SkyrimSE:Grass LOD Guide

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Skyrim Special Edition Grass LOD Guide

A guide to grass LOD for Skyrim Special Edition

by: The Step Team  | Forum Topic

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WIP

This guide is under construction and is incomplete.

Guide scope[edit]

This guide intends to explain the process by which grass LOD can be generated via the grass cache files for Skyrim Special Edition. It may include some general recommendations for optimizing appearance and performance, as well as technical information that may prove useful for troubleshooting. A quick start guide is included to generally guide users through this process.

Quick start[edit]

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WIP:
Incomplete

This is meant to give a simple walkthrough of setting up grass LOD. It provides a suggested configuration for use with the STEP guide for Skyrim Special Edition that renders full grass only up to the uGridsToLoad distance (the fully loaded portion around the player character) with grass LOD stretching out from there up to the LOD 4 distance (controlled by fBlockLevel0Distance:TerrainManager INI setting). The grass LOD is very performance intensive, and may carry as much as a 20fps penalty, so users on weaker systems may wish to not use the DynDOLOD portion of this walkthrough.

Relevant recommended settings for SkyrimPrefs.ini:

[Grass]
fGrassMaxStartFadeDistance=8192
fGrassMinStartFadeDistance=0
fGrassStartFadeDistance=6144

[TerrainManager]
fBlockLevel0Distance=53248
fBlockLevel1Distance=159744
fBlockMaximumDistance=331776
fSplitDistanceMult=1.000

Step 1: Install required mods[edit]

The following mods must be installed and setup correctly to use this quick start walkthrough:

Step 2: Generate a list of worldspaces containing grass[edit]

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NOTE:
If you haven't already sorted your plugins with LOOT, now would be a good time to do so.

This step is recommended to reduce the amount of worldspaces traversed by NGIO during grass cache generation.

  1. Open SSEdit and load all your plugins.
  2. Once the Background Loader: Finished message appears, right click anywhere in the left pane and select Apply Script....
  3. In the window that appears, in the Script dropdown, select List worldspaces with grass and click OK.
  4. Wait for it to finish processing. This may take a minute or two, depending on how many mods you have.
  5. When the Worldspaces with grass window appears, right-click the highlighted text and select Copy.
  6. Click OK and exit SSEdit.
  7. Open GrassControl.config.txt from NGIO (it's under Text Files in the mod information window in Mod Organizer) and paste the contents between the quotation marks of the OnlyPregenerateWorldSpaces setting.
  8. Save GrassControl.config.txt

Step 3: Configure GrassControl.config.txt[edit]

Ensure you have the following settings in GrassControl.config.txt:

RayCast = True
SuperDenseGrass = False
ProfilerReport = False
UseGrassCache = True
ExtendGrassDistance = False
ExtendGrassCount = True
EnsureMaxGrassTypesPerTextureSetting = 15
OverwriteGrassDistance = 6144
OverwriteGrassFadeRange = 14128
OverwriteMinGrassSize = 85
GlobalGrassScale = 1.5
OnlyLoadFromCache = True
DynDOLODGrassMode = 1

Step 4: Configure the game ini files to run in a small window[edit]

Info-Logo.png
NOTE:
This step is optional but recommended. If you use SSE Display Tweaks to modify your resolution and/or screen mode, you will need to modify the equivalent settings there instead.
  1. Launch BethINI.
  2. Ensure that you have the correct INI Path in the Setup tab.
  3. Under Basic, set Resolution to 800x600.
  4. Checkmark Windowed Mode.
  5. Save and exit.

Step 5: Precache Grass[edit]

This process will take about 20 minutes to complete, but may vary depending on hardware and installed mods. The game will typically crash during grass generation. This is normal. There is no need to monitor or click 'OK' when restarts occur.

  1. Click the MO Tools button in MO, and select Precache Grass.
  2. Wait until the game displays an error message stating "Grass generation finished successfully!" Click the OK button when it appears. Also click the OK button for the duplicate message in Mod Organizer.
  3. The grass cache should have been generated within Overwrite. Right-click on Overwrite and select Create Mod....
  4. Name it "Grass Cache - cgid" or something similar and click OK.

Step 6: Configure the game ini files back to the correct resolution and screen mode[edit]

Info-Logo.png
NOTE:
This step must be completed if you followed step 4. Skip if you didn't follow step 4. If you use SSE Display Tweaks to modify your resolution and/or screen mode, you will need to modify the equivalent settings there instead.
  1. Launch BethINI.
  2. Set Resolution back to its correct resolution.
  3. If you run the game in fullscreen mode instead of borderless windowed mode, uncheck Windowed Mode.
  4. Save and exit.

