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SampleLevel (DirectX HLSL Texture Object)

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Samples a texture using a mipmap-level offset.

<Template Type> Object.SampleLevel( sampler_state S, float Location, float LOD [, int Offset] );

This function is similar to Sample except that it uses the LOD level (in the last component of the location parameter) to choose the mipmap level. For example, a 2D texture uses the first two components for uv coordinates and the third component for the mipmap level.

Parameters

Item Description
Object
 Any texture-object type (except Texture2DMS and Texture2DMSArray).
S
 [in] A Sampler state. This is an object declared in an effect file that contains state assignments.
Location
 [in] The texture coordinates. The argument type is dependent on the texture-object type.
Texture-Object Type Parameter Type
Texture1D float
Texture1DArray, Texture2D float2
Texture2DArray, Texture3D, TextureCube float3
TextureCubeArray float4

If the texture object is an array, the last component is the array index.

LOD

[in] A number that specifies the mipmap level (internally clamped to the smallest map level). If the value is = 0, the zero'th (biggest map) is used. The fractional value (if supplied) is used to interpolate between two mipmap levels.

Offset

[in] An optional texture coordinate offset, which can be used for any texture-object type; the offset is applied to the location before sampling. The texture offsets need to be static. The argument type is dependent on the texture-object type. For more info, see Applying texture coordinate offsets.

Texture-Object Type Parameter Type
Texture1D, Texture1DArray int
Texture2D, Texture2DArray int2
Texture3D int3
TextureCube, TextureCubeArray not supported

Return Value

The texture's template type, which may be a single- or multi-component vector. The format is based on the texture's DXGI_FORMAT.

Minimum Shader Model

This function is supported in the following shader models.

vs_4_0 vs_4_1 ps_4_0 ps_4_1 gs_4_0 gs_4_1
x x x x x x
  1. TextureCubeArray is available in Shader Model 4.1 or higher.
  2. Shader Model 4.1 is available in Direct3D 10.1 or higher.

Example

This partial code example is from the Instancing.fx file in the Instancing10 Sample.

// Object Declarations
Texture1D g_txRandom;

SamplerState g_samPoint
{
    Filter = MIN_MAG_MIP_POINT;
    AddressU = Wrap;
    AddressV = Wrap;
};

    
// Shader body calling the intrinsic function
float3 RandomDir(float fOffset)
{   
    float tCoord = (fOffset) / 300.0;
    return g_txRandom.SampleLevel( g_samPoint, tCoord, 0 );
   ...

Texture-Object