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Fresnel shader

    The Fresnel effect states that the properties of a surface change as the angle you're viewing it at changes. So, for example, a surface may be more transparent when you look at it straight on, and less transparent when looking at it edgewise. It occurs because of the thickness of material you're looking through changes. For example, when you look straight up into the sky, it's only a few dozen miles worth of atmosphere you have to look through. When you look out to the horizon, you're looking through hundreds of miles of atmosphere. That's why the sun is tinted red more at sunset than at midday.
    Now, let's go through the controls of RealiTools_Fresnel one-by-one:

Channel to Effect The Fresnel shader has the ability to work on the Diffuse, Luminosity, Specularity, Transparency, or Reflectivity channel. Use this to choose which. (Note that if you need more than one channel to be affected, you can apply another instance of the plug-in.)

Fresnel effect % By changing this, you can change the amount that the Fresnel effect is present. Think of it as a "Texture Opacity" for the Fresnel shader.

Surface Blend This is an option that is, unique to the Fresnel shader in RealiTools. It essentially lets you change the opacity of the Fresnel effect by the Fresnel effect! When you choose one of the blending options other than none, the previous surface value in that channel will show through, based on what you choose. If you choose "High values", the previous surface settings will show through completely where the Fresnel-calculated value is 100%, and not show through at all where the Fresnel-calculated value is 0%. Just the opposite occurs when you choose "Low values", and if you pick "In-between", the previous surface settings will show through the most when the Fresnel-calculated effect is 50%.

Limit surface values from 0% to 100% This option is pretty self-explanatory. Basically, it's possible to set LightWave's surface settings above 100% and below 0%. The contrast formula does this (though not intentionally). Sometimes this can look pretty bad. Try setting contrast up to 100% on a transparent surface sometime and you'll see the effect. By enabling this option, you tell the Fresnel shader to prevent the surface from going outside of the usual 0-100% range.

Glancing value % This is the surface value (for the channel you've chosen) when the surface is edge-on to the camera.

Normalized value % This is the surface value (for the channel you've chosen) when the surface is directly facing the camera.

Contrast % By increasing or decreasing this, you can sharpen or soften (respectively) the transition between the glancing and normalized values. Values from -100% to 100% are allowed.

Bias % This value will be added to the Fresnel effect. Say, for instance, that the effect came out to 50% transparency at a certain point on a surface. If you had entered 25% into this control, the result would be 75% at that point. By changing this, you can change the point at which the transition occurs on the surface, which becomes important when you increase the contrast.

Tutorial
    A full-scale tutorial for Fresnel would be tough, but here's a brief introduction. We'll make a snow-globe look better with the Fresnel shader.

1. Open Layout and load snoglobe.lwo.
2. Test-render a frame. Doesn't that glass sphere look kinda...well...pathetic?
3. Open the Surfaces panel. Switch to the surface named "Sno-globe glass".
4. Activate RT_Fresnel and click the Options button.
5. Choose Transparency for Channel to Effect.
6. Enable the Limit surface values from 0% to 100% button.
7. Set the Glancing value to 25 %, and the Contrast to 50%.
8. Click OK and test render another frame. Doesn't that look a lot better?

Tutorial
In this tutorial, we'll use the Fresnel shader to give a new type of hand-drawn look to an object.

1. Open Layout and load Goo.lwo.
2. Under the Effects panel, set the background color to 255, 255, 255.
3. Open the Surfaces panel. Switch to the surface named "Goo".
4. Change the surface color to 255, 255, 255, and turn the Diffuse down to 0%.
5. Activate the RealiTools_Fresnel plug-in, and click the Options button.
6. Choose Luminosity for the Channel to Effect.
7. Set the Contrast to 90%, and the Bias to 10%. Click OK.
8. Turn on antialiasing if you want, and render.

Notice how this works : surfaces that curve away from the camera more gradually get much larger outlines. Surfaces that curve away very sharply get very thin outlines, or none at all. If you need lines along the entire outside edge of the object, try Cel-look edges as well as this, and you'll get at least some edges everywhere. You can use several variations on this effect, too. If you give the surfaces you're using colors other than white, you can get something that looks like a TV cartoon. If you add specularity on top of that (just a low amount), it'll look like an image on a comic book's page. If you want to use this with the Super Cel Shader, you can. We recommend against it, because it just doesn't look very good. If you do really get the urge to try it, though, make sure to apply the cel shader first, then apply RealiTools_Fresnel.

Channel to Effect	The Fresnel shader has the ability to work on the Diffuse, Luminosity, Specularity, Transparency, or Reflectivity channel. Use this to choose which. (Note that if you need more than one channel to be affected, you can apply another instance of the plug-in.)
Fresnel effect %	By changing this, you can change the amount that the Fresnel effect is present. Think of it as a "Texture Opacity" for the Fresnel shader.
Surface Blend	This is an option that is, unique to the Fresnel shader in RealiTools. It essentially lets you change the opacity of the Fresnel effect by the Fresnel effect! When you choose one of the blending options other than none, the previous surface value in that channel will show through, based on what you choose. If you choose "High values", the previous surface settings will show through completely where the Fresnel-calculated value is 100%, and not show through at all where the Fresnel-calculated value is 0%. Just the opposite occurs when you choose "Low values", and if you pick "In-between", the previous surface settings will show through the most when the Fresnel-calculated effect is 50%.
Limit surface values from 0% to 100%	This option is pretty self-explanatory. Basically, it's possible to set LightWave's surface settings above 100% and below 0%. The contrast formula does this (though not intentionally). Sometimes this can look pretty bad. Try setting contrast up to 100% on a transparent surface sometime and you'll see the effect. By enabling this option, you tell the Fresnel shader to prevent the surface from going outside of the usual 0-100% range.
Glancing value %	This is the surface value (for the channel you've chosen) when the surface is edge-on to the camera.
Normalized value %	This is the surface value (for the channel you've chosen) when the surface is directly facing the camera.
Contrast %	By increasing or decreasing this, you can sharpen or soften (respectively) the transition between the glancing and normalized values. Values from -100% to 100% are allowed.
Bias %	This value will be added to the Fresnel effect. Say, for instance, that the effect came out to 50% transparency at a certain point on a surface. If you had entered 25% into this control, the result would be 75% at that point. By changing this, you can change the point at which the transition occurs on the surface, which becomes important when you increase the contrast.