Lights: change sun light size to be specified as angle

This is the angular diameter as seen from earth, which is between 0.526° and
0.545° in reality. Sharing the size with other light types did not make much
sense and meant the unit was unclear.

Differential Revision: https://developer.blender.org/D4819

5 files changed, 19 insertions, 9 deletions

diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index 6da88a769f5..f376eb8ec67 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -1490,7 +1490,7 @@ class CyclesPreferences(bpy.types.AddonPreferences):
                 break
 
         if not found_device:
-            col = box.column(align=True);
+            col = box.column(align=True)
             col.label(text="No compatible GPUs found for path tracing", icon='INFO')
             col.label(text="Cycles will render on the CPU", icon='BLANK1')
             return
diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 9714067b08e..5ff88367f22 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -1345,8 +1345,10 @@ class CYCLES_LIGHT_PT_light(CyclesButtonsPanel, Panel):
         col.prop(light, "energy")
         col.separator()
 
-        if light.type in {'POINT', 'SUN', 'SPOT'}:
+        if light.type in {'POINT', 'SPOT'}:
             col.prop(light, "shadow_soft_size", text="Size")
+        elif light.type == 'SUN':
+            col.prop(light, "angle")
         elif light.type == 'AREA':
             col.prop(light, "shape", text="Shape")
             sub = col.column(align=True)
diff --git a/intern/cycles/blender/blender_object.cpp b/intern/cycles/blender/blender_object.cpp
index 1094ff37afb..c07e896ab33 100644
--- a/intern/cycles/blender/blender_object.cpp
+++ b/intern/cycles/blender/blender_object.cpp
@@ -149,7 +149,7 @@ void BlenderSync::sync_light(BL::Object &b_parent,
     // }
     case BL::Light::type_SUN: {
       BL::SunLight b_sun_light(b_light);
-      light->size = b_sun_light.shadow_soft_size();
+      light->angle = b_sun_light.angle();
       light->type = LIGHT_DISTANT;
       break;
     }
diff --git a/intern/cycles/render/light.cpp b/intern/cycles/render/light.cpp
index ef4bd4260c9..5c3f1c35bdc 100644
--- a/intern/cycles/render/light.cpp
+++ b/intern/cycles/render/light.cpp
@@ -398,11 +398,18 @@ void LightManager::device_update_distribution(Device *,
     distribution[offset].lamp.size = light->size;
     totarea += lightarea;
 
-    if (light->size > 0.0f && light->use_mis)
-      use_lamp_mis = true;
-    if (light->type == LIGHT_BACKGROUND) {
+    if (light->type == LIGHT_DISTANT) {
+      use_lamp_mis |= (light->angle > 0.0f && light->use_mis);
+    }
+    else if (light->type == LIGHT_POINT || light->type == LIGHT_SPOT) {
+      use_lamp_mis |= (light->size > 0.0f && light->use_mis);
+    }
+    else if (light->type == LIGHT_AREA) {
+      use_lamp_mis |= light->use_mis;
+    }
+    else if (light->type == LIGHT_BACKGROUND) {
       num_background_lights++;
-      background_mis = light->use_mis;
+      background_mis |= light->use_mis;
     }
 
     light_index++;
@@ -725,8 +732,8 @@ void LightManager::device_update_points(Device *, DeviceScene *dscene, Scene *sc
     else if (light->type == LIGHT_DISTANT) {
       shader_id &= ~SHADER_AREA_LIGHT;
 
-      float radius = light->size;
-      float angle = atanf(radius);
+      float angle = light->angle / 2.0f;
+      float radius = tanf(angle);
       float cosangle = cosf(angle);
       float area = M_PI_F * radius * radius;
       float invarea = (area > 0.0f) ? 1.0f / area : 1.0f;
diff --git a/intern/cycles/render/light.h b/intern/cycles/render/light.h
index a7bffde7a8d..79450ea5f8d 100644
--- a/intern/cycles/render/light.h
+++ b/intern/cycles/render/light.h
@@ -47,6 +47,7 @@ class Light : public Node {
 
   float3 dir;
   float size;
+  float angle;
 
   float3 axisu;
   float sizeu;