If you try to save out the file, the output node will error.Īt the top of the USD ROP LOP node’s parameters list, click Save to Disk to save your USD file to disk. To test this, bypass the Configure Layer LOP node just above the ROP Output LOP node. This makes the ROP Output LOP node issue an error when any of your layers are not configured as LOPs will not know where to save your data. Look in the Extra Files section of the parameters and notice the option for Error Saving Layers with Implicit Paths. This control allows you to work with a file structure you are familiar with, while letting LOPs create USD-friendly paths under the hood. The files for this tutorial live in USD/extras/usd/tutorials/Houdini. This is actually a very complex part of USD (also known as relative paths) and a real cause of confusion for many new users. This documentation remains for historical reference. The USD ROP LOP node examines your network for references to $HIP and replaces them with relative references when it writes out the USD file. This is what allows you to use $HIP everywhere in this LOP network. Look in the Output Processing section of the parameters and make sure that the Use Relative Paths parameter is turned on.

Select the USD ROP LOP node and then in the Parameter Editor, type the output path for the USD file in the Output File parameter field. Step 6 - Choose the default variant and save your USD

Notice how much more compact the USD code is.Īll you are doing here is adding a few lines to hide the lids to create the variant instead of adding the whole barrel again and then just hiding the lids. RMB-click on the variantblock_end node and select LOP Actions ▸ Inspect Active Layer from the context-sensitive menu that appears.Ĭompare this USD code to the USD code you created in prior steps. The second input for the variantblock_end node uses the Prune LOP to prune the lid from the barrel by making it inactive. The first input for the variantblock_end node comes in unmodified. Your /stage network should now look like the image below. Select the Prune LOP node, and then LMB-drag Lids from the Scene Graph Tree to the Primitive Path parameter field in the Parameter Editor.Ĭonnect the output of the variantblock_begin node to the both the input of the Lid node and the input of the Prune LOP node.Ĭonnect the output of the Prune LOP node to the input on the No_Lid node.Ĭonnect the output of the Lid node to the second input on the variantblock_end node.Ĭonnect the output of the No_Lid node to second input on the variantblock_end node.Ĭonnect the output of the Barrel_w_Lid node to the input on the variantblock_begin node.Ĭonnect the output of the Barrel_w_Lid node to the first input on the variantblock_end node. If you don’t want the hassle of pinning the pane and dragging and dropping, then go to the Scene Graph Tree, select the path you want, RMB-click ▸ Copy Path, and then paste the path in the Primitive Path parameter field.įor more information on targeting primitive patterns, please see the Primitive Matching Patterns help page.Ĭreate a Null LOP node, add it to the block, and then rename it to Lid.Ĭreate a Null LOP node, add it to the block, and then rename it to No_Lid.Ĭreate a Prune LOP node and add it to the block.

Houdini solaris tutorial