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, 1 insertions, 0 deletions

diff --git a/release/scripts/startup/bl_ui/properties_render.py b/release/scripts/startup/bl_ui/properties_render.py
index bbb1a067dd7..61804bae9d8 100644
--- a/release/scripts/startup/bl_ui/properties_render.py
+++ b/release/scripts/startup/bl_ui/properties_render.py
@@ -390,6 +390,7 @@ class RENDER_PT_eevee_shadows(RenderButtonsPanel, Panel):
         col.prop(props, "shadow_cascade_size", text="Cascade Size")
         col.prop(props, "use_shadow_high_bitdepth")
         col.prop(props, "use_soft_shadows")
+        col.prop(props, "light_threshold")
 
 
 class RENDER_PT_eevee_sampling(RenderButtonsPanel, Panel):