--- layout: stdlib-reference --- # faceforward ## Description Flip vector to face forward, if needed. ## Signature

vector<T, N> faceforward<T, N:int>(
    vector<T, N> n,
    vector<T, N> i,
    vector<T, N> ng)
    where T : __BuiltinFloatingPointType;

## Generic Parameters #### T: [\_\_BuiltinFloatingPointType](../interfaces/0_builtinfloatingpointtype-029hm/index.html) #### N : int ## Parameters #### n : [vector](../types/vector/index.html)\<[T](../types/vector/index.html#typeparam-T), [N](../types/vector/index.html#decl-N)\> The vector to orient. #### i : [vector](../types/vector/index.html)\<[T](../types/vector/index.html#typeparam-T), [N](../types/vector/index.html#decl-N)\> The incident vector. #### ng : [vector](../types/vector/index.html)\<[T](../types/vector/index.html#typeparam-T), [N](../types/vector/index.html#decl-N)\> The geometric normal vector. ## Return value n if the dot product of ng and i is less than 0, otherwise -n. ## Availability and Requirements Defined for the following targets: #### hlsl Available in all stages. #### glsl Available in all stages. #### cpp Available in all stages. #### cuda Available in all stages. #### metal Available in all stages. #### wgsl Available in all stages. #### spirv Available in all stages.