Add GLTF light import

Co-authored-by: K.S. Ernest (iFire) Lee <ernest.lee@chibifire.com>

2 files changed, 144 insertions, 6 deletions

diff --git a/editor/import/editor_scene_importer_gltf.cpp b/editor/import/editor_scene_importer_gltf.cpp
index e340f41e3b..1a232658fe 100644
--- a/editor/import/editor_scene_importer_gltf.cpp
+++ b/editor/import/editor_scene_importer_gltf.cpp
@@ -286,7 +286,16 @@ Error EditorSceneImporterGLTF::_parse_nodes(GLTFState &state) {
 			node->xform.basis.set_quat_scale(node->rotation, node->scale);
 			node->xform.origin = node->translation;
 		}
-
+		if (n.has("extensions")) {
+			Dictionary extensions = n["extensions"];
+			if (extensions.has("KHR_lights_punctual")) {
+				Dictionary lights_punctual = extensions["KHR_lights_punctual"];
+				if (lights_punctual.has("light")) {
+					GLTFLightIndex light = lights_punctual["light"];
+					node->light = light;
+				}
+			}
+		}
 		if (n.has("children")) {
 			const Array &children = n["children"];
 			for (int j = 0; j < children.size(); j++) {
@@ -2245,6 +2254,58 @@ void EditorSceneImporterGLTF::_remove_duplicate_skins(GLTFState &state) {
 	}
 }
 
+Error EditorSceneImporterGLTF::_parse_lights(GLTFState &state) {
+	if (!state.json.has("extensions")) {
+		return OK;
+	}
+	Dictionary extensions = state.json["extensions"];
+	if (!extensions.has("KHR_lights_punctual")) {
+		return OK;
+	}
+	Dictionary lights_punctual = extensions["KHR_lights_punctual"];
+	if (!lights_punctual.has("lights")) {
+		return OK;
+	}
+
+	const Array &lights = lights_punctual["lights"];
+
+	for (GLTFLightIndex light_i = 0; light_i < lights.size(); light_i++) {
+		const Dictionary &d = lights[light_i];
+
+		GLTFLight light;
+		ERR_FAIL_COND_V(!d.has("type"), ERR_PARSE_ERROR);
+		const String &type = d["type"];
+		light.type = type;
+
+		if (d.has("color")) {
+			const Array &arr = d["color"];
+			ERR_FAIL_COND_V(arr.size() != 3, ERR_PARSE_ERROR);
+			const Color c = Color(arr[0], arr[1], arr[2]).to_srgb();
+			light.color = c;
+		}
+		if (d.has("intensity")) {
+			light.intensity = d["intensity"];
+		}
+		if (d.has("range")) {
+			light.range = d["range"];
+		}
+		if (type == "spot") {
+			const Dictionary &spot = d["spot"];
+			light.inner_cone_angle = spot["innerConeAngle"];
+			light.outer_cone_angle = spot["outerConeAngle"];
+			ERR_FAIL_COND_V_MSG(light.inner_cone_angle >= light.outer_cone_angle, ERR_PARSE_ERROR, "The inner angle must be smaller than the outer angle.");
+		} else if (type != "point" && type != "directional") {
+			ERR_FAIL_V_MSG(ERR_PARSE_ERROR, "Light type is unknown.");
+		}
+
+		state.lights.push_back(light);
+	}
+
+	print_verbose("glTF: Total lights: " + itos(state.lights.size()));
+
+	return OK;
+}
+
 Error EditorSceneImporterGLTF::_parse_cameras(GLTFState &state) {
 	if (!state.json.has("cameras")) {
 		return OK;
@@ -2488,6 +2549,58 @@ MeshInstance3D *EditorSceneImporterGLTF::_generate_mesh_instance(GLTFState &stat
 	return mi;
 }
 
+Light3D *EditorSceneImporterGLTF::_generate_light(GLTFState &state, Node *scene_parent, const GLTFNodeIndex node_index) {
+	const GLTFNode *gltf_node = state.nodes[node_index];
+
+	ERR_FAIL_INDEX_V(gltf_node->light, state.lights.size(), nullptr);
+
+	print_verbose("glTF: Creating light for: " + gltf_node->name);
+
+	const GLTFLight &l = state.lights[gltf_node->light];
+
+	float intensity = l.intensity;
+	if (intensity > 10) {
+		// GLTF spec has the default around 1, but Blender defaults lights to 100.
+		// The only sane way to handle this is to check where it came from and
+		// handle it accordingly. If it's over 10, it probably came from Blender.
+		intensity /= 100;
+	}
+
+	if (l.type == "directional") {
+		DirectionalLight3D *light = memnew(DirectionalLight3D);
+		light->set_param(Light3D::PARAM_ENERGY, intensity);
+		light->set_color(l.color);
+		return light;
+	}
+
+	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;
+	if (l.type == "point") {
+		OmniLight3D *light = memnew(OmniLight3D);
+		light->set_param(OmniLight3D::PARAM_ATTENUATION, attenuation);
+		light->set_param(OmniLight3D::PARAM_RANGE, range);
+		light->set_color(l.color);
+		return light;
+	}
+	if (l.type == "spot") {
+		SpotLight3D *light = memnew(SpotLight3D);
+		light->set_param(SpotLight3D::PARAM_ATTENUATION, attenuation);
+		light->set_param(SpotLight3D::PARAM_RANGE, range);
+		light->set_param(SpotLight3D::PARAM_SPOT_ANGLE, Math::rad2deg(l.outer_cone_angle));
+		light->set_color(l.color);
+
+		// Line of best fit derived from guessing, see https://www.desmos.com/calculator/biiflubp8b
+		// The points in desmos are not exact, except for (1, infinity).
+		float angle_ratio = l.inner_cone_angle / l.outer_cone_angle;
+		float angle_attenuation = 0.2 / (1 - angle_ratio) - 0.1;
+		light->set_param(SpotLight3D::PARAM_SPOT_ATTENUATION, angle_attenuation);
+		return light;
+	}
+	return nullptr;
+}
+
 Camera3D *EditorSceneImporterGLTF::_generate_camera(GLTFState &state, Node *scene_parent, const GLTFNodeIndex node_index) {
 	const GLTFNode *gltf_node = state.nodes[node_index];
 
