Overriding SPDL defaults

In the old days, if you didn’t like some default shader parameter setting, you had to edit a SPDL file and generate a new preset. As of 2011, you can use the ObjectModel (OM) to dynamically update the shader definition.

For example, if you run this Python snippet in the script editor, then the next time you create an Environment shader, it will have some different defaults:

  • Environment Mode will default to Cylinder
  • Transformation will have a connection icon
  • Background Intensity will default to 0.5
from siutils import si		# Application
from siutils import log		# LogMessage
from siutils import disp	# win32com.client.Dispatch
from siutils import C		# win32com.client.constants

# Get ShaderDef for the Environment shader
sProgID = "Softimage.sib_environment.1.0"
oDef = si.GetShaderDef( "Softimage.sib_environment.1.0" )

# Get ShaderParamDef for the Tranformation parameter
oTransform = oDef.InputParamDefs.GetParamDefByName( "transform" )

# Make it texturable so it has a connection icon
oTransform.Texturable = True

# Make Cylinder the default Environment mode
oParam = oDef.InputParamDefs.GetParamDefByName( "mode" )
oParam.DefaultValue = 1

# Change the default background intensity to 0.5
oParam = oDef.InputParamDefs.GetParamDefByName( "background_intensity" )
oParam.DefaultValue = 0.5

So, that’s how you update a shader definition. Now, all you have to do is stick that code into a siOnCreateShaderDef event plugin, and every time you create an Environment shader, it will have the defaults you want

import win32com.client
from win32com.client import constants

null = None
false = 0
true = 1

def XSILoadPlugin( in_reg ):
	in_reg.Author = "blairs"
	in_reg.Name = "ShaderDef Plug-in"
	in_reg.Major = 1
	in_reg.Minor = 0


	return true

def XSIUnloadPlugin( in_reg ):
	strPluginName = in_reg.Name
	return true

# Callback for the CreateShaderDef event.
def CreateShaderDef_OnEvent( in_ctxt ):
	oDef = in_ctxt.GetAttribute("ShaderDef")
	sProgID = str(in_ctxt.GetAttribute("ProgID"))
	if "Softimage.sib_environment.1.0" in sProgID:
		oDef.InputParamDefs.GetParamDefByName( "transform" ).Texturable = True

# 	Return value is ignored as this event can not be aborted.
	return true

Tip: Use the SDK Explorer (CTRL+SHIFT+4) to get the ProgID of a shader.