Creating LOD Levels in a Particle System
The following section will go over the intended design flow for creating particle systems will full LOD support. The process can be broken down like so:
Create your overall desired effect. This will be the highest LOD level.
Next, create the lowest LOD level.
Add any other LOD levels between the two in order to create a smooth transition from highest quality to lowest.
Modules can only be added/deleted when editing at the highest LOD level.
In this example, we have a single SubUV emitter. It is set up in such a way that SubUV coordinate 0 shows a number 1, coordinate 1 shows a number 2, and so on. The texture applied looks like this:
We set up the highest LOD level
Highest LOD Level
Once the designer feels the particle system is ready for LOD development, he should select Regenerate Lowest LOD from the toolbar. This will cause the system to regenerate the lowest LOD level. (It will also delete any static LOD levels that were created in the interim.) At the current time, this will simply duplicate the highest LOD level with a lower spawn rate.
After selecting the lowest LOD level, tweaking of values can commence on it to get the appropriate look. One thing to note is that by default, all modules in the static LOD level are marked un-editable. This is represented by the module showing a marbled background.
Modules viewed at highest LOD
Modules viewed at lowest LOD
To edit a module in a static LOD level, it must be enabled. This is done by right-clicking the module and selecting Duplicate from Higher from the context menu.
The available options work as follows:
Duplicate from Higher
Enables the module for editing by duplicating the settings of the next higher LOD.
Share from Higher
Enables the module for editing by sharing the settings of the next higher LOD. This means that editing one will automatically edit the other in the same way.
Duplicate from Highest
Enables the module for editing by duplicating the settings of the highest LOD.
In our example, we have enabled the SubImage Index module for editing and set the index to 3. This results in an emitter showing a yellow 4, and is shown below:
Lowest LOD Level
Note that the spawn rate was automatically set to 10% of the highest LOD level.
The next step would involve adding a static LOD in-between the highest and lowest by pressing the Add LOD before current button (assuming you are still viewing the lowest LOD). The SubImage Index module is enabled and has the index set to 1. This results in the emitter showing a blue 2, as shown below:
LOD Level 1
The same was done for another static LOD between the first static LOD and the lowest LOD by pressing the Add LOD after current button and enabling the SubImage index module. The SubImage Index was set to 2 resulting in an emitter displaying a green 3, as shown below:
LOD Level 2