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<BLOCKQUOTE>
<H1><A NAME="NAME"><A NAME="1">NAME
</A></A></H1>
<P>
<B>smoothstep</B> - interpolate smoothly between two input values based on a third
</P>
<H1><A NAME="SYNOPSIS"><A NAME="2">SYNOPSIS
</A></A></H1>
<PRE> float smoothstep(float a, float b, float x);
float1 smoothstep(float1 a, float1 b, float1 x);
float2 smoothstep(float2 a, float2 b, float2 x);
float3 smoothstep(float3 a, float3 b, float3 x);
float4 smoothstep(float4 a, float4 b, float4 x);
half smoothstep(half a, half b, half x);
half1 smoothstep(half1 a, half1 b, half1 x);
half2 smoothstep(half2 a, half2 b, half2 x);
half3 smoothstep(half3 a, half3 b, half3 x);
half4 smoothstep(half4 a, half4 b, half4 x);
fixed smoothstep(fixed a, fixed b, fixed x);
fixed1 smoothstep(fixed1 a, fixed1 b, fixed1 x);
fixed2 smoothstep(fixed2 a, fixed2 b, fixed2 x);
fixed3 smoothstep(fixed3 a, fixed3 b, fixed3 x);
fixed4 smoothstep(fixed4 a, fixed4 b, fixed4 x);
</PRE>
<H1><A NAME="PARAMETERS"><A NAME="3">PARAMETERS
</A></A></H1>
<DL>
<DT><STRONG>a
</STRONG></DT>
<DD>
<P>
Scalar or vector minimum reference value(s).
</P>
<DT><STRONG>b
</STRONG></DT>
<DD>
<P>
Scalar or vector minimum reference value(s).
</P>
<DT><STRONG>x
</STRONG></DT>
<DD>
<P>
Scalar or vector.
</P>
</DD></DL>
<H1><A NAME="DESCRIPTION"><A NAME="4">DESCRIPTION
</A></A></H1>
<P>
Interpolates smoothly from <I>0</I> to <I>1</I> based on <I>x</I> compared to <I>a</I> and <I>b</I>.
</P>
<DL>
<DT><STRONG></STRONG></DT>
<DD>
<P>
1) Returns <I>0</I> if <I><x < a < b</I>> or <I><x </I> a > b>>
</P>
<DT><STRONG></STRONG></DT>
<DD>
<P>
1) Returns <I>1</I> if <I><x < b < a</I>> or <I><x </I> b > a>>
</P>
<DT><STRONG></STRONG></DT>
<DD>
<P>
3) Returns a value in the range <I>[0,1]</I> for the domain <I>[a,b]</I>.
</P>
</DD></DL>
<P>
The slope of <CODE>smoothstep(a,b,a)</CODE> and <CODE>smoothstep(a,b,b)</CODE> is zero.
</P>
<P>
For vectors, the returned vector contains the smooth interpolation of each element of the vector <I>x</I>.
</P>
<H1><A NAME="REFERENCE_IMPLEMENTATION"><A NAME="5">REFERENCE IMPLEMENTATION
</A></A></H1>
<P>
<B>smoothstep</B> for <B>float</B> scalars could be implemented this way:
</P>
<PRE> float smoothstep(float a, float b, float x)
{
float t = saturate((x - a)/(b - a));
return t*t*(3.0 - (2.0*t));
}
</PRE>
<H1><A NAME="PROFILE_SUPPORT"><A NAME="6">PROFILE SUPPORT
</A></A></H1>
<P>
<B>smoothstep</B> is supported in all profiles except <A HREF="fp20.html">fp20</A>.
</P>
<H1><A NAME="SEE_ALSO"><A NAME="7">SEE ALSO
</A></A></H1>
<P>
<A HREF="clamp.html"><I>clamp</I></A>, <A HREF="saturate.html">saturate</A>, <A HREF="step.html">step</A>
</P>
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