Android 2D Texture Overrides

このページでは、特に Android に関して、テクスチャ オーバライド の詳細を説明しています。テクスチャオーバーライドの一般的な説明は、こちらを参照してください。

The information contained on this page assumes the reader has working knowledge of DXT and ETC Texture compression, OpenGL ES, and Android development.

テクスチャ圧縮と OpenGL ES に関する詳細な情報は以下のページを参照してください。

• DXT Texture compression
• ETC (Ericsson Texture Compression)
• Lossy compression
• OpenGL ES

If your app is installed on a device that doesn’t support the Texture compression format it uses, Unity decompresses the Textures to RGBA 32 and store them in the device’s memory, along with the compressed Textures, while the app is running. This leads to increased loading times and higher memory usage, because Unity must decompress the Textures and store two versions of the Textures used (compressed and uncompressed). This can also have a large impact on rendering performance, especially on older, slower devices.

Use ETC2 compression unless your app targets specific hardware like the Nvidia Tegra. ETC2 supports Textures with and without an alpha channel, and all OpenGL ES 3 devices support it. To avoid software decompression, follow these steps:

1. Open the Android Player settings (menu: Edit > Project Settings > Player Settings).
2. In the Other Settings section, remove OpenGL ES 2 from the Graphics APIs list. This sets the minimum graphics API to OpenGL ES 3.
3. In the Other Settings section, set the Minimum API Level to Android 4.4 ‘KitKat’ (API level 19).

To target OpenGL ES 2 and OpenGL ES 3 devices, you can create and publish two different APKs. Follow these steps:

1. Build an APK that targets OpenGL ES 3, using the Player settings in the screenshot above.
2. Build a separate APK that targets OpenGL ES 2. To do this, remove OpenGL ES 3 and Vulkan from the Graphics APIs section of the Player settings.
3. Publish both of these APKs to the Google Play Store. When a user downloads your app, the Google Play Store automatically installs the most relevant APK for their device.

複数の APK ファイルの公開に関する詳細は、以下の Android Developer ドキュメントを参照してください。

• 複数 APK サポート
• Google Play でのフィルタ

OpenGL ES 2 をターゲットとする APK を構築するときは、ETC1 テクスチャ圧縮を使用します。

The Texture compression format for OpenGL ES2-targeted APKs can be ETC1. Unity can use ETC1 for Textures with Alpha, provided they are placed on a sprite atlas (by specifying the packing tag) and the build is for Android. You can opt in for this by setting the Compress using ETC1 checkbox for the Texture. Unity then splits the resulting atlas into two Textures, each without alpha, and then combines them in the final parts of the render pipeline.

If you must store an alpha channel in a Texture, all hardware vendors support the RGBA 16 bit compression format.

• 2017–09–18 Page amended

• Unity 2017.1 のアップデート機能

• Crunch 圧縮形式は Unity 2017.3 で更新NewIn20173