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, 22 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/light.c b/source/blender/blenkernel/intern/light.c
index 05b2eb82daf..1c3acb6a73a 100644
--- a/source/blender/blenkernel/intern/light.c
+++ b/source/blender/blenkernel/intern/light.c
@@ -80,6 +80,7 @@ void BKE_light_init(Light *la)
   la->contact_thickness = 0.2f;
   la->spec_fac = 1.0f;
   la->att_dist = 40.0f;
+  la->sun_angle = DEG2RADF(0.526f);
 
   curvemapping_initialize(la->curfalloff);
 }
diff --git a/source/blender/blenloader/intern/versioning_280.c b/source/blender/blenloader/intern/versioning_280.c
index 9d8fa2d06d0..526931d1a45 100644
--- a/source/blender/blenloader/intern/versioning_280.c
+++ b/source/blender/blenloader/intern/versioning_280.c
@@ -3418,5 +3418,12 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
     LISTBASE_FOREACH (bArmature *, arm, &bmain->armatures) {
       arm->flag &= ~(ARM_FLAG_UNUSED_7 | ARM_FLAG_UNUSED_9);
     }
+
+    /* Initializes sun lights with the new angular diameter property */
+    if (!DNA_struct_elem_find(fd->filesdna, "Light", "float", "sun_angle")) {
+      LISTBASE_FOREACH (Light *, light, &bmain->lights) {
+        light->sun_angle = 2.0f * atanf(light->area_size);
+      }
+    }
   }
 }
diff --git a/source/blender/draw/engines/eevee/eevee_lights.c b/source/blender/draw/engines/eevee/eevee_lights.c
index 730372bce9c..f64cd340ab2 100644
--- a/source/blender/draw/engines/eevee/eevee_lights.c
+++ b/source/blender/draw/engines/eevee/eevee_lights.c
@@ -672,6 +672,9 @@ static void light_shape_parameters_set(EEVEE_Light *evli, const Light *la, float
       evli->sizey = max_ff(0.003f, la->area_size * scale[1] * 0.5f);
     }
   }
+  else if (la->type == LA_SUN) {
+    evli->radius = max_ff(0.001f, tanf(la->sun_angle / 2.0f));
+  }
   else {
     evli->radius = max_ff(0.001f, la->area_size);
   }
diff --git a/source/blender/makesdna/DNA_light_types.h b/source/blender/makesdna/DNA_light_types.h
index 6bd118b7be9..5e881053910 100644
--- a/source/blender/makesdna/DNA_light_types.h
+++ b/source/blender/makesdna/DNA_light_types.h
@@ -66,6 +66,9 @@ typedef struct Light {
   short area_shape;
   float area_size, area_sizey, area_sizez;
 
+  float sun_angle;
+  char _pad3[4];
+
   /* texact is for buttons */
   short texact, shadhalostep;
 
diff --git a/source/blender/makesrna/intern/rna_light.c b/source/blender/makesrna/intern/rna_light.c
index da2b5752a0f..54c8049d4d2 100644
--- a/source/blender/makesrna/intern/rna_light.c
+++ b/source/blender/makesrna/intern/rna_light.c
@@ -545,12 +545,20 @@ static void rna_def_spot_light(BlenderRNA *brna)
 static void rna_def_sun_light(BlenderRNA *brna)
 {
   StructRNA *srna;
+  PropertyRNA *prop;
 
   srna = RNA_def_struct(brna, "SunLight", "Light");
   RNA_def_struct_sdna(srna, "Light");
   RNA_def_struct_ui_text(srna, "Sun Light", "Constant direction parallel ray Light");
   RNA_def_struct_ui_icon(srna, ICON_LIGHT_SUN);
 
+  prop = RNA_def_property(srna, "angle", PROP_FLOAT, PROP_ANGLE);
+  RNA_def_property_float_sdna(prop, NULL, "sun_angle");
+  RNA_def_property_float_default(prop, DEG2RADF(0.526f));
+  RNA_def_property_range(prop, DEG2RADF(0.0f), DEG2RADF(180.0f));
+  RNA_def_property_ui_text(prop, "Angle", "Angular diameter of the Sun as seen from the Earth");
+  RNA_def_property_update(prop, 0, "rna_Light_update");
+
   rna_def_light_energy(srna, true);
   rna_def_light_shadow(srna, true);
 }