1.1 --- a/src/volume.cc	Mon Feb 03 01:30:47 2014 +0200
     1.2 +++ b/src/volume.cc	Mon Feb 03 02:52:46 2014 +0200
     1.3 @@ -178,6 +178,14 @@
     1.4  	x = (x - low) / (high - low);
     1.5  	return x * x * (3.0 - 2.0 * x);
     1.6  }
     1.7 +
     1.8 +float transfer_function(float x, float low_thres, float high_thres)
     1.9 +{
    1.10 +	float dt = 0.25 * (high_thres - low_thres);
    1.11 +	return smoothstep(x, low_thres - dt, low_thres + dt) *
    1.12 +		(1 - smoothstep(x, high_thres - dt, high_thres + dt));
    1.13 +}
    1.14 +
    1.15  static float cb_eval(float x, float y, float z)
    1.16  {
    1.17  	const Image *img = cur_vol->get_slice_by_z((z + 1) / 2.0);
    1.18 @@ -187,8 +195,7 @@
    1.19  	int py = (y + 1) / 2.0 * img->get_height();
    1.20  
    1.21  	float val = pixels[px + img->get_width() * py];
    1.22 -	float dt = 0.25 * (high_thres - low_thres);
    1.23 -	return smoothstep(val, low_thres - dt, low_thres + dt) * (1 - smoothstep(val, high_thres - dt, high_thres + dt));
    1.24 +	return transfer_function(val, low_thres, high_thres);
    1.25  }
    1.26  
    1.27  static void cb_vertex(float x, float y, float z)