ph_box0_center                    = 0.0,  0.9,  0.0
ph_box0_size                    = 0.35, 0.9,  0.35
ph_box1_center                    = 0.0,  0.75,  0.0
ph_box1_size                    = 0.35, 0.75,  0.35
ph_box2_center                    = 0.0,  0.6,  0.0
ph_box2_size                    = 0.35, 0.6,  0.35

float4 combine_bloom( float3  low, float4 high)    
{
        return float4( low + high*high.a, 1.h );
}

float4 combine_bloom( float3  low, float4 high)    
{
        return float4( low + high*high.a*0.5h, 1.h );
}