Hey! I’m trying to drive my Unreal Engine environment via C++ at runtime using the Celestial Vault plugin. So far I’ve managed to integrate all controls, except for Star Field Intensity. The end result I’m looking for is to have the ability to either dim the stars, or reduce the number of them, driven by a percentage parameter.
So far, I’ve tried:
Dynamically converting the MI_Stars material to a dynamic material instance, and setting the GlobalSizeFactor parameter.
Overriding the Exposure Bias on the Post Process Volume attached to the DaySequenceActor.
Changing the MaxVisibleMagnitude value on the DaySequenceActor.
However, none of these have yielded any results so far. Has anyone got any insights into why this might be, or if it is at all possible. I understand the stars are driven by a pre-configured csv, so not sure if they can be changed at runtime?
Hi,
Sorry for the late answer, I just came across your post.
Are you using the 5.8 version? The Star Material changed a bit in this one, using a conservative energy system that ensures the right brightness level based on Magnitude and Screen size.
MaxVisibleMagnitude clamp the number of generated stars in the ISM component. It help reduce the number and increase performance. 6 is typical for eye vision. You can try lower values to have fewer stars, but it doesn’t help with their brightness on screen.
Stars are generated from their exact magnitude, so there is no need to change the CSV.
But the setting to dim the visual is the Magnitude Offset, which artificially shifts the star’s input magnitude in the shader, while keeping the relative brightness consistent.
You might encounter some pixel saturation, which you can probably mitigate by increasing the size using Base Angular Size. Note that this final size is clamped by the Maximum Pixel Size value, which you’ll probably have to increase.
Make sure you also set the right Mask Average Falloff value corresponding to the mask, the brightness computations are off.
The exposure Bias on the PPV will apply globally to the scene, so it won’t help much here.