Re: Controlling the Terminator in XSI

[Joey Ponthieux <j.g.ponthieux(at)LaRC.NASA.GOV>]

Duh, do I feel stupid. I sent you a link to instructions on how to build 
a planetary limb, not a terminator. I sent that link off so quickly I 
didnt pay attention to what you were asking. Sorry about that.

Andre is right. His suggestion will work best. You'll be wanting to add 
a texture map though so it gets more complicated than what a constant 
shader will likely provide.  Here is one way to implement what he 
suggests. The incidence gain will provide some control over the 
softness/hardness of the terminator. Use the Mix2Colors1 to control the 
balance of the dark side of the planet, use the Mix2Color and the 
Phong's specular decay to control the bright side of the planet. 
Specularity get's tough under this model.

Alternatively, I typically just use a phong, lower the specular real 
low,  and drop the specular decay to something like .5 and use some 
Mix2Color nodes between the texture and the ambient,diffuse and specular 
inputs to control the lighting balance. You get similar results to the 
incidence shader example, but you won't give much control over the 
softness of the terminator.


CreatePrim("Sphere", "NurbsSurface", null, null);
ApplyShader(null, "", null, "", siLetLocalMaterialsOverlap);
SelectObj("light", null, null);
ToggleVisibility(null, null, null);
SelectObj("sphere", null, true);
CopyPaste(null, "Shaders\\Texture\\Surface\\Incidence.Preset", 
"TransientObjectContainer", null);
CopyPaste(null, "Shaders\\Texture\\Mixers\\Mix_2colors.Preset", 
"TransientObjectContainer", null);
SIConnectShaderToCnxPoint("TransientObjectContainer.Incidence", 
"TransientObjectContainer.Mix_2colors.base_color", false);
SIConnectShaderToCnxPoint("Sources.Materials.DefaultLib.Material.Phong", 
"TransientObjectContainer.Mix_2colors.color1", false);
SIApplyShaderToCnxPoint("Image", 
"Sources.Materials.DefaultLib.Material.Phong.diffuse", null, null);
CopyPaste(null, "Shaders\\Texture\\Mixers\\Mix_2colors.Preset", 
"TransientObjectContainer", null);
SIConnectShaderToCnxPoint("Sources.Materials.DefaultLib.Material.Phong.Image", 
"TransientObjectContainer.Mix_2colors1.base_color", false);
SIConnectShaderToCnxPoint("TransientObjectContainer.Mix_2colors1", 
"Sources.Materials.DefaultLib.Material.Phong.ambient", false);
SIConnectShaderToCnxPoint("TransientObjectContainer.Mix_2colors", 
"Sources.Materials.DefaultLib.Material.surface", false);
SIConnectShaderToCnxPoint("Sources.Materials.DefaultLib.Material.Mix_2colors", 
"Sources.Materials.DefaultLib.Material.shadow", false);
SIConnectShaderToCnxPoint("Sources.Materials.DefaultLib.Material.Mix_2colors", 
"Sources.Materials.DefaultLib.Material.Photon", false);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.color1.red", 
0, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.color1.green", 
0, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.color1.red", 
0, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.color1.green", 
0, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.color1.blue", 
0, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Scalar2color.Incidence.mode", 
9, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.806, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.806, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.987, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.987, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.green", 
0.987, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.529, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.497, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.432, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.4, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.129, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.129, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.258, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.258, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.green", 
0.258, null);
Undo();
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.weight1.red", 
0.684, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.weight1.blue", 
0.697, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.weight1.red", 
0.716, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.weight1.blue", 
0.716, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.weight1.red", 
0.748, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.weight1.blue", 
0.748, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.weight1.red", 
0.781, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.weight1.blue", 
0.781, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.Mix_2colors1.weight1.green", 
0.781, null);
CreateProjection("sphere", siTxtUV, siTxtDefaultPlanarXY, "", 
"Texture_Projection", null, null, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.shiny", 
0, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.shiny", 
8, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.red", 
0.877, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.blue", 
0.871, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.red", 
0.548, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.blue", 
0.548, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.red", 
0.542, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.blue", 
0.542, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.green", 
0.542, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.red", 
0.484, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.blue", 
0.484, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.red", 
0.426, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.blue", 
0.426, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.red", 
0.419, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.blue", 
0.419, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Phong.specular.green", 
0.419, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.219, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.219, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.green", 
0.219, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.271, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.271, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.342, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.342, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.green", 
0.342, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.574, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.581, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.677, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.677, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.green", 
0.677, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.865, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.871, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.871, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.871, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.green", 
0.871, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.826, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.806, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.red", 
0.781, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.blue", 
0.781, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.weight1.green", 
0.781, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Scalar2color.Incidence.bias", 
0.911, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Scalar2color.Incidence.gain", 
0.034, null);
SetValue("Sources.Materials.DefaultLib.Material.Mix_2colors.Scalar2color.Incidence.gain", 
0.084, null);



Joey Ponthieux
NCI Information Systems Inc.
NASA Langley research Center
____________________________________________________________
Opinions stated here-in are strictly those of the author and
do not represent the opinions of NASA or any other party.



André Adam wrote:
> You could use an Incidence Node switched to Surface/Light mode and 
> multiply that on top of an unlit (eg constant shader) surface. It 
> offers Gain and Bias controls. Not ideal, but might work for your 
> scenario...
>
>    -André
>
>
> Adrian Lopez wrote:
> > Folks,
> >
> > How does one control the softness of the Terminator on a sphere or 
> > planet?  For those who dont know the term, the terminator is the 
> > boundary between light and dark - or day and night.  In other 
> > packages, there's a setting to control how soft or sharp this 
> > terminator is on an object - I dont see anything similar in XSI..  Am 
> > I missing something?
> >
> >
> > --
> > Adrian Lopez
> > CEO | Director | Producer
> > Liquid Light Digital
> > Kingston, Jamaica
> > C:  876.381.2471
> > W: 876.978.6418
> >
> > www.liquidlightdigital.com <http://www.liquidlightdigital.com>
> >
> > HD/SD Production | VFX & Animation | Production Management 
>
> ---
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