Terrain
bCastDynamicShadow
This flag should be OFF. Setting this flag to ON will cast dynamic preshadows by the terrain for both per-object shadows and whole scene dynamic shadows, which can be very expensive depending on the number of dynamic primitives in the scene. Preshadows (which are dynamic shadows from the static environment onto dynamic objects) only make sense if the terrain has hills and valleys throughout the scene. If the scene just has a few mounds here and there it might be worth modeling the mounds with static meshes and have the terrain blend in at the bottom. The side effect of disabling bCastDynamicShadow is that terrain deco layers (e.g. grass) will not cast whole scene dynamic shadows. But considering that shadows from deco layers usually are low-res and don't look great, it is a good price to pay for a substantial performance boost.
Terrain Layers
The RO2 engine allows for a maximum of 12 textures to be blended for terrain. These 12 textures could be part of 2 terrain layers (6 textures each), 3 terrain layers (4 textures each), or any other combination thereof. This is a hard limit for the engine, and exceeding this limit will result in rainbow colored terrain patches. However, fetching and accessing so many textures is not cheap and since the terrain usually takes up a large portion of the screen, it is recommended that you keep the number of blend textures to a minimum.
One example for this is that say you have a terrain which comprises or dirt, rubble and snow and one part of the terrain is solid concrete. Instead of making 4 terrain layers of dirt, rubble, snow and concrete and blending between them it is more optimized if the terrain uses 3 layers of dirt, rubble and snow, and the concrete portion is modeled separately as BSP, static mesh or even another terrain actor. Doing this will reduce the overall cost of rendering the entire terrain since the concrete layer texture fetches are eliminated for the rest of the terrain that doesn't need it.
Static Meshes
bCastDynamicShadow
When placing a static mesh in the level, you should decide whether you want it to cast dynamic preshadows or not. Preshadows are dynamic shadows from the static environment onto dynamic objects, and can be very expensive depending on the number of dynamic primitives in the scene. Turning off this flag for a lot of static meshes in the environment in the scene such as debris, rubble, etc. will improve the dynamic shadow performance.
Distance Culling
Using distance culling effectively will allow you to have a lot of detail in your environment whilst still allowing the map to perform well. There are 2 ways to do this :
You want as few drawcalls as possible in any given scene targeting around 2000 max if at all possible. So if you find you are over this limit you will need to be more aggressive in your culling.
Materials
Using Material LODs
In order to make the best looking environment materials as well as keep the overall performance cost low, consider using material LODs. The concept is very simple - assign the best looking/highest instruction count material to the base LOD for a static mesh, and then create another LOD for the static mesh (this can have the exact same triangle count as the base LOD) and assign it a simple material that does not have expensive operations such as depth biased alpha, specularity, cube maps or even normal maps. Such subtle lighting effects cannot be perceived from a distance anyway, and will make improve the fill rate for the rendered scene.
bCastDynamicShadow
This flag should be OFF. Setting this flag to ON will cast dynamic preshadows by the terrain for both per-object shadows and whole scene dynamic shadows, which can be very expensive depending on the number of dynamic primitives in the scene. Preshadows (which are dynamic shadows from the static environment onto dynamic objects) only make sense if the terrain has hills and valleys throughout the scene. If the scene just has a few mounds here and there it might be worth modeling the mounds with static meshes and have the terrain blend in at the bottom. The side effect of disabling bCastDynamicShadow is that terrain deco layers (e.g. grass) will not cast whole scene dynamic shadows. But considering that shadows from deco layers usually are low-res and don't look great, it is a good price to pay for a substantial performance boost.
Terrain Layers
The RO2 engine allows for a maximum of 12 textures to be blended for terrain. These 12 textures could be part of 2 terrain layers (6 textures each), 3 terrain layers (4 textures each), or any other combination thereof. This is a hard limit for the engine, and exceeding this limit will result in rainbow colored terrain patches. However, fetching and accessing so many textures is not cheap and since the terrain usually takes up a large portion of the screen, it is recommended that you keep the number of blend textures to a minimum.
One example for this is that say you have a terrain which comprises or dirt, rubble and snow and one part of the terrain is solid concrete. Instead of making 4 terrain layers of dirt, rubble, snow and concrete and blending between them it is more optimized if the terrain uses 3 layers of dirt, rubble and snow, and the concrete portion is modeled separately as BSP, static mesh or even another terrain actor. Doing this will reduce the overall cost of rendering the entire terrain since the concrete layer texture fetches are eliminated for the rest of the terrain that doesn't need it.
Static Meshes
bCastDynamicShadow
When placing a static mesh in the level, you should decide whether you want it to cast dynamic preshadows or not. Preshadows are dynamic shadows from the static environment onto dynamic objects, and can be very expensive depending on the number of dynamic primitives in the scene. Turning off this flag for a lot of static meshes in the environment in the scene such as debris, rubble, etc. will improve the dynamic shadow performance.
Distance Culling
Using distance culling effectively will allow you to have a lot of detail in your environment whilst still allowing the map to perform well. There are 2 ways to do this :
- You can either put a CullDistanceVolume around the map and the let the map build process choose the appropriate cull distances for the placed static meshes in the level. This method is not ideal though, and might cause certain cover objects, etc. to disappear at a distance (which is not desirable).
- Or, you can manually set the MaxDrawDistance for each object.
You want as few drawcalls as possible in any given scene targeting around 2000 max if at all possible. So if you find you are over this limit you will need to be more aggressive in your culling.
Materials
Using Material LODs
In order to make the best looking environment materials as well as keep the overall performance cost low, consider using material LODs. The concept is very simple - assign the best looking/highest instruction count material to the base LOD for a static mesh, and then create another LOD for the static mesh (this can have the exact same triangle count as the base LOD) and assign it a simple material that does not have expensive operations such as depth biased alpha, specularity, cube maps or even normal maps. Such subtle lighting effects cannot be perceived from a distance anyway, and will make improve the fill rate for the rendered scene.
