TG Reflectance Ramp

PARAMETERS

Parameters Controlled by Ramps

Ambient, Diffuse, Shininess, Reflection and Transmission

Range : -100 to 100 for each

All these work in the conventional way, just as in other shaders, with the exception that there are Min and Max settings for the relevant parameters. The Min parameters set the value to be used when black is read from the associated Ramp, while the Max parameters set the value to be used when white is read from the associated Ramp.

Another unusual feature is the range (a by-product of having them set up as vector variables in ShaderLab2), which allows very high values (which would make the shader useful for glows, or as a layered shader with the bare minimum of transparency in that layer), and also allows negative values (which could lead to some very unusual effects indeed!).

Process Internal Reflections

Range : Unchecked / Checked

If checked, then when transmission results in the ray intercepting an internal surface, reflection processing is carried out for that surface (using the reflection settings as for every other surface). If unchecked, then no reflection processing is done for internal surfaces (although diffuse, shininess and transmission are still carried out).

Although checking this flag can make the resulting render more realistic or interesting, it can also add significantly to render times.

Reflection and Transmission Contribution

Range : 0 to 1

This works just like in any other reflection shaders - higher values let the reflected ray bounce (from reflection or transmission) more times, giving more “reflections of reflections”, at the expense of longer render times.

Refractive Index, Roughness, Specular Tint, Specular Colour

These work just like in any other reflection shader.

Use True Angle

Range : Unchecked / Checked

When unchecked, the shader works with the Cosine of the angle between the surface normal and direction of view, which introduces a non-linear sweep to the values (so what you see in the Ramp isn’t exactly what you get in the render).

When checked, the shader does the extra bit of processing (so may be a little slower) in order to work back to the linear sweep of the angle between the two vectors, so moves through the Ramp values in a linear fashion.

Note that this affects all four Ramps.

Use Diffuse Ramp for Ambient

Range : Unchecked / Checked

When unchecked, the shader uses the “Ambient Min” value as the overall ambient value, which affects the whole object equally.

When checked, the shader applies the “Angle Diffuse Ramp” to the ambient setting, so that it varies across the object’s surface. This can actually make the dreaded ambient setting into something useful! Note that although it must share the same Ramp image as the Diffuse channel, you can reverse the effects between the two by setting a higher “Ambient Min” than “Ambient Max”, so it remains very flexible.

Angle Diffuse Ramp, Angle Specular Ramp, Angle Reflectance Ramp, Angle Transmission Ramp

Range : Images

The Ramps for the Diffuse, Specular, Reflectance and Transparency channels in the material. The leftmost edge of each Ramp is read for surfaces which are at right angles to the direction of view (the outer edge of a sphere, for example), while the rightmost edge of each Ramp is read for surfaces which are facing back toward the direction of view (the innermost surfaces of a sphere, for example).

When black is returned from the Ramp, the associated Min value is used, and when white is read from the Ramp, the associated Max value is used.

TG Reflectance Ramp Intro

TG Reflectance Ramp Parameters

TG Pack 3 Index