Eevee: Add Light Threshold value

This is an important change. Starting from now, all lights have a finite
influence radius (similar to the old sphere option for BI).

In order to avoid costly setup time, this distance is first computed
automatically based on a light threshold. The distance is computed
at the light origin and using the inverse square falloff. The setting
can be found inside the render settings panel > shadow tab.

This light threshold does not take the light shape into account an may not
suit every case. That's why we provide a per lamp override where you can
just set the cutt off distance (Light Properties Panel > Light >
Custom Distance).

The influence distance is also used as shadow far clip distance.

This influence distance does not concerns sun lights that still have a
far clip distance.

---

This change is important because it makes it possible to cull lights
an improve performance drastically in the future.

1 files changed, 12 insertions, 0 deletions

diff --git a/source/blender/blenloader/intern/versioning_280.c b/source/blender/blenloader/intern/versioning_280.c
index 9521c05f7f0..1871aea86a4 100644
--- a/source/blender/blenloader/intern/versioning_280.c
+++ b/source/blender/blenloader/intern/versioning_280.c
@@ -2265,6 +2265,18 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 			}
 		}
 
+		if (!DNA_struct_elem_find(fd->filesdna, "SceneEEVEE", "float", "light_threshold")) {
+			for (Scene *scene = bmain->scene.first; scene; scene = scene->id.next) {
+				scene->eevee.light_threshold = 0.01f;
+			}
+		}
+
+		if (!DNA_struct_elem_find(fd->filesdna, "Lamp", "float", "att_dist")) {
+			for (Lamp *la = bmain->lamp.first; la; la = la->id.next) {
+				la->att_dist = la->clipend;
+			}
+		}
+
 		if (!DNA_struct_elem_find(fd->filesdna, "Brush", "char", "weightpaint_tool")) {
 			/* Magic defines from old files (2.7x) */