Step 7: Run TexGen[edit]

  1. Run TexGen from the MO2 executable drop-down list.
  2. Ensure that you have all options checkmarked and set to the appropriate resolution. TexGen should automatically detect the correct resolution settings, so if you haven't changed them, they should be correct.
  3. Optionally tweak Direct and Ambient settings to change lighting on the generated Billboards. Default values should be used unless it is found that the billboards require additional lighting tweaks.
  4. Ensure that all texture settings are set to Default (BC7 Quick).
  5. Click Start.
  6. Once the completed message has appeared (typically 15-30 minutes, depending on the PC), click Zip & Exit.
  7. Navigate to the DynDOLOD TexGen_Output folder location (e.g. ../Modding/Tools/DynDOLOD/TexGen_Output).
  8. Drag and drop the TexGen_Outputzip.zip into Mod Organizer 2 near the bottom of the left pane to install it. Name it in a way that you can recognize to which profile it belongs. Don't forget to checkmark it.

Step 8: Configure DynDOLOD_SSE.ini[edit]

  1. Navigate to your DynDOLOD installation and open the DynDOLOD_SSE.ini file within the Edit Scripts\DynDOLOD folder.
  2. Change the following settings if you haven't already:
; set to 1 for expert LODGen options in advanced mode, disables wizard automatically
Expert=1
; grass LOD brightness multipliers
GrassBrightnessTopR=0.36
GrassBrightnessTopG=0.365
GrassBrightnessTopB=0.35
; make bottom darker to fake shadowing
GrassBrightnessBottomR=0.200
GrassBrightnessBottomG=0.203
GrassBrightnessBottomB=0.195

Step 9: Run DynDOLOD[edit]

  1. Run DynDOLOD from the MO2 executable drop-down list to open the GUI configuration in 'expert' mode (if the DynDOLOD INI modification was set as described previously).
  2. Ensure that all worldspaces are ticked.
  3. Tweak your rules and settings to your preference.
  4. Checkmark Grass LOD, set Density for grass to 35, and set Mode to 1.
  5. Once the configuration is finalized, click OK. DynDOLOD generation will start processing. This step will take some time, typically around a half hour, but may vary depending on your settings/hardware/mods.
  6. When the completed message has appeared, click Save & Zip & Exit.
  7. Navigate to the DynDOLOD DynDOLOD_Output folder location (e.g. ../Modding/Tools/DynDOLOD/DynDOLOD_Output).
  8. Drag and drop the DynDOLOD_Outputzip.zip into Mod Organizer 2 near the bottom of the left pane to install it. Name it in a way that you can recognize to which profile it belongs. Don't forget to checkmark it.

No Grass In Objects[edit]

No Grass In Objects is required to create the grass cache files necessary to generate the LOD for grass. It also can stop grass from growing inside rocks and other objects, and it can increase the grass draw distance beyond the loaded cells.

Settings[edit]

This section will cover the different settings and make suggestions on usage.

Raycasting[edit]

This feature is the original feature that made this tool popular, and it is the reason for the name of the mod. RayCast is recommended to be enabled to utilize this feature to eliminate grass being drawn through stones and other objects that it should not grow through. RayCastIgnoreForms setting can be used to exclude base forms that you want grass to still grow through.

RayCast = True
RayCastHeight = 150
RayCastDepth = 5
RayCastCollisionLayers = "1 2 13 20 31"
RayCastIgnoreForms = ""

Super dense grass[edit]

Super dense grass settings allow the game to produce significantly more grass without changing other settings. It is recommended not to use this feature if you can help it. Instead, it is recommended to decrease OverwriteMinGrassSize to produce dense grass if at all possible, or use a grass mod that is setup to allow for very dense grass in a more optimal manner.

SuperDenseGrass = False
SuperDenseMode = 8

Grass cache settings[edit]

It is recommended to use the grass cache by setting UseGrassCache to True. ProfilerReport can be used to see how much time is taken to generate the grass cache files.

ProfilerReport = False
UseGrassCache = True

Extended grass features[edit]

ExtendGrassDistance and ExtendGrassCount are to be set to true if you want to show grass beyond a uGridsToLoad of 5 (i.e., LOD grass). Otherwise, these can be set to false and vanilla limits will apply.

ExtendGrassDistance = False
ExtendGrassCount = False

Vanilla INI setting overrides[edit]

Setting any of these to -1 will revert the setting to what it is set to within the game INI files. There are many of these settings that authors like to force on the user via plugin INIs, so it is generally advised to set most of these settings here.

