ddx

Returns the partial derivative of the specified value with respect to the screen-space x-coordinate.

ret ddx(x)

This function computes the partial derivative with respect to the screen-space x-coordinate. To compute the partial derivative with respect to the screen-space y-coordinate, use the ddy function.

This function is only supported in pixel shaders.

Parameters

Item	Description
x	[in] The specified value.

Return Value

The partial derivative of the x parameter.

Type Description

Name	Template Type	Component Type	Size
x	scalar, vector, or matrix	float	any
ret	same as input x	float	same dimension(s) as input x

Minimum Shader Model

This function is supported in the following shader models.

Shader Model	Supported
Shader Model 5 and higher shader models	yes
Shader Model 4	yes
Shader Model 3 (DirectX HLSL)	yes
Shader Model 2 (DirectX HLSL)	yes in ps_2_x; unsupported in ps_2_0.
Shader Model 1 (DirectX HLSL)	no

This function is supported in the following types of shaders:

Vertex	Hull	Domain	Geometry	Pixel	Compute
				x

See also

Intrinsic Functions (DirectX HLSL)