This is RenderMan 21 Documentation you are viewing. The Rmanwiki home page will redirect you to the current documentation.
Imagine that you want to give your artists some function in "it" that they are going to perform many times, over and over again, repeatedly, but they're not keen on using typed commands and can't remember them anyway, what with being so busy making their art. Luckily for you, "it" has a customizable Commands menu that can be used for just this situation.
This tutorial is going to build on the ice.extensions.falsecolor command available in the "it" console, providing a simple UI that makes it easier to control.
If you are not familiar with existing "it" console command ice.extensions.falsecolor, bring up the "it" console window and print out its usage by typing:
You should see something like this:
falsecolor can operate on any image; open an image and try running it by typing in the console:
This might not be terribly useful, but there was a very specific situation that falsecolor was created for: to make sense of the cpuTime AOV. If you view the AOV in "it", you'll see something like this:
Applying the falsecolor command will give us something much more visual:
blue is lower CPU time values and red is higher.
Create a Command Extension File
The "it" commands are stored in files that are loaded by the usual LoadExtension command from an .ini file. As always, we discourage editing the factory shipped .ini files and, instead, recommend setting the environment variable RMS_SCRIPT_PATHS to point to directories where you put your own, site-specific .ini files.
So, quit "it", make sure the aforementioned variable is set, then add the following line to your local it.ini file:
This tells it to load a file containing an "it" custom command from that file. And in that file, put the following:
If you open "it" now you should see the logging messages we added to your it.ini file, and in the Commands/CustomCmds menu you'll see a False Color option. Open or render an image with a CPUtime AOV and you can now select the new command.
If you do not specify a path to your extension file on the LoadExtension line, "it" will automatically look in the same directory where the it.ini file exists for your extension file.
Let's take a closer look at falsecolor.py to see what it is doing. If you have experience in programming with Python, this should all look familiar to you.
This imports both the 'it' and 'ice' modules, which gives us access to both "it" and IceMan scripting functions.
This declares a new class 'FalseColorCommand' for our custom command. Note that all "it" custom commands must be a subclass of 'It3Command'.
This is the __init__ constructor method for our new class. The m_menuPath defines where to place our custom command in the "it" menu.
This is the Invoke method for our class, which is the meat of our custom command. This method will be called when our custom command is executed. The first line of our method retrieves the current image element in our "it" catalog. The second line retrieves the ice.Image instance for the image elements. Finally, the last line calls the falsecolor command passing in the name of the AOV to search for (CPU) and the ice.Image instance.
This tells the "it" application about the new command. The python list it.commands sets the contents and the order of the Commands menu. Note that you add the python class, in this case FalseColorCommand, not an instance of the class to the list.
Add a Dialog to the Command
ice.extensions.falsecolor takes a couple of options - w and m - which control what range of hue to scale the input to. Since a hue value isn't very meaningful or easy to remember, we'll make a dialog for the user to pick from a few color schemes where we have pre-selected the values for the hue range.
As "it" is now built with the Qt framework, users can also use Qt to create their own dialogs.
Update falsecolor.py with the example below and restart "it".
Once you've restarted "it", load your image with a CPUtime AOV and run the command again. This time you should see our new dialog:
Going through the changes one at a time:
Here, we are importing a couple more modules, necessary to create our dialog.
We've modified our __init__ constructor to add a couple of more member variables. Adding these will make it easier to share data between methods that need it. m_dlg holds our dialog instance that will be created in the makeUI method (see below). The third line allows us to add standard Close and Apply buttons to our dialog. m_colorSelected is the current selected color. m_wList and mList are lists of available values for the hues.
Here, we've moved the original code in the Invoke method to a new apply method. The Invoke method has been changed to call makeUI, which will create the Dialog instance. The instance is then saved to m_dlg. Once we have are instance we display the dialog to the screen. We use the m_colorSelected variable to select which values we want from the m_wList and m_mList.
The makeUI method is where our dialog window is created. Programming with Qt to create a UI is beyond the scope of this documentation, but, essentially, a dialog is created with the CreateDialog method. We then add layouts to the dialog, followed by a label describing the option, and a QComboBox that will present a dropdown menu for the user to select the color option they would like to use. The QComboBox is connected to our currentIndexChanged method so that whenever the current selection is changed, the new index is passed to the currentIndexChanged method where we can update our m_colorSelected memeber variable. Finally, we retrieve the standard Apply button from our dialog and connect our apply method, so that it is called whenever the button is pressed.