  • EnsureMaxGrassTypesPerTextureSetting overrides iMaxGrassTypesPerTexure:Grass in Skyrim.ini
  • OverwriteGrassDistance overrides fGrassStartFadeDistance:Grass in SkyrimPrefs.ini
  • OverwriteGrassFadeRange overrides fGrassFadeRange:Grass in Skyrim.ini
  • OverwriteMinGrassSize overrides iMinGrassSize:Grass in Skyrim.ini
EnsureMaxGrassTypesPerTextureSetting=15
OverwriteGrassDistance=6144
OverwriteGrassFadeRange=14128
OverwriteMinGrassSize=60

OnlyLoadFromCache[edit]

OnlyLoadFromCache means that the game will only display grass for which it has generated grass cache files. If you find a location that is missing grass, disabling this and loading up the location should cause the game to generate the necessary grass cache file for the location. Alternatively, if you are finding an issue with floating grass or other problems with the grass in the cell, you can delete the relevant grass cache file and regenerate it by setting this to False and loading the area. For normal gameplay, set this to True.

OnlyLoadFromCache = True

Grass cache pregeneration settings[edit]

SkipPregenerateWorldSpaces allows you to set worldspaces where it will not attempt to make grass cache files. Conversely, OnlyPregenerateWorldSpaces can be used to limit grass cache generation to a specific set of worldspaces.

SkipPregenerateWorldSpaces = "DLC2ApocryphaWorld;DLC01Boneyard;WindhelmPitWorldspace"
OnlyPregenerateWorldSpaces = ""

DynDOLODGrassMode[edit]

DynDOLODGrassMode can be used to quickly set settings to conform to the method chosen. If set to 1, OverwriteGrassDistance will be set to 999999, OverwriteGrassFadeRange will be set to 0, and ExtendGrassDistance will be set to false. If set to 2, OverwriteGrassDistance will be set to 999999, OverwriteGrassFadeRange will be set to 0, and ExtendGrassDistance will be set to true. Also, the ChosenGrassGridRadius (similar to iGrassCellRadius:Grass in Skyrim.ini) will be determined based off this value.

DynDOLODGrassMode = 1

Pregenerating the grass cache[edit]

In order to improve performance, it is highly recommended to pregenerate the grass cache. Mod Organizer users can simply use the provided plugin, which will handle this automatically. Other users will need to create a PrecacheGrass.txt file in the game directory and launch the game. Precaching can take hours in some cases, especially if using grass beyond the uGridsToLoad. Crashing during this operation is expected and normal behavior; however, if it continues to crash repeatedly at a location, a problem likely exists in the modded setup that will cause a crash at that area and the precaching process will not be able to complete. The user will have to identify and fix the problem before precaching can be successfully performed.

After the grass cache pregeneration process is finished, the game will display an error message that says the process completed successfully. Grass cache files will be created in a grass folder either in Overwrite for Mod Organizer users or in Data. Mod Organizer users can create a mod from the output and enable it to keep it organized. If, after the process is complete, there are no cache files, something likely is wrong with the settings utilized.

DynDOLOD[edit]

DynDOLOD 3 is required to generate grass billboards and grass LOD. This section will cover the different settings and make suggestions on usage.

TexGen[edit]

TexGen is included within the DynDOLOD installation and must be used to create grass LOD billboards. This can be done by simply checking the Grass in the main TexGen Options window before TexGen generation. Users can also modify the settings for "Direct" (light from the sun) and "Ambient" (general lighting) for the textures. Defaults are fine to start. Texgen grass billboards.png

DynDOLOD grass LOD settings[edit]

DynDOLOD does not generate grass LOD by default. In order to enable it, \Edit Scripts\DynDOLOD\DynDOLOD_SSE.ini must be modified. The following settings pertain to grass LOD generation:

; set to 1 to enable grass LOD for the nearest object LOD level 4, requires *.cgid grass files in data\grass\ folder from Grass Control and grass LOD billboards generated by TexGen
Grass=0

; 0 to 100%; 0 = no grass - unlike Grass=0, the grass LOD billboards will still be added to the object LOD texture atlas
GrassDensity=100

; set to 1 to flag grass LOD as LargeReference, so that it unloads at the distance of uLargeRefLODGridSize instead of the usual uGridsToLoad distance
GrassLargeReference=0

; grass LOD brightness multipliers
GrassBrightnessTopR=0.400
GrassBrightnessTopG=0.445
GrassBrightnessTopB=0.450
; make bottom darker to fake shadowing
GrassBrightnessBottomR=0.200
GrassBrightnessBottomG=0.223
GrassBrightnessBottomB=0.225

To enable grass LOD generation, set Grass=1. The grass cache pregenerated by using NGIO as explained above is necessary for DynDOLOD to know where to place grass.

