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, 9 insertions, 2 deletions

diff --git a/intern/cycles/render/light.cpp b/intern/cycles/render/light.cpp
index d4c233e3bb3..ef4bd4260c9 100644
--- a/intern/cycles/render/light.cpp
+++ b/intern/cycles/render/light.cpp
@@ -114,6 +114,8 @@ NODE_DEFINE(Light)
   type_enum.insert("spot", LIGHT_SPOT);
   SOCKET_ENUM(type, "Type", type_enum, LIGHT_POINT);
 
+  SOCKET_COLOR(strength, "Strength", make_float3(1.0f, 1.0f, 1.0f));
+
   SOCKET_POINT(co, "Co", make_float3(0.0f, 0.0f, 0.0f));
 
   SOCKET_VECTOR(dir, "Dir", make_float3(0.0f, 0.0f, 0.0f));
@@ -162,6 +164,9 @@ void Light::tag_update(Scene *scene)
 
 bool Light::has_contribution(Scene *scene)
 {
+  if (strength == make_float3(0.0f, 0.0f, 0.0f)) {
+    return false;
+  }
   if (is_portal) {
     return false;
   }
@@ -672,7 +677,6 @@ void LightManager::device_update_points(Device *, DeviceScene *dscene, Scene *sc
     float3 co = light->co;
     Shader *shader = (light->shader) ? light->shader : scene->default_light;
     int shader_id = scene->shader_manager->get_shader_id(shader);
-    int samples = light->samples;
     int max_bounces = light->max_bounces;
     float random = (float)light->random_id * (1.0f / (float)0xFFFFFFFF);
 
@@ -697,7 +701,10 @@ void LightManager::device_update_points(Device *, DeviceScene *dscene, Scene *sc
     }
 
     klights[light_index].type = light->type;
-    klights[light_index].samples = samples;
+    klights[light_index].samples = light->samples;
+    klights[light_index].strength[0] = light->strength.x;
+    klights[light_index].strength[1] = light->strength.y;
+    klights[light_index].strength[2] = light->strength.z;
 
     if (light->type == LIGHT_POINT) {
       shader_id &= ~SHADER_AREA_LIGHT;