Version: 2018.3 (switch to 2019.1b or 2017.4)
Shader Level of Detail
Debugging DirectX 11/12 shaders with Visual Studio
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Texture arrays

Similar to regular 2D textures (Texture2D class, sampler2D in shaders), cube maps (CubemapA collection of six square textures that can represent the reflections in an environment or the skybox drawn behind your geometry. The six squares form the faces of an imaginary cube that surrounds an object; each face represents the view along the directions of the world axes (up, down, left, right, forward and back). More info
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class, samplerCUBE in shaders), and 3D textures (Texture3D class, sampler3D in shaders), Unity also supports 2D texture arrays.

A texture array is a collection of same size/format/flags 2D textures that look like a single object to the GPU, and can be sampled 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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with a texture element index. They are useful for implementing custom 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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renderingThe process of drawing graphics to the screen (or to a render texture). By default, the main camera in Unity renders its view to the screen. More info
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systems or other special effects where you need an efficient way of accessing many textures of the same size and format. Elements of a 2D texture array are also known as slices, or layers.

Platform Support

Texture arrays need to be supported by the underlying graphics API and the GPU. They are available on:

  • Direct3D 11/12 (Windows, Xbox One)
  • OpenGL CoreThe back-end Unity uses to support the latest OpenGL features on Windows, MacOS X and Linux. More info
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    (Mac OS X, Linux)
  • Metal (iOS, Mac OS X)
  • OpenGL ES 3.0 (Android, iOS, WebGL 2.0)
  • PlayStation 4

Other platforms do not support texture arrays (OpenGL ES 2.0 or WebGL 1.0). Use SystemInfo.supports2DArrayTextures to determine texture array support at runtime.

Creating and manipulating texture arrays

As there is no texture import pipeline for texture arrays, they must be created from within your scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
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. Use the Texture2DArray class to create and manipulate them. Note that texture arrays can be serialized as assetsAny media or data that can be used in your game or Project. An asset may come from a file created outside of Unity, such as a 3D model, an audio file or an image. You can also create some asset types in Unity, such as an Animator Controller, an Audio Mixer or a Render Texture. More info
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, so it is possible to create and fill them with data from editor scripts.

Normally, texture arrays are used purely within GPU memory, but you can use Graphics.CopyTexture, Texture2DArray.GetPixels and Texture2DArray.SetPixels to transfer pixelsThe smallest unit in a computer image. Pixel size depends on your screen resolution. Pixel lighting is calculated at every screen pixel. More info
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to and from system memory.

Using texture arrays as render targets

Texture array elements may also be used as render targets. Use RenderTexture.dimension to specify in advance whether the render target is to be a 2D texture array. The depthSlice argument to Graphics.SetRenderTarget specifies which mipmap level or cube map face to render to. On platforms that support “layered rendering” (i.e. geometry shaders), you can set the depthSlice argument to –1 to set the whole texture array as a render target. You can also use a geometry shader to render into individual elements.

Using texture arrays in shaders

Since texture arrays do not work on all platforms, shaders need to use an appropriate compilation target or feature requirement to access them. The minimum shader model compilation target that supports texture arrays is 3.5, and the feature name is 2darray.

Use these macros to declare and sample texture arrays:

  • UNITY_DECLARE_TEX2DARRAY(name) declares a texture array sampler variable inside HLSL code.
  • UNITY_SAMPLE_TEX2DARRAY(name,uv) samples a texture array with a float3 UV; the z component of the coordinate is an array element index.
  • UNITY_SAMPLE_TEX2DARRAY_LOD(name,uv,lod) samples a texture array with an explicit mipmap level.

Examples

The following shader example samples a texture array using object space vertex positions as coordinates:

Shader "Example/Sample2DArrayTexture"
{
    Properties
    {
        _MyArr ("Tex", 2DArray) = "" {}
        _SliceRange ("Slices", Range(0,16)) = 6
        _UVScale ("UVScale", Float) = 1.0
    }
    SubShader
    {
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            // texture arrays are not available everywhere,
            // only compile shader on platforms where they are
            #pragma require 2darray
            
            #include "UnityCG.cginc"

            struct v2f
            {
                float3 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            float _SliceRange;
            float _UVScale;

            v2f vert (float4 vertex : POSITION)
            {
                v2f o;
                o.vertex = mul(UNITY_MATRIX_MVP, vertex);
                o.uv.xy = (vertex.xy + 0.5) * _UVScale;
                o.uv.z = (vertex.z + 0.5) * _SliceRange;
                return o;
            }
            
            UNITY_DECLARE_TEX2DARRAY(_MyArr);

            half4 frag (v2f i) : SV_Target
            {
                return UNITY_SAMPLE_TEX2DARRAY(_MyArr, i.uv);
            }
            ENDCG
        }
    }
}

See Also


  • 2018–03–20 Page amended with editorial review
  • Shader #pragma directives added in Unity 2018.1

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Shader Level of Detail
Debugging DirectX 11/12 shaders with Visual Studio