrain Textures, because the system usually blends these Textures over the whole Terrain, so they should stay on the GPU.
  • Systems which have complex Texture blending in the ShaderA small script that contains the mathematical calculations and algorithms for calculating the Color of each pixel rendered, based on the lighting input and the Material configuration. More info
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When Unity renders a streamed Texture directly with an API (such as Graphics.DrawMeshNow) the system has no renderer bounds information to calculate the mip level, so you need to set the Texture mip level explicitly (or disable Mipmap Streaming on this Texture). See documentation on Texture2D.requestedMipmapLevel for more details.

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Optimizing Shader Load Time
Streaming Controller