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RenderMan for Maya will search in the following order and merge/override in the same order. Note : This hierarchical process is valid for the other config files: shelf.json, aovs.json, menu.json, etc.

1. rfm will read RFMTREE/config/rfm.json. This is the base configuration and should NEVER be altered by you, please make a custom version.
2. rfm looks for RFM_SITE_PATH and RFM_SHOW_PATH. These can either be environment variables or values in the main rfm.json (prefer the Environment Variable route).
3. rfm looks for RFMfor RFM_SITE_PATH/config/rfm.json. if found, it's its contents will be merged with the base config.
4. rfm looks for RFMfor RFM_SHOW_PATH/config/rfm.json. if found, it's its contents will be merged/override the base config and the site config.
5. rfm looks for ~for ~/rfm/config/rfm.json. if found, it's its contents will be merged/override the base config, the site and show config. On Windows this would be Documents\config\rfm.json.

override.json can be used to override default values of RfM nodes both standard and custom.

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shader PxrLayer
   [[int rfm_nodeid=1053299, string 
rfm_classification="rendernode/RenderMan/pattern",        
    int rfc_nodeid=1037674, string rfc_description="Xpxrlayer",         
    string help = "An OSL pattern for layerable parameters for PxrSurface or "
            "input layer to PxrLayerMixer."
   ]]

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C++ Plug-ins

In your custom rfm.json file, you can load your files like the below example:

{
    "$schema": "./rfmSchema.json",
    "resources": {
        "user": {
            "nodes": {
                "node_exclusion_list": [
                    "PxrHair",
                    "PxrLMDiffuse",
                    "PxrLMGlass",
                    "PxrLMMetal",
                    "PxrLMPlastic",
                    "PxrLMSubsurface",
                    "PxrSkin",
                    "PxrValidateBxdf"
                ]
            }
        }
    },
    "dirmaps": {
        "user_to_z": {
            "from": "/User/name/maya",
            "to": "Z:/maya",
            "zone": "UNC"
        }
    }
}

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Node IDs for these are included in the .args file. The order doesn't matter but it must be in the first level of the tags. The below example is for a light.

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