GPU Pro 5

184 II Lighting and Shading

float2 texcoords = input . tex . xy ;

// Unpack c l i p pos i tion from texcoords and depth .

float depth = depthBuffer . SampleLevel ( pointSampler ,

texcoords ,0.0f );

float4 currClip = unpackClipPos ( texcoords , depth );

// Unpack into previous homogenous coordinates :

// inverse(view projection) previous (view projection ) .

float4 prevHomogenous = mul ( currClip ,

invViewProjPrevViewProjMatrix);

// Unpack homogenous coordinate into clip −space coordinate.

float4 prevClip = float4 ( prevHomogenous . xyz /

prevHomogenous . w ,1.0f );

// Unpack into screen coordinate [−1, 1] into [0 , 1] range and

// flip the y coordinate.