rdMeshTools Tutorial 8 – Creating new meshes for negatively scale actors

When using InstancedStaticMeshes with rdInst’s managed instances, there are issues with negatively scaled meshes. There is an option in the StaticMesh Component (ISMCs and HISMCs derive from them) to cater for this called “ReverseCulling” which changes the backface culling to the other way around, but this has to be done on a new component for the mesh so there are multiple draw calls and it leads to slower referencing and look-ups on instances when using them dynamically – including in the editor.

rdInst 1.40 has an auto-instancing system for static actors in your levels which handles negatively scaled meshes and meshes with unique materials – this is for meshes you’ll be wanting to use dynamically – in prefabs, spawn actors and proxies.

This is where this tool comes in handy – it creates (or finds) new meshes that are mirrored in the axis that are negative, and replaces the actors in the level (selection only) with the newly created ones.

The tutorial uses one the Houses from the Residential Houses 2 pack from PropHaus – any meshes can be used.

Step 1. Add the meshes to your level (including negatively scaled meshes)

The first step is to add your assets to the level, here we copy the BPP_House02 house from the Residential Houses pack into the level and then “Replace in level” with rdBPtools to convert it to StaticMesh Actors.

You can find the negatively scaled actors by selecting all the actors in the building, then using the rdMeshTools “Refine Selection” tool in the Context menu – refine to just negatively scaled assets:

This refines it to 6 actors, all but one are gutter caps:

Step 2. Use the Fix Negative Scaled Meshes Tool

Now just right-click on one of the selection (retaining the selection) and choose the “Fix negatively scaled meshes”

It then creates the new meshes, replacing the existing negative ones and displays a summary once complete.

Step 3. Done

That’s it – just save the level to keep your changes.