<HTML> <HEAD> <TITLE>lerp</TITLE> <STYLE TYPE="text/css" MEDIA=screen> <!-- BODY { font-family: Arial,Helvetica; } BLOCKQUOTE { margin: 10pt; } H1,A { color: #336699; } /*** Top menu style ****/ .mmenuon { font-family: Arial,Helvetica; font-weight: bold; text-decoration: none; color: #ff6600; font-size: 10pt; } .mmenuoff { font-family: Arial,Helvetica; font-weight: bold; text-decoration: none; color: #ffffff; font-size: 10pt; } .cpyright { font-family: Arial,Helvetica; font-weight: bold; text-decoration: none; color: #ffffff; font-size: xx-small; } .cpyrightText { font-family: Arial,Helvetica; font-weight: bold; text-decoration: none; color: #ffffff; font-size: xx-small; } .sections { font-family: Arial,Helvetica; font-weight: bold; text-decoration: none; color: #336699; font-size: 11pt; } .dsections { font-family: Arial,Helvetica; font-weight: bold; text-decoration: none; color: #336699; font-size: 12pt; } .slink { font-family: Arial,Helvetica; font-weight: normal; text-decoration: none; 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float1 lerp(float1 a, float1 b, float1 w); float2 lerp(float2 a, float2 b, float2 w); float3 lerp(float3 a, float3 b, float3 w); float4 lerp(float4 a, float4 b, float4 w); float1 lerp(float1 a, float1 b, float w); float2 lerp(float2 a, float2 b, float w); float3 lerp(float3 a, float3 b, float w); float4 lerp(float4 a, float4 b, float w); half lerp(half a, half b, half w); half1 lerp(half1 a, half1 b, half1 w); half2 lerp(half2 a, half2 b, half2 w); half3 lerp(half3 a, half3 b, half3 w); half4 lerp(half4 a, half4 b, half4 w); half1 lerp(half1 a, half1 b, half w); half2 lerp(half2 a, half2 b, half w); half3 lerp(half3 a, half3 b, half w); half4 lerp(half4 a, half4 b, half w); fixed lerp(fixed a, fixed b, fixed w); fixed1 lerp(fixed1 a, fixed1 b, fixed1 w); fixed2 lerp(fixed2 a, fixed2 b, fixed2 w); fixed3 lerp(fixed3 a, fixed3 b, fixed3 w); fixed4 lerp(fixed4 a, fixed4 b, fixed4 w); fixed1 lerp(fixed1 a, fixed1 b, fixed w); fixed2 lerp(fixed2 a, fixed2 b, fixed w); fixed3 lerp(fixed3 a, fixed3 b, fixed w); fixed4 lerp(fixed4 a, fixed4 b, fixed w); </PRE> <H1><A NAME="PARAMETERS"><A NAME="3">PARAMETERS </A></A></H1> <DL> <DT><STRONG>a </STRONG></DT> <DD> <P> Vector or scalar to weight; returned when <I>w</I> is zero. </P> <DT><STRONG>b </STRONG></DT> <DD> <P> Vector or scalar to weight; returned when <I>w</I> is one. </P> <DT><STRONG>w </STRONG></DT> <DD> <P> Vector or scalar weight. </P> </DD></DL> <H1><A NAME="DESCRIPTION"><A NAME="4">DESCRIPTION </A></A></H1> <P> Returns the linear interpolation of <I>a</I> and <I>b</I> based on weight <I>w</I>. </P> <P> <I>a</I> and <I>b</I> are either both scalars or both vectors of the same length. The weight <I>w</I> may be a scalar or a vector of the same length as <I>a</I> and <I>b</I>. <I>w</I> can be any value (so is not restricted to be between zero and one); if <I>w</I> has values outside the [0,1] range, it actually extrapolates. </P> <P> <B>lerp</B> returns <I>a</I> when <I>w</I> is zero and returns <I>b</I> when <I>w</I> is one. </P> <H1><A NAME="REFERENCE_IMPLEMENTATION"><A NAME="5">REFERENCE IMPLEMENTATION </A></A></H1> <P> <B>lerp</B> for <B>float3</B> vectors for <I>a</I> and <I>b</I> and a <B>float</B> w could be implemented like this: </P> <PRE> float3 lerp(float3 a, float3 b, float w) { return a + w*(b-a); } </PRE> <H1><A NAME="PROFILE_SUPPORT"><A NAME="6">PROFILE SUPPORT </A></A></H1> <P> <B>lerp</B> is supported in all profiles. </P> <H1><A NAME="SEE_ALSO"><A NAME="7">SEE ALSO </A></A></H1> <P> <A HREF="saturate.html"><I>saturate</I></A>, <A HREF="smoothstep.html"><I>smoothstep</I></A>, <A HREF="step.html"><I>step</I></A> </P> </BLOCKQUOTE> </BODY>