Planet Glow

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Planet Glow

While working on a project that includes an earth like planet viewed from space, I found out that there are no simple way to get nice halo effect around the planet using whatever tools are available in A:M. So I programmed a hack. The idea is shade transparency onto a halo sphere according to the apparent thickness of the sphere and according to an inside sphere that would be the planet. The shader must be applied to a sphere with a particular material applied to and constrained to orient like the sun. The new shader does not require to add an atmosphere layer to the model. The halo and the atmosphere are all included in the same plugin.

Here is the Planet Glow plugin (for A:M v8.5 and for Windows). Drop it into the A:M Shader folder.

And because the shader is not trivial to use, I also include the zipped project file that produced the image above. Oh! And the stars background is produced with my Worley material plugin.

Here are the parameters to set within this plugin:
High Color sets the halo color at high altitude;
Low Color sets the halo color at low altitude (near the surface of the planet;
Falloff is set to the size of the inside planet relative to the glow sphere in percent;
Glow will amplify the intensity of the glow effect;
Fade will increase the fading of the glow as the altitude gets higher (rarefaction of the atmosphere);
Transparency will adjust the atmospheric effect over the planet. The atmospheric effect color is controlled by the color attribute of the material.

More instructions:
The plugin must be used with a material as supplied in the project file and applied on the attributes of the material.
When dropped in choreography, the halo model must be set so that "Cast reflection", "Cast shadow" and "Receive shadow" are unchecked.

NOTE: The plugin does not work well with antialiasing. I don't know why but if the antialiasing is turned on, the renderer tends to render the splines inside the halo and the transparency is crapped.

One last word of caution, To get better fitting sphere one inside the other, it is better to use high resolution sphere (high patch counts) of 16 cross sections minimum. Lower resolution sphere does not produce round sphere and the glow effect is difficult to fit (same problem if you want to add a moving cloud sphere over the planet BTW).