Wondering if there is a way to edit the frustum of a spotlight.
What I am trying to achieve is a spotlight that will only start to contribute and cast shadows a certain distance away from its location. For example, the first couple of feet from the spotlight it does not contribute any light or cast any shadows, but everything after that will be lit and cast shadows.
[July 31 2025 Update]
For added clarification, this is what I am after, the issue with this current setup is that the frustum only controlled by a light function so its only affecting the intensity of the light. If an object goes between the start of the light and the start of the beam it will shadow
You’d have to change the clipping plane of the shadow depth capture in the engine code which I’m not sure is possible, definitely isn’t something for a novice. You’d also have a hard edge where the shadow starts and all sorts of unintended light leaking, which would require more effort to fix.
Basically unless you are comfortable with graphics programming, it’s basically impossible. Whatever it is you think you need this for, there is probably a better solution.
The way you describe it, a rect light might be able to do what you want. However, the light shape is not round but maybe you could superimpose several if you need a round shape.
Also, you might need to enable raytraced shadows on the rect lights for accurate shadows casting.
This is the start of the rabbit hole I’ve been going down, assuming that at some point I will be able to edit the “Near Clipping Plane” (Using the same terminology as the CineCamera) of the shadow depth capture.
There is really no other way that would suit the needs that I am looking for, it will have to be this spotlight frustum.
Actually another option would be to modify the hardware raytraced shadows, this would be a lot easier since it would just return a miss a fixed distance from the light if the ray didn’t hit a mesh, shouldn’t have the same negative side effects as shadowmaps. Could likely also be done for distance field shadows if you don’t care about the resolution loss.
Both still require editing the engine code but it’s a lot easier than trying to fix all the unintended side effects of modifying the shadow depth clip plane.
