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API > API/Runtime > API/Runtime/Engine > API/Runtime/Engine/FEmitter
Description
Emits the partial derivative of given value. This function differentiates the given value with respect to the given axis. If differentiation is not possible, it returns a poison value to indicate an error. This API can be used regardless of the stages value will execute in. Hardware partial derivatives will be used by default where available. If not available, the analytical derivative will be computed instead.
| Name | PartialDerivative |
| Type | function |
| Header File | /Engine/Source/Runtime/Engine/Public/Materials/MaterialIREmitter.h |
| Include Path | #include "Materials/MaterialIREmitter.h" |
| Source | /Engine/Source/Runtime/Engine/Private/Materials/MaterialIREmitter.cpp |
FValueRef PartialDerivative
(
FValueRef Value,
EDerivativeAxis Axis
)
A new FValueRef representing the partial derivative, or a poison value if invalid.
Parameters
| Name | Remarks |
|---|---|
| Value | The value to differentiate. |
| Axis | The axis along which to compute the partial derivative (X for ddx, Y for ddy). |