GPU Pro 6

1. Practical Screen-Space Soft Shadows 307

//input : float value in range [0 . . . 1 ]

uint float_to_r8 ( float val )

{

const uint bits =8;

uint precision_scaler = uint( pow( uint (2) , bits )) − uint(1) ;

return uint( floor ( precision_scaler val ));

}

uint rgba8_to_uint ( vec4 val )

{

uint res = float_to_r8 ( val . x ) << 24;

res |= float_to_r8 ( val . y ) << 16;

res |= float_to_r8 ( val . z ) << 8;

res |= float_to_r8 ( val . w ) << 0;

return res ;

}

Listing 1.2. A function to pack an RGBA8 value into an R32F float.

float threshold =0.25;

float filter_size =

// account for li g h t si z e ( af fe ct s penumbra s i z e )

light_size

//anisotropic term, varies w