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Overview

The MEL Scripts group of attributes provides

the ability to execute MEL scripts at certain

stages during the rendering process. This opens up the possibility of doing whatever tweaks required

at these stages. Since

3Delight comes with a set of MEL bindings for the RenderMan standard, it also becomes possible to insert RenderMan commands anywhere during rendering (see

MEL RenderMan Binding

).

 This is the equivalent of

“RIB Boxes” in other

softwares but with the added flexibility of a scripting language. In addition to

insert points listed here, there are others available in

Geometry Attribute Nodes (see

Geometry MEL Scripts) and in the Light Attribute Nodes (see Light MEL Scripts).

The

variable 'string $render_pass' is automatically defined in the context of these scripts

and is assigned the current

Render Pass node name.

Image RemovedImage AddedFigure 3.60:

The MEL Scripts group

  panel

‘Pre Render MEL’ ‘
Post Render MEL’

Specify scripts to run before the rendering starts and after the rendering is finished, respectively. Those scripts are guaranteed to run first and last. They are also executed outside of any RiBegin/RiEnd block, so these scripts are not appropriate for invoking RenderMan commands.

‘Pre Frame MEL’ ‘
Post Frame MEL’

Specify scripts to run before and after each frame, respectively. These two scripts are the very first and last things executed for each frame; they are called even before and after the RiBegin/RiEnd block, so these scripts are not appropriate for invoking RenderMan commands.

‘Post Option MEL’

Specifies a script to execute after all RenderMan options have been issued, but before the camera transforms. This can be used to override any

options.

‘Pre World MEL’

Specifies a script to execute just before RiWorldBegin which is also right after where the camera transforms are issued.

‘Post World MEL’

Specifies a script to execute right after RiWorldEnd (but before RiFrameEnd).