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, 1 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl b/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
index eb03df67f6b..a54cefc5b85 100644
--- a/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
@@ -24,7 +24,7 @@ uniform sampler2DArray planarDepth;
 
 /* ------ Lights ----- */
 struct LightData {
-	vec4 position_influence;      /* w : InfluenceRadius */
+	vec4 position_influence;      /* w : InfluenceRadius (inversed and squared) */
 	vec4 color_spec;              /* w : Spec Intensity */
 	vec4 spotdata_radius_shadow;  /* x : spot size, y : spot blend, z : radius, w: shadow id */
 	vec4 rightvec_sizex;          /* xyz: Normalized up vector, w: area size X or spot scale X */