Cycles/Eevee: unify light strength and color

Cycles lights now use strength and color properties of the light outside
of the shading nodes, just like Eevee. The shading nodes then act as a
multiplier on this, and become optional unless textures, fallof or other
effects are desired.

Backwards compatibility is not exact, as we can't be sure which renderer
the .blend was designed for or even if it was designed for a single one.

If the render engine in the active scene is set to Cycles, lights are
converted to ensure overall light strength remains the same, and removing
unnecessary shader node setups that only included a single emission node.

If the engine is set to Eevee, we increase strength to remove the automatic
100x multiplier that was there to match Cycles.

Differential Revision: https://developer.blender.org/D4588

1 files changed, 3 insertions, 4 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_lights.c b/source/blender/draw/engines/eevee/eevee_lights.c
index 6e6c23205fe..0e24115f849 100644
--- a/source/blender/draw/engines/eevee/eevee_lights.c
+++ b/source/blender/draw/engines/eevee/eevee_lights.c
@@ -645,7 +645,7 @@ float light_attenuation_radius_get(Light *la, float light_threshold)
 
   /* Compute max light power. */
   float power = max_fff(la->r, la->g, la->b);
-  power *= fabsf(la->energy);
+  power *= fabsf(la->energy / 100.0f);
   power *= max_ff(1.0f, la->spec_fac);
   /* Compute the distance (using the inverse square law)
    * at which the light power reaches the light_threshold. */
@@ -683,7 +683,7 @@ static float light_shape_power_get(const Light *la, const EEVEE_Light *evli)
   /* Make illumination power constant */
   if (la->type == LA_AREA) {
     power = 1.0f / (evli->sizex * evli->sizey * 4.0f * M_PI) * /* 1/(w*h*Pi) */
-            80.0f; /* XXX : Empirical, Fit cycles power */
+            0.8f; /* XXX : Empirical, Fit cycles power */
     if (ELEM(la->area_shape, LA_AREA_DISK, LA_AREA_ELLIPSE)) {
       /* Scale power to account for the lower area of the ellipse compared to the surrounding
        * rectangle. */
@@ -691,8 +691,7 @@ static float light_shape_power_get(const Light *la, const EEVEE_Light *evli)
     }
   }
   else if (la->type == LA_SPOT || la->type == LA_LOCAL) {
-    power = 1.0f / (4.0f * evli->radius * evli->radius * M_PI * M_PI) * /* 1/(4*r²*Pi²) */
-            M_PI * M_PI * 10.0; /* XXX : Empirical, Fit cycles power */
+    power = 1.0f / (4.0f * evli->radius * evli->radius * M_PI * M_PI); /* 1/(4*r²*Pi²) */
 
     /* for point lights (a.k.a radius == 0.0) */
     // power = M_PI * M_PI * 0.78; /* XXX : Empirical, Fit cycles power */