Units: add support for light power units in Watt. Use for Eevee lights.

This affects point, spot and area lights. Sun light strength remains without
a unit. This change does not affect .blend file compatibility in any way, as
with the rest of the unit system it's purely a display and editing feature.

Not used for Cycles yet, that will be done after unifying the settings with
Eevee.

4 files changed, 40 insertions, 11 deletions

diff --git a/source/blender/makesrna/RNA_types.h b/source/blender/makesrna/RNA_types.h
index 1742e8b8795..a02bf644620 100644
--- a/source/blender/makesrna/RNA_types.h
+++ b/source/blender/makesrna/RNA_types.h
@@ -90,6 +90,7 @@ typedef enum PropertyUnit {
 	PROP_UNIT_VELOCITY     = (7 << 16),   /* m/s */
 	PROP_UNIT_ACCELERATION = (8 << 16),   /* m/(s^2) */
 	PROP_UNIT_CAMERA       = (9 << 16),   /* mm */
+	PROP_UNIT_POWER        = (10 << 16),  /* W */
 } PropertyUnit;
 
 #define RNA_SUBTYPE_UNIT(subtype)       ((subtype) &  0x00FF0000)
@@ -146,6 +147,9 @@ typedef enum PropertySubType {
 	/* booleans */
 	PROP_LAYER             = 40,
 	PROP_LAYER_MEMBER      = 41,
+
+	/* light */
+	PROP_POWER             = 42 | PROP_UNIT_POWER,
 } PropertySubType;
 
 /* Make sure enums are updated with these */
diff --git a/source/blender/makesrna/intern/makesrna.c b/source/blender/makesrna/intern/makesrna.c
index 7230b65738b..df8911f425c 100644
--- a/source/blender/makesrna/intern/makesrna.c
+++ b/source/blender/makesrna/intern/makesrna.c
@@ -2579,6 +2579,7 @@ static const char *rna_property_subtypename(PropertySubType type)
 		case PROP_LAYER: return "PROP_LAYER";
 		case PROP_LAYER_MEMBER: return "PROP_LAYER_MEMBER";
 		case PROP_PASSWORD: return "PROP_PASSWORD";
+		case PROP_POWER: return "PROP_POWER";
 		default:
 		{
 			/* in case we don't have a type preset that includes the subtype */
@@ -2605,6 +2606,7 @@ static const char *rna_property_subtype_unit(PropertySubType type)
 		case PROP_UNIT_VELOCITY:     return "PROP_UNIT_VELOCITY";
 		case PROP_UNIT_ACCELERATION: return "PROP_UNIT_ACCELERATION";
 		case PROP_UNIT_CAMERA:       return "PROP_UNIT_CAMERA";
+		case PROP_UNIT_POWER:        return "PROP_UNIT_POWER";
 		default:                     return "PROP_UNIT_UNKNOWN";
 	}
 }
diff --git a/source/blender/makesrna/intern/rna_lamp.c b/source/blender/makesrna/intern/rna_lamp.c
index dc82e8b28f8..c15186399e7 100644
--- a/source/blender/makesrna/intern/rna_lamp.c
+++ b/source/blender/makesrna/intern/rna_lamp.c
@@ -137,12 +137,6 @@ static void rna_def_light(BlenderRNA *brna)
 	                         "Falloff distance - the light is at half the original intensity at this point");
 	RNA_def_property_update(prop, 0, "rna_Light_draw_update");
 
-	prop = RNA_def_property(srna, "energy", PROP_FLOAT, PROP_NONE);
-	RNA_def_property_float_default(prop, 10.0f);
-	RNA_def_property_ui_range(prop, 0, 1000000.0f, 1, 3);
-	RNA_def_property_ui_text(prop, "Energy", "Amount of light emitted");
-	RNA_def_property_update(prop, 0, "rna_Light_draw_update");
-
 	prop = RNA_def_property(srna, "color", PROP_FLOAT, PROP_COLOR);
 	RNA_def_property_float_sdna(prop, NULL, "r");
 	RNA_def_property_array(prop, 3);
@@ -187,6 +181,30 @@ static void rna_def_light(BlenderRNA *brna)
 	rna_def_animdata_common(srna);
 }
 
