Implement per-light Specular property in DirectionalLight3D

doc/classes/Light3D.xml

@@ -98,7 +98,7 @@
 			[b]Note:[/b] [member light_size] is not affected by [member Node3D.scale] (the light's scale or its parent's scale).
 			[b]Note:[/b] PCSS for positional lights is only supported in the Forward+ and Mobile rendering methods, not Compatibility.
 		</member>
-		<member name="light_specular" type="float" setter="set_param" getter="get_param" default="0.5">
+		<member name="light_specular" type="float" setter="set_param" getter="get_param" default="1.0">
 			The intensity of the specular blob in objects affected by the light. At [code]0[/code], the light becomes a pure diffuse light. When not baking emission, this can be used to avoid unrealistic reflections when placing lights above an emissive surface.
 		</member>
 		<member name="light_temperature" type="float" setter="set_temperature" getter="get_temperature">

doc/classes/OmniLight3D.xml

@@ -13,6 +13,7 @@
 		<link title="Faking global illumination">$DOCS_URL/tutorials/3d/global_illumination/faking_global_illumination.html</link>
 	</tutorials>
 	<members>
+		<member name="light_specular" type="float" setter="set_param" getter="get_param" overrides="Light3D" default="0.5" />
 		<member name="omni_attenuation" type="float" setter="set_param" getter="get_param" default="1.0">
 			Controls the distance attenuation function for omnilights.
 			A value of [code]0.0[/code] will maintain a constant brightness through most of the range, but smoothly attenuate the light at the edge of the range. Use a value of [code]2.0[/code] for physically accurate lights as it results in the proper inverse square attenutation.

doc/classes/SpotLight3D.xml

@@ -14,6 +14,7 @@
 		<link title="Third Person Shooter (TPS) Demo">https://godotengine.org/asset-library/asset/2710</link>
 	</tutorials>
 	<members>
+		<member name="light_specular" type="float" setter="set_param" getter="get_param" overrides="Light3D" default="0.5" />
 		<member name="shadow_bias" type="float" setter="set_param" getter="get_param" overrides="Light3D" default="0.03" />
 		<member name="shadow_normal_bias" type="float" setter="set_param" getter="get_param" overrides="Light3D" default="1.0" />
 		<member name="spot_angle" type="float" setter="set_param" getter="get_param" default="45.0">

drivers/gles3/shaders/scene.glsl

@@ -2138,7 +2138,7 @@ void main() {
 			continue;
 		}
 #endif
-		light_compute(normal, normalize(directional_lights[i].direction), normalize(view), directional_lights[i].size, directional_lights[i].color * directional_lights[i].energy, true, 1.0, f0, roughness, metallic, 1.0, albedo, alpha, screen_uv,
+		light_compute(normal, normalize(directional_lights[i].direction), normalize(view), directional_lights[i].size, directional_lights[i].color * directional_lights[i].energy, true, 1.0, f0, roughness, metallic, directional_lights[i].specular, albedo, alpha, screen_uv,
 #ifdef LIGHT_BACKLIGHT_USED
 				backlight,
 #endif
@@ -2440,7 +2440,7 @@ void main() {
 #endif // SHADOWS_DISABLED
 
 #ifndef USE_VERTEX_LIGHTING
-	light_compute(normal, normalize(directional_lights[directional_shadow_index].direction), normalize(view), directional_lights[directional_shadow_index].size, directional_lights[directional_shadow_index].color * directional_lights[directional_shadow_index].energy, true, directional_shadow, f0, roughness, metallic, 1.0, albedo, alpha, screen_uv,
+	light_compute(normal, normalize(directional_lights[directional_shadow_index].direction), normalize(view), directional_lights[directional_shadow_index].size, directional_lights[directional_shadow_index].color * directional_lights[directional_shadow_index].energy, true, directional_shadow, f0, roughness, metallic, directional_lights[directional_shadow_index].specular, albedo, alpha, screen_uv,
 #ifdef LIGHT_BACKLIGHT_USED
 			backlight,
 #endif

scene/3d/light_3d.cpp

@@ -545,7 +545,7 @@ void DirectionalLight3D::_validate_property(PropertyInfo &p_property) const {
 		p_property.usage = PROPERTY_USAGE_NO_EDITOR;
 	}
 
-	if (p_property.name == "light_size" || p_property.name == "light_projector" || p_property.name == "light_specular") {
+	if (p_property.name == "light_size" || p_property.name == "light_projector") {
 		// Not implemented in DirectionalLight3D (`light_size` is replaced by `light_angular_distance`).
 		p_property.usage = PROPERTY_USAGE_NONE;
 	}
@@ -595,6 +595,7 @@ DirectionalLight3D::DirectionalLight3D() :
 	// Increase the default shadow normal bias to better suit most scenes.
 	set_param(PARAM_SHADOW_NORMAL_BIAS, 2.0);
 	set_param(PARAM_INTENSITY, 100000.0); // Specified in Lux, approximate mid-day sun.
+	set_param(PARAM_SPECULAR, 1.0);
 	set_shadow_mode(SHADOW_PARALLEL_4_SPLITS);
 	blend_splits = false;
 	set_sky_mode(SKY_MODE_LIGHT_AND_SKY);

servers/rendering/renderer_rd/shaders/forward_clustered/scene_forward_clustered.glsl

@@ -2351,7 +2351,7 @@ void fragment_shader(in SceneData scene_data) {
 #else
 					directional_lights.data[i].color * directional_lights.data[i].energy * tint,
 #endif
-					true, shadow, f0, orms, 1.0, albedo, alpha, screen_uv,
+					true, shadow, f0, orms, directional_lights.data[i].specular, albedo, alpha, screen_uv,
 #ifdef LIGHT_BACKLIGHT_USED
 					backlight,
 #endif

servers/rendering/renderer_rd/shaders/forward_mobile/scene_forward_mobile.glsl

@@ -1647,7 +1647,7 @@ void main() {
 
 			light_compute(normal, directional_lights.data[i].direction, view, size_A,
 					directional_lights.data[i].color * directional_lights.data[i].energy * tint,
-					true, shadow, f0, orms, 1.0, albedo, alpha, screen_uv,
+					true, shadow, f0, orms, directional_lights.data[i].specular, albedo, alpha, screen_uv,
 #ifdef LIGHT_BACKLIGHT_USED
 					backlight,
 #endif