- Right-click on your terrain and select Navigation/Add Path Area. Path Area will be added to currently selected layer and purple cuboid will appear in world window (if not see Note 1).
- Enlarge your path area by clicking and moving one of the axes. Make it big enough so NPCs can move around easily. Don't make it too small or short.
- Move Path Area down so the small part of path area should be under the "ground" level.
- Go to Tools/Navigation Mesh. Select your Path Area.
- In Generation section select Process all loaded areas. Click on Collect geometry, then Generate navigation mesh and Filter Mesh. If you have dynamic actions like climb point you'll want to click on Preprocess dynamic data too.
Notes
1. In View/Filters_debug options from the upper menu (or press Ctrl+Alt+F), subtree Editor options/Debug you have to check Areas and Walkmesh to actually see them in the Editor.2. Click on the "Play Game on current layers only. Fast." game pad to boot the game. Geralt should spawn in the exact place where the camera was set. If Geralt spawns in the corner of the map (0,0), bring the camera much closer to the ground.
3. If the navigation still does not work when it should, open View/Filters and activate collision. Some objects may have invisible collisions disrupting your walkmesh.
4. Make sure that your Path Areas don't touch any water meshes, else it will cause REDkit to crash when collecting Terrain Geometry.