+static void rna_def_light_energy(StructRNA *srna, bool distant)
+{
+	PropertyRNA *prop;
+
+	if(distant) {
+		/* Distant light strength has no unit defined, it's proportional to
+		 * Watt/m^2 and is not sensitive to scene unit scale. */
+		prop = RNA_def_property(srna, "energy", PROP_FLOAT, PROP_NONE);
+		RNA_def_property_float_default(prop, 10.0f);
+		RNA_def_property_ui_range(prop, 0.0f, 10.0f, 1, 3);
+		RNA_def_property_ui_text(prop, "Strength", "Amount of light emitted");
+		RNA_def_property_update(prop, 0, "rna_Light_draw_update");
+	}
+	else {
+		/* Lights with a location have power in Watt, which is sensitive to
+		 * scene unit scale. */
+		prop = RNA_def_property(srna, "energy", PROP_FLOAT, PROP_POWER);
+		RNA_def_property_float_default(prop, 10.0f);
+		RNA_def_property_ui_range(prop, 0.0f, 1000000.0f, 1, 5);
+		RNA_def_property_ui_text(prop, "Power", "Amount of light emitted");
+		RNA_def_property_update(prop, 0, "rna_Light_draw_update");
+	}
+}
+
 static void rna_def_light_falloff(StructRNA *srna)
 {
 	PropertyRNA *prop;
@@ -245,7 +263,7 @@ static void rna_def_light_falloff(StructRNA *srna)
 	RNA_def_property_update(prop, 0, "rna_Light_draw_update");
 }
 
-static void rna_def_light_shadow(StructRNA *srna, int sun)
+static void rna_def_light_shadow(StructRNA *srna, bool sun)
 {
 	PropertyRNA *prop;
 
@@ -405,8 +423,9 @@ static void rna_def_point_light(BlenderRNA *brna)
 	RNA_def_struct_ui_text(srna, "Point Light", "Omnidirectional point Light");
 	RNA_def_struct_ui_icon(srna, ICON_LIGHT_POINT);
 
+	rna_def_light_energy(srna, false);
 	rna_def_light_falloff(srna);
-	rna_def_light_shadow(srna, 0);
+	rna_def_light_shadow(srna, false);
 }
 
 static void rna_def_area_light(BlenderRNA *brna)
@@ -427,7 +446,8 @@ static void rna_def_area_light(BlenderRNA *brna)
 	RNA_def_struct_ui_text(srna, "Area Light", "Directional area Light");
 	RNA_def_struct_ui_icon(srna, ICON_LIGHT_AREA);
 
-	rna_def_light_shadow(srna, 0);
+	rna_def_light_energy(srna, false);
+	rna_def_light_shadow(srna, false);
 	rna_def_light_falloff(srna);
 
 	prop = RNA_def_property(srna, "shape", PROP_ENUM, PROP_NONE);
@@ -464,8 +484,9 @@ static void rna_def_spot_light(BlenderRNA *brna)
 	RNA_def_struct_ui_text(srna, "Spot Light", "Directional cone Light");
 	RNA_def_struct_ui_icon(srna, ICON_LIGHT_SPOT);
 
+	rna_def_light_energy(srna, false);
 	rna_def_light_falloff(srna);
-	rna_def_light_shadow(srna, 0);
+	rna_def_light_shadow(srna, false);
 
 	prop = RNA_def_property(srna, "use_square", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_sdna(prop, NULL, "mode", LA_SQUARE);
@@ -502,7 +523,8 @@ static void rna_def_sun_light(BlenderRNA *brna)
 	RNA_def_struct_ui_text(srna, "Sun Light", "Constant direction parallel ray Light");
 	RNA_def_struct_ui_icon(srna, ICON_LIGHT_SUN);
 
-	rna_def_light_shadow(srna, 1);
+	rna_def_light_energy(srna, true);
+	rna_def_light_shadow(srna, true);
 }
 
 void RNA_def_light(BlenderRNA *brna)
diff --git a/source/blender/makesrna/intern/rna_rna.c b/source/blender/makesrna/intern/rna_rna.c
index 594d947b996..6af3e30f1ab 100644
--- a/source/blender/makesrna/intern/rna_rna.c
+++ b/source/blender/makesrna/intern/rna_rna.c
@@ -116,6 +116,7 @@ const EnumPropertyItem rna_enum_property_unit_items[] = {
 	{PROP_UNIT_ACCELERATION, "ACCELERATION", 0, "Acceleration", ""},
 	{PROP_UNIT_MASS, "MASS", 0, "Mass", ""},
 	{PROP_UNIT_CAMERA, "CAMERA", 0, "Camera", ""},
+	{PROP_UNIT_POWER, "POWER", 0, "Power", ""},
 	{0, NULL, 0, NULL, NULL},
 };