gentype
smoothstep
(
 gentype edge0, 
gentype edge1,  
gentype x) 
gentype
smoothstep
(
 float edge0, 
float edge1,  
gentype x) 
gentype smoothstep (double edge0 ,
double edge1 ,
gentype x ) // if double extension enabled

gentype smoothstep (half edge0 ,
half edge1 ,
gentype x ) // if half extension enabled

Returns 0.0 if x
less than or equal to edge0
and 1.0 if x
greater than or equal to edge1
and performs smooth Hermite interpolation between 0 and 1 when edge0
< x
< edge1
. This is useful in cases where you would want a threshold function with a smooth transition.
This is equivalent to:
gentype t;
t = clamp(((x  edge0) / (edge1  edge0), 0, 1);
return t * t * (3  2 * t );
Results are undefined if edge0
greater than or equal to edge1
or if x
,
edge0
or edge1
is a NaN.
This function can be implemented using contractions such as mad or fma.
Builtin common functions operate componentwise and the description is percomponent. We use the generic type name gentype to indicate that the function can take float, float2, float4, float8, or float16 as the type for the arguments.
The builtin common functions are implemented using the round to nearest even rounding mode.
If extended with cl_khr_fp64, generic type name gentype may indicate double and double{24816} as arguments and return values. If extended with cl_khr_fp16, generic type name gentype may indicate half and half{24816} as arguments and return values.