|The *.cax file is to GeomCaches, what a *.dds file is to Textures. It gets generated based on your engine version from your *.abc and *.cbc.|
The format is subject to change with future engine updates and is not backwards-compatible!
Keep your *.abc and *.cbc, just like you keep your *.tif files.
See the Batch Conversion section for information on how to update all *.cax files at once.
Creating GeomCache Assets
Make sure you loaded the Maya Alembic export plugin: from Maya's Main Menu bar -> Windows -> Settings/Preferences -> Plug-In Manager, tick the "Loaded" and "Auto-load" checkbox for the "AbcExport.mll".
1. Run the AbcMat script (inside the Crytek Shelf), to prepare your scene for export. This script slightly modifies your scene to work around some limitations in Maya's Alembic exporter.
2. Bring up the Maya Alembic exporter GUI first.
3. Under the advanced Options, (scroll to the bottom) & make sure to have the essential flags enabled, as in the picture below.
After you set the options on step 3. do not use Maya's "Alembic Export" Options window -> "Export Selection" ( or "Export All" ) button on the bottom! Otherwise, you will loose the material IDs you set and end with just ONE material ID for your Alembic asset.
Once you have set these flags, click the close button & go to the Crytek Exporter!
4. Just select the mesh nodes you wish to export and click the "CryAbc" shelf button. A file dialog will pop up and ask you to set the file location and file name for the Alembic file.
Alembic Export from 3ds Max
These are the essential exporter settings:
rc.exe /refresh /threads *.abc
Using GeomCaches in Sandbox
Set up your import properties. There are presets for most use-cases that you'll encounter in production:
The settings in detail:
Here's an example of an independent GeomCache prop from Ryse that loads and unloads as the player moves closer or further:
This sequence illustrates how different techniques affect draw-calls and data-rate, using "e_GeomCacheDebugDrawMode 3" to color instances:
The overall memory consumption and streaming performance of all active GeomCaches can be profiled, using "e_GeomCacheDebug 1".
- Playback from Disk/Memory - whether this GeomCache is streamed or completely loaded into memory.
- Average Animation Data Rate - high values can lead to animation stuttering.
- Animated/Static Tris/Verts - like with regular geometry, more triangles/vertices = slower rendering.
- Animated/Static Meshes - the number of individual meshes (unless instanced) directly translates into draw-calls. Meshes with multiple sub-materials cost multiple draw-calls.
The Statistics Overlay can be enabled in the preferences:
Debugging & Troubleshooting
e_GeomCacheDebug - displays GeomCache streaming debug information. Avoid having a full streaming buffer since it will lead to animation stalls:
e_GeomCacheDebugFilter - show debug info only caches with this string in its name.