I’ve read the documentation but it is unclear if there is any way to set the pentelty based on what material is at that point. In my game different surfaces have different speeds for movement over them and this can change as the game runs.
Currently there is no way to do this directly.
You can however use a texture to paint the penalty, which might be useful: https://arongranberg.com/astar/docs/class_pathfinding_1_1_grid_graph.php#ac855bb1ba0ecd663efca9bda41527a6c
(in the pro version it is available under the ‘Extra’ foldout in the grid graph settings).
I will move this thread to the ‘Feature Requests’ category.