Streaming Light Rays 2
This tutorial can only be completed using Bryce4 or later.

Bryce 4 has an additional option in the light editor called Ranged Falloff. In the manual the only mention of it appears to be on Page 363 where it says "Ranged Falloff causes the light to change abruptly from full intensity to zero (no illumination) after a defined distance range." There is no mention of how you define the distance range. This tutorial attempts to explain the use of this option with respect to streaming light rays through a window.To follow this tutorial you should set up a scene as in the first Streaming Light Rays tutorial but select Ranged Falloff instead of Linear Falloff or Squared Falloff
Here is the familiar set up with Ranged Falloff selected and the Brightness set to 100. The Fuzziness or Softness of the light is set to 60.

It is this setting which determines the range of the light.

If you have Bryce 4.01 then to set the range or length of the light effect hold down the Alt/Opt key and drag left or right on the light preview window.

Here the Softness/Range setting is set to 65, notice the shorter length of the light rays.
Here the Softness/Range setting is set to 70, notice the even shorter length of the light rays.

You will notice that the Range control is in this case very coarse over a short range of values. 60 to 70 in this case using a value of 100 for the brightness. the range of useful values will vary depending on the brightness setting.
Since the length of the light rays is measured from the light itself, you can alter the effect greatly by just moving the light further away as in this case. Here the values of 100 and 60 are used as in the first image but the light has been moved away from the window (and raised) to give an entirely different effect.
Here the brightness has been reduced to 30 with a range of 60 for quite a pleasing effect.

You may have noticed that there is no shadow of the window bars on the floor. Also that there appears to be an overspill of light around the pool of light on the floor.
This is where another Bryce variable comes into play, it's Shadow Intensity.

You can find it in the Sky Lab on the Sun and Moon page. You can also drag across the Shadow Colour thumbnail in the Sky & Fog Palette. Apparently this was also in Bryce 3 but I have to admit I never noticed it.
These three images show the effect of Shadow Intensity on the light rays. The settings used in these three are Brightness = 100 and Range = 65.

As you can see these two controls allow a great range of lighting effects to be achieved.

Have fun.

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