The Light Attribute Node is used to specify parameters that are not contained in the light shader. For instance, several light shaders can use shadow maps; the Light Attribute Node can be used to generate these shadow maps. When there are no light attribute node attached to a light, 3Delight for Maya will do its best to extract relevant parameters from the Maya light node.
Light Attribute nodes are created empty. Attributes can be added and removed by using the Add / Remove Attributes button. Left-click on this button brings up the Add / Remove Attributes Window, which is better suited for multiple attribute addition or removal (see The Add / Remove Attributes Window). Right-click on the Add / Remove Attributes button offers the same functionality through popup menus, which are more convenient when only one attribute or attribute group needs to be added or removed.
Motion Blur
The Transformation Blur attribute controls if the camera used for rendering the shadow map will have transformation blur applied to it or not. This camera is either explicitly specified, or it is derived from the attached light’s position and orientation (see [shadow camera attribute], page 50). Note that this attribute is ignored unless the "Generate With Motion Blur" attribute is turned on (see [generate with motion blur attribute], page 50). The available options are detailed below.
| Value | Description |
|---|---|
| Off | No transformation blur will be applied to the shadow map camera, regardless of the render pass current Transformation Blur settings. This is the default. |
| On | Transformation blur will be applied to the shadow map camera, even if the Transformation Blur attribute is turned off in the render pass. The number of samples is determined by the "Trans- formation Samples" of the render pass. This value has no effect if "Generate With Motion Blur" is turned off. |
| Inherit | Transformation blur will be applied to the shadow map camera according to the Transformation Blur attribute of the render pass. The number of samples is determined by the "Transformation Sam- ples" of the render pass. This value has no effect if "Generate With Motion Blur" is turned off. |
Area Light
Samples
This attribute sets the number of samples to use when sampling the area light. Larger values take longer to render but give smoother results. The default is 16. This attribute has no effect if the attached light shape is not an area light.
Sampling Strategy
This attribute controls how the attached area lights are rendered.
| Value | Description |
|---|---|
| Faster | In this mode, specular highlights will not follow the shape of the area light , only shadows will be rendered correctly. |
| Better | In this mode, both the specular highlights and the shadows are rendered correctly. This setting is recommended when accurate specular highlights are important. |
MEL Scripts
3Delight For Maya lets you run MEL scripts before and after each shadow map.
Pre Render MEL
This attribute specify a MEL script that will be executed before the shadow map is rendered. More precisely, the script will be executed just before the FrameBegin RIB statement of the shadow map. This attribute is empty by default.
Post Render MEL
This attribute specify a MEL script that will be executed after the shadow map is rendered. More precisely, the script will be executed just after the FrameEnd RIB statement of the shadow map. This attribute is empty by default.
Two variables are automatically defined in the execution scripts execution as show in the following table.
| Variable | Description |
|---|---|
string $shape_path | Contains the current light shape path. |
string $attribs_node | Contains the current light attribute node name. |