Fix GLTF light import

3 files changed, 19 insertions, 11 deletions

diff --git a/modules/gltf/doc_classes/GLTFLight.xml b/modules/gltf/doc_classes/GLTFLight.xml
index 91df7d8014..b4f03cd1ed 100644
--- a/modules/gltf/doc_classes/GLTFLight.xml
+++ b/modules/gltf/doc_classes/GLTFLight.xml
@@ -7,17 +7,25 @@
 	<tutorials>
 	</tutorials>
 	<members>
-		<member name="color" type="Color" setter="set_color" getter="get_color" default="Color(0, 0, 0, 1)">
+		<member name="color" type="Color" setter="set_color" getter="get_color" default="Color(1, 1, 1, 1)">
+			The [Color] of the light. Defaults to white. A black color causes the light to have no effect.
 		</member>
 		<member name="inner_cone_angle" type="float" setter="set_inner_cone_angle" getter="get_inner_cone_angle" default="0.0">
+			The inner angle of the cone in a spotlight. Must be less than or equal to the outer cone angle.
+			Within this angle, the light is at full brightness. Between the inner and outer cone angles, there is a transition from full brightness to zero brightness. When creating a Godot [SpotLight3D], the ratio between the inner and outer cone angles is used to calculate the attenuation of the light.
 		</member>
-		<member name="intensity" type="float" setter="set_intensity" getter="get_intensity" default="0.0">
+		<member name="intensity" type="float" setter="set_intensity" getter="get_intensity" default="1.0">
+			The intensity of the light. This is expressed in candelas (lumens per steradian) for point and spot lights, and lux (lumens per m²) for directional lights. When creating a Godot light, this value is converted to a unitless multiplier.
 		</member>
 		<member name="light_type" type="String" setter="set_light_type" getter="get_light_type" default="&quot;&quot;">
+			The type of the light. The values accepted by Godot are "point", "spot", and "directional", which correspond to Godot's [OmniLight3D], [SpotLight3D], and [DirectionalLight3D] respectively.
 		</member>
-		<member name="outer_cone_angle" type="float" setter="set_outer_cone_angle" getter="get_outer_cone_angle" default="0.0">
+		<member name="outer_cone_angle" type="float" setter="set_outer_cone_angle" getter="get_outer_cone_angle" default="0.785398">
+			The outer angle of the cone in a spotlight. Must be greater than or equal to the inner angle.
+			At this angle, the light drops off to zero brightness. Between the inner and outer cone angles, there is a transition from full brightness to zero brightness. If this angle is a half turn, then the spotlight emits in all directions. When creating a Godot [SpotLight3D], the outer cone angle is used as the angle of the spotlight.
 		</member>
-		<member name="range" type="float" setter="set_range" getter="get_range" default="0.0">
+		<member name="range" type="float" setter="set_range" getter="get_range" default="inf">
+			The range of the light, beyond which the light has no effect. GLTF lights with no range defined behave like physical lights (which have infinite range). When creating a Godot light, the range is clamped to 4096.
 		</member>
 	</members>
 </class>
diff --git a/modules/gltf/gltf_document.cpp b/modules/gltf/gltf_document.cpp
index df2856ec7c..97367b15df 100644
--- a/modules/gltf/gltf_document.cpp
+++ b/modules/gltf/gltf_document.cpp
@@ -5074,7 +5074,7 @@ Node3D *GLTFDocument::_generate_light(Ref<GLTFState> state, Node *scene_parent,
 	const float range = CLAMP(l->range, 0, 4096);
 	// Doubling the range will double the effective brightness, so we need double attenuation (half brightness).
 	// We want to have double intensity give double brightness, so we need half the attenuation.
-	const float attenuation = range / intensity;
+	const float attenuation = range / (intensity * 2048);
 	if (l->light_type == "point") {
 		OmniLight3D *light = memnew(OmniLight3D);
 		light->set_param(OmniLight3D::PARAM_ATTENUATION, attenuation);
@@ -5150,13 +5150,13 @@ GLTFLightIndex GLTFDocument::_convert_light(Ref<GLTFState> state, Light3D *p_lig
 		OmniLight3D *light = cast_to<OmniLight3D>(p_light);
 		l->range = light->get_param(OmniLight3D::PARAM_RANGE);
 		float attenuation = p_light->get_param(OmniLight3D::PARAM_ATTENUATION);
-		l->intensity = l->range / attenuation;
+		l->intensity = l->range / (attenuation * 2048);
 	} else if (cast_to<SpotLight3D>(p_light)) {
 		l->light_type = "spot";
 		SpotLight3D *light = cast_to<SpotLight3D>(p_light);
 		l->range = light->get_param(SpotLight3D::PARAM_RANGE);
 		float attenuation = light->get_param(SpotLight3D::PARAM_ATTENUATION);
-		l->intensity = l->range / attenuation;
+		l->intensity = l->range / (attenuation * 2048);
 		l->outer_cone_angle = Math::deg2rad(light->get_param(SpotLight3D::PARAM_SPOT_ANGLE));
 
 		// This equation is the inverse of the import equation (which has a desmos link).
diff --git a/modules/gltf/gltf_light.h b/modules/gltf/gltf_light.h
index 079fb18151..62a20d2f16 100644
--- a/modules/gltf/gltf_light.h
+++ b/modules/gltf/gltf_light.h
@@ -42,12 +42,12 @@ protected:
 	static void _bind_methods();
 
 private:
-	Color color;
-	float intensity = 0.0f;
+	Color color = Color(1.0f, 1.0f, 1.0f);
+	float intensity = 1.0f;
 	String light_type;
-	float range = 0.0f;
+	float range = INFINITY;
 	float inner_cone_angle = 0.0f;
-	float outer_cone_angle = 0.0f;
+	float outer_cone_angle = Math_TAU / 8.0f;
 
 public:
 	Color get_color();