GrassDensity works opposite the way OverwriteMinGrassSize (NGIO's iMinGrassSize equivalent) does to set the grass density of grass LODs. For instance, the higher OverwriteMinGrassSize is set, the less dense the grass is and the more performance friendly. Conversely, the lower GrassDensity is set, the less dense the grass LOD is and the more performance friendly. Obviously, keeping this as low as possible is best for maximizing performance. In many cases, using a setting of GrassDensity=35 is not at all too low and does not make the grass appear uneven in height.

It is recommended to leave GrassLargeReference=0. GrassLargeReference=1 should only be used if extending the full grass range through NGIO beyond the uGridsToLoad distance. As a quick setup feature, NGIO DynDOLODGrassMode setting of 2 can be used to ensure proper grass cache setup in this mode. If using NGIO DynDOLODGrassMode of 0 or 1 (with 1 being the quick setup setting), this should remain set to 0. It is much more performance friendly to only render full grass to uGridsToLoad distance, and since we will have grass in LODs, grass will still stretch as far as we can see. Therefore, it is recommended to leave GrassLargeReference set to 0 and only render full grass up to the uGridsToLoad distance by not utilizing the ExtendGrassDistance NGIO feature.

The grass brightness modifiers are important to be tweaked so that the grass in LOD approximately matches the appearance of the full grass, providing as seamless a transition as possible. These modifiers are in RGB colors, so instead of altering the brightness of the entire grass the same, it allows for more control over the brightness of the individual color variations. It is easiest to lower these in tandem at first to get the overall brightness down to where it needs to be, and then tweaking the individual colors one way or the other to achieve a much closer result. Ideally, grass mod authors would test these settings and provide recommendations. However, ENB can affect the results as well, as it adds additional shadowing to grasses, which typically require a lower grass brightness in LOD to compensate. Most issues with too bright grass LOD can be resolved by lowering these modifiers here rather than attempting to lower the Direct and Ambient light of the textures themselves in Texgen.

No additional GUI settings are required when running DynDOLOD to generate grass LOD at this time.

Grass cache files[edit]

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NOTE

The information presented here is technical information that is not necessary to understand to successfully use the grass cache and grass LODs. It is provided for informative purposes only.

Grass cache files are actually an unused feature of Skyrim, Skyrim Special Edition, and Fallout 4. Bethesda did have it working in original Skyrim using pre-generated grass cache files located in Skyrim - Misc.bsa, but they turned it off by default (INI setting bAllowLoadGrass:Grass) and instead forced the game to create grass every time the user loads the cell (INI setting bAllowCreateGrass:Grass). Grass cache can be generated via the CreateGrassAt console command presumably. Alternately, the grass cache can be generated by setting bGenerateGrassDataFiles:Grass to 1 in Skyrim.ini, which will create the grass cache files within a grass folder within the data directory.

Naming convention[edit]

Grass cache files are named like this: <worldspace>x<x cell coordinates padded to 4 characters with 0>y<y cell coordinates padded to 4 characters with 0>.gid. So if a grass cache file is named tamrielx-047y0038.gid, that means it applies to Tamriel <-47, 38>. No Grass In Objects renames the file extension to .cgid in order to bypass the erroneous grass cache files in Skyrim - Misc.bsa.

Hex file structure[edit]

Below is a hex file example of a grass cache file that has been stripped of the data required to populate the grass throughout the cell (essentially, it is a blank grass cache file in that it will not show any grass, despite specifying a grass.

01 00 00 00
18 00 00 00
6c 61 6e 64 73 63 61 70 65 5c 47 72 61 73 73 5c 49 76 79 2e 6e 69 66
00 00 00 5c 43 d0 bd d1 8b 00 74
01 01 00
00 00 00 00

01 00 00 00
This is the start of the file. The initial byte (01) tells the hexadecimal number of grass textures/meshes within the cell (1 in this case).

18 00 00 00
The byte at position 4 (18) tells the hexadecimal number of characters that make up the string identifying the grass mesh file location. It always includes an extra byte in its calculation. 18 translates to 24 bytes, so the string will be 23 bytes long.

6c 61 6e 64 73 63 61 70 65 5c 47 72 61 73 73 5c 49 76 79 2e 6e 69 66
This is the string identifying the grass mesh file location (landscape\Grass\Ivy.nif). As noted above, the string is 23 bytes long.

00 00 00 5c 43 d0 bd d1 8b 00 74
This seems to be unique information that relates in some way to describing the grass. It is currently unknown what it means specifically, but it seems to be tied somehow to the name and order within the file.

01 01 00
These bytes are iterated near the beginning of each grass texture/mesh identification prior to the data that tells where to place grass. They seem to serve as a kind of padding.

00 00 00 00
The first byte here needs to be 00 if there is no grass for the mesh/texture. Any other value seems to indicate that there is data following these bytes that tells the game where to place the grass. If, for example, you had it set to 01 with no data following, it will crash the game.