Geometry shaders are applied to geometry shader objects, which are special objects that have a GeoShader property. The GeoShader property lists the geometry shaders that are attached to the null and allows you to access and modify their parameters.
Applying a geometry shader is a three-step process:
1. Get a geometry shader primitive.
2. Add geometry shaders to the GeoShader property as needed.
3. Edit the geometry shaders’ parameters to achieve the desired effect.
To open the GeoShader property editor
Once you have a geometry shader object in your scene, you can open the GeoShader property editor at any time by clicking on the icon for either the GeoShader object or property in an explorer. Alternatively, you can select the object (represented by a randomized wireframe cube) in a 3D view and press Enter.
Getting Geometry Shader Objects
A geometry shader object is a placeholder in your scene for the geometry that will be created by your shader in mental ray.
To get a geometry shader object
• Choose Get > Primitive > Geometry Shader Primitive from any toolbar. The GeoShader property editor opens.
The Shader list is initially blank. You can add geometry shaders as described in the next section.
By itself, the geometry shader object does not create any geometry. You must apply a geometry shader that does create the geometry for rendering.
You can add multiple geometry shaders to the same object.
To add a geometry shader
1. In the GeoShader property editor, click Add.
2. Use the browser that opens to locate and select a geometry shader, then click OK. The geometry shader is added to the Shader list.
Modifying Geometry Shader Parameters
You can control a geometry shader by modifying its parameters. The available parameters depend on what was programmed for the shader.
To modify geometry shader parameters
1. In the GeoShader property editor, select a shader from the Shader list.
2. Click Inspect. The property editor for the geometry shader opens.
3. Modify the parameters as desired.
You can remove a geometry shader that you have previously applied to a geometry shader object, for example, if you decide you want to use a different shader.
Removing the shader does not remove the object placeholder in the scene.
To remove a geometry shader
1. In the GeoShader property editor, select a shader from the Shader list.
2. Click Delete.
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