How to prevent spot lights from ignoring objects behind it

Graphics
1

I have a full-screen quad that I place in front of the camera and use to apply an effect to the scene. In other words, I’m using a screen-space effect to draw some objects in the scene.

The shader attached to the quad requires the forward base pass and an additive pass for each light as usual. The idea to emulate scene lighting on the object I’m drawing into the scene in screen space. The problem is, most of my lights are spot lights, which skip their additive pass if the object “can’t be reached” by the light. Since the quad may be behind the light at given angles, it may skip the pass completely from certain camera transforms.

This is a problem, I don’t want unity to automatically skip the additive pass because it thinks what it’s trying to light can’t be touched by it. is there a way to disable this behaviour?

2

Thinking a possible workaround could be to add some vertices or tiny triangles way behind the full-screen quad mesh to “trick” the bounds/culling logic into thinking the camera-quad is huge, but that feels really hacky.

Edit: actually, found a somewhat less hacky way of doing it. Take the mesh that the full-screen quad is using and set the bounds to a large value:

Mesh quadCopy = Instantiate(fullScreenQuad.GetComponent<MeshFilter>().mesh) as Mesh;
quadCopy.bounds = new Bounds(Vector3.zero, new Vector3(100000, 100000, 100000));
quadCopy.name = "Quad Copy (Huge Bounds)";
fullScreenQuad.GetComponent<MeshFilter>().mesh = quadCopy;