depth linear

float ConvertDepth( float depthFromTex, float4 cameraParams )
{
const float near = cameraParams.z;
const float far = cameraParams.w;
const float nearMulFar = cameraParams.x;
const float nearSubFar = cameraParams.y;
return nearMulFar / ( depthFromTex * nearSubFar + far );
}