TYPE: ROP
TITLE: Wren ROP

This output operator is used to drive the Wren rendering program. The operator
sets up all necessary options and then invokes the renderer. Alternatively, the
output can be saved to disk as a script file to be rendered later.

When rendering postscript, the width and height of the image represent
the width and height of the "paper" (in inches).  Thus to render
landscape mode, the width should be set to 11 and the height set to 8.5.
The postscript options can be set by clicking the + button beside the
render command.

Arguments may be passed to the script and variable expansion is done before
calling the script.

Parameters:

    Render               - Begins the render.
    Camera               - Which camera to render the scene from.
    Visible Objects      - List of objects visible in the rendered scene.
    Unload SOPs          - Unload SOP geometry after used by the render
    Use Display SOP      - Use the display (instead of render) SOP.
    Output Picture       - Where the output of the render should be directed.
    Frame Range          - Allows specification of a range of frames to render.
    Start/End/Inc        - Specifies the first & last frames and the increment.
                           Note that when rendering a sequence of images with a
                           fraction Inc, $N is the number of the frame rendered,
                           $F is the nearest integer frame number, $FF is the 
                           floating point frame number
    Initialize Simulation SOPs - force all simulation SOPs to be reset.
    Generate Script File - Outputs the renderer's script file instead of
                           feeding the data to the renderer directly.
    Binary Script File   - Toggles between ascii and binary file formats.
    Script File          - Filename of the script file to create.
    Render Command       - The command used to invoke the renderer.  Can be
                           modified with the popup window.
    Render in Background - Continue to use Houdini while rendering
    Super Sample         - Number of rays sent per pixel in x and y when
                           antialiasing.
    Override Camera Res  - Allows specification of the render resolution.
    Resolution           - Resolution to render at.
    Pixel Aspect         - Specifies pixel aspect ratio of the intended
                           viewing device.
    Jitter               - Limits the amount of jitter.  0 = no jitter.
    Pre-Render Script    - Execute this script before any rendering.
    Pre-Frame Script     - Execute this script before each frame
    Post-Frame Script    - Execute this script after each frame
    Post-Render Script   - Execute this script after all rendering

Local Variables:
    N        - The current frame of the range specified.  This always
               starts at 1.
    NRENDER  - Total number of frames being rendered.