@@ -2561,6 +2674,8 @@ void EditorSceneImporterGLTF::_generate_scene_node(GLTFState &state, Node *scene
 			current_node = _generate_mesh_instance(state, scene_parent, node_index);
 		} else if (gltf_node->camera >= 0) {
 			current_node = _generate_camera(state, scene_parent, node_index);
+		} else if (gltf_node->light >= 0) {
+			current_node = _generate_light(state, scene_parent, node_index);
 		} else {
 			current_node = _generate_spatial(state, scene_parent, node_index);
 		}
@@ -3037,22 +3152,28 @@ Node *EditorSceneImporterGLTF::import_scene(const String &p_path, uint32_t p_fla
 		return nullptr;
 	}
 
-	/* STEP 14 PARSE CAMERAS */
+	/* STEP 14 PARSE LIGHTS */
+	err = _parse_lights(state);
+	if (err != OK) {
+		return NULL;
+	}
+
+	/* STEP 15 PARSE CAMERAS */
 	err = _parse_cameras(state);
 	if (err != OK) {
 		return nullptr;
 	}
 
-	/* STEP 15 PARSE ANIMATIONS */
+	/* STEP 16 PARSE ANIMATIONS */
 	err = _parse_animations(state);
 	if (err != OK) {
 		return nullptr;
 	}
 
-	/* STEP 16 ASSIGN SCENE NAMES */
+	/* STEP 17 ASSIGN SCENE NAMES */
 	_assign_scene_names(state);
 
-	/* STEP 17 MAKE SCENE! */
+	/* STEP 18 MAKE SCENE! */
 	Node3D *scene = _generate_scene(state, p_bake_fps);
 
 	return scene;
diff --git a/editor/import/editor_scene_importer_gltf.h b/editor/import/editor_scene_importer_gltf.h
index d45410fa57..95c6b87af5 100644
--- a/editor/import/editor_scene_importer_gltf.h
+++ b/editor/import/editor_scene_importer_gltf.h
@@ -32,6 +32,7 @@
 #define EDITOR_SCENE_IMPORTER_GLTF_H
 
 #include "editor/import/resource_importer_scene.h"
+#include "scene/3d/light_3d.h"
 #include "scene/3d/node_3d.h"
 #include "scene/3d/skeleton_3d.h"
 
@@ -50,6 +51,7 @@ class EditorSceneImporterGLTF : public EditorSceneImporter {
 	typedef int GLTFImageIndex;
 	typedef int GLTFMaterialIndex;
 	typedef int GLTFMeshIndex;
+	typedef int GLTFLightIndex;
 	typedef int GLTFNodeIndex;
 	typedef int GLTFSkeletonIndex;
 	typedef int GLTFSkinIndex;
@@ -113,6 +115,8 @@ class EditorSceneImporterGLTF : public EditorSceneImporter {
 
 		GLTFNodeIndex fake_joint_parent = -1;
 
+		GLTFLightIndex light = -1;
+
 		GLTFNode() {}
 	};
 
@@ -218,6 +222,17 @@ class EditorSceneImporterGLTF : public EditorSceneImporter {
 		GLTFCamera() {}
 	};
 
+	struct GLTFLight {
+		Color color = Color(1.0f, 1.0f, 1.0f);
+		float intensity = 1.0f;
+		String type = "";
+		float range = Math_INF;
+		float inner_cone_angle = 0.0f;
+		float outer_cone_angle = Math_PI / 4.0;
+
+		GLTFLight() {}
+	};
+
 	struct GLTFAnimation {
 		bool loop = false;
 
@@ -271,6 +286,7 @@ class EditorSceneImporterGLTF : public EditorSceneImporter {
 
 		Vector<GLTFSkin> skins;
 		Vector<GLTFCamera> cameras;
+		Vector<GLTFLight> lights;
 
 		Set<String> unique_names;
 
@@ -349,12 +365,13 @@ class EditorSceneImporterGLTF : public EditorSceneImporter {
 	void _remove_duplicate_skins(GLTFState &state);
 
 	Error _parse_cameras(GLTFState &state);
-
+	Error _parse_lights(GLTFState &state);
 	Error _parse_animations(GLTFState &state);
 
 	BoneAttachment3D *_generate_bone_attachment(GLTFState &state, Skeleton3D *skeleton, const GLTFNodeIndex node_index);
 	MeshInstance3D *_generate_mesh_instance(GLTFState &state, Node *scene_parent, const GLTFNodeIndex node_index);
 	Camera3D *_generate_camera(GLTFState &state, Node *scene_parent, const GLTFNodeIndex node_index);
+	Light3D *_generate_light(GLTFState &state, Node *scene_parent, const GLTFNodeIndex node_index);
 	Node3D *_generate_spatial(GLTFState &state, Node *scene_parent, const GLTFNodeIndex node_index);
 
 	void _generate_scene_node(GLTFState &state, Node *scene_parent, Node3D *scene_root, const GLTFNodeIndex node_index);