PS3 GLSL Depth to position

depth_to_position.glsl

//Convert to 24bit 
const float3 depthFactor = float3(65536.0f/16777215.0f, 256.0f/16777215.0f, 1.0f/16777215.0f ); 
float GetDepth( float4 raw_depth ) 
{ 
    return dot( round( raw_depth.xyz * 255.0f.xxx ), depthFactor.xyz); 
}
 
float2 texcoord = in.vpos/g_Resolution; 
pos.xy = in.vpo; 
pos.z = GetDepth( tex2D(g_Depthmap,texcoord).rgba ); 
pos = 2.0*pos-1.0; 
 
float4 Clip = mul(g_MatrixInverseViewProj,float4(pos,1.0)); 
pos = (Clip.xyz / Clip.w);