关于Unity中Texture压缩问题
2020-05-06 14:45阅读：
对于压缩格式分析如下
1、Android系列
ETC格式：仅支持OpenGL ES 2.0
GPUs
ETC2格式：支持OpenGL
ES 3.0
DXT1和DXT5格式：仅支持Android (Nvidia Tegra and Intel Bay
Trail)
ASTC格式：仅支持Android (PowerVR
6XT, Mali T600 series, Adreno 400 series, Tegra K1)
PVRTC格式：仅支持Android (PowerVR)
ATC格式：Android
(Qualcomm - Adreno)
2、高通系列：
可选择专用ATC格式
根据类型选择ETC格式和ETC2格式
同时Adreno 400
series可以选择ASTC格式
3、Mali系列：
Mali T600
series可以选择ASTC格式
一般通用选择ETC2格式或根据需求选择ETC格式
官方文档如下
Texture compression formats for platform-specific
overrides
While Unity supports many common image formats as source files for
importing your
Textures
(such as JPG, PNG, PSD and TGA),
these formats are not used during realtime
rendering
by 3D graphics hardware such as a
graphics card or mobile device. 3D graphics hardware requires
Textures to be compressed in specialized formats which are
optimised for fast Texture sampling. The various different
platforms and devices available each have their own different
proprietary formats.
By default, the Unity Editor automatically converts Textures to the
most appropriate format to match the build target you have
selected. Only the converted Textures are included in your build;
your source
Asset
files are left in their original
format, in your project’s
Assets folder.
However, on most platforms there are a number of different
supported Texture
compression formats to
choose from. Unity has certain default formats set up for each
platform, but in some situations you may want to override the
default and pick a different
compression
format for some of your Textures (for example, if you are
using a Texture as a mask, with only one channel, you might choose
to use the BC4 format to save space while preserving
quality).
To apply custom settings for each platform, use the
Texture
Importer to set default options, then use the
Platform-specific overrides panel to
override those defaults for specific platforms.
Default internal Texture representation per
platform The following table shows the default formats used for
each platform.
| Platform |
Color model |
None |
Normal quality (Default) |
High quality |
Low quality (higher performance) |
Windows, Linux, macOS,
PS4
, XBox
One
|
RGB |
RGB 24 bit |
RGB Compressed DXT1 |
RGB(A) Compressed BC7 |
RGB Compressed DXT1 |
|
RGBA |
RGBA 32 bit |
RGBA Compressed DXT5 |
RGB(A) Compressed BC7 |
RGBA Compressed DXT5 |
|
HDR
|
RGBA Half |
RGB Compressed BC6H |
RGB Compressed BC6H |
RGB Compressed BC6H |
WebGL
|
RGB |
RGB 24 bit |
RGB Compressed DXT1 |
RGB Compressed DXT1 |
RGB Compressed DXT1 |
|
RGBA |
RGBA 32 bit |
RGBA Compressed DXT5 |
RGBA Compressed DXT5 |
RGBA Compressed DXT5 |
| Android (default subTarget) |
RGB |
RGB 24 bit |
RGB Compressed ETC |
RGB Compressed ETC |
RGB Compressed ETC |
|
RGBA |
RGBA 32 bit |
RGBA Compressed ETC2 |
RGBA Compressed ETC2 |
RGBA Compressed ETC2 |
iOS
|
RGB |
RGB 24 bit |
RGB Compressed PVRTC 4 bits |
RGB Compressed PVRTC 4 bits |
RGB Compressed PVRTC 2 bits |
|
RGBA |
RGBA 32 bit |
RGBA Compressed PVRTC 4 bits |
RGBA Compressed PVRTC 4 bits |
RGBA Compressed PVRTC 2 bits |
| tvOS |
RGB |
RGB 24 bit |
RGB Compressed ASTC 6x6 block |
RGB Compressed ASTC 4x4 block |
RGB Compressed ASTC 8x8 block |
|
RGBA |
RGBA 32 bit |
RGBA Compressed ASTC 6x6 block |
RGBA Compressed ASTC 4x4 block |
RGBA Compressed ASTC 8x8 block |
|
RGBA |
RGBA 32 bit |
RGBA 16 bit |
RGBA 16 bit |
RGBA 16 bit |
All supported Texture compression formats
The following table shows the
Texture
compression format options available on each
platform, and the resulting compressed file size (based on a
256px-square image). Choosing a Texture compression format is a
balance between file size and quality; the higher the quality, the
greater the file size. In the description below, see the final file
size of a in-game Texture of 256 by 256
pixels
.
When you use a Texture compression format that is not supported on
the target platform, the Textures are decompressed to RGBA 32 and
stored in memory alongside the compressed Textures. When this
happens, time is lost decompressing Textures, and memory is lost
because you are storing them twice. In addition, all platforms have
different hardware, and are optimised to work most efficiently with
specific compression formats; choosing non-compatible formats can
impact your game’s performance. The table below shows supported
platforms for each compression format.
Notes on the table below:
- RGB is a color model in which red, green
and blue are added together in various ways to reproduce a broad
array of colors.
- RGBA is a version of
RGB with an alpha channel, which
supports blending and opacity alteration.
- Crunch compression is a lossy compression
format (meaning that parts of the data are lost during compression) on top of DXT
or ETC Texture compression. Textures are decompressed to DXT or ETC
on the CPU, and then uploaded to the GPU at run time. Crunch
compression helps the Texture use the lowest possible amount of
space on disk and for downloads. Crunch Textures can take a long
time to compress, but decompression at run time is very
fast.
| Texture compression format |
Description |
Size
for a 256x256 pixel Texture |
Platform Support |
| RGB Compressed DXT1 |
Compressed unsigned normalised integer RGB Texture. |
32KB (4 bits per pixel) |
Windows, Linux, macOS, PS4, XBox One, Android (Nvidia Tegra and
Intel Bay Trail), WebGL
Note: With linear
rendering on web browser that doesn’t support sRGB DXT,
textures are uncompressed at run time to RGBA32. |
| RGB Crunched DXT1 |
Similar to RGB Compressed DXT1, but compressed using Crunch
compression. See Notes, above, for more on crunch compression. |
Variable, depending on the complexity of the content in the
texture. |
Windows, Linux, macOS, PS4, XBox One, Android (Nvidia Tegra and
Intel Bay Trail), WebGL
Note: With linear
rendering on a web browser that doesn’t support sRGB
DXT, textures ar |
