From ef6ef081d8e412d89b688fbc25ece6ee81e57337 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Wed, 15 Mar 2023 15:57:12 +0300
Subject: [PATCH] Support KHR_lights_punctual in gltf parser

---
 libs/gfx/include/psemek/gfx/gltf_parser.hpp | 19 ++++++
 libs/gfx/source/gltf_parser.cpp             | 72 +++++++++++++++++++++
 2 files changed, 91 insertions(+)

diff --git a/libs/gfx/include/psemek/gfx/gltf_parser.hpp b/libs/gfx/include/psemek/gfx/gltf_parser.hpp
index baeb754d..ede3613c 100644
--- a/libs/gfx/include/psemek/gfx/gltf_parser.hpp
+++ b/libs/gfx/include/psemek/gfx/gltf_parser.hpp
@@ -8,6 +8,7 @@
 #include <vector>
 #include <string>
 #include <optional>
+#include <variant>
 
 namespace psemek::gfx
 {
@@ -18,6 +19,7 @@ namespace psemek::gfx
 		{
 			std::string name;
 			std::optional<std::size_t> mesh;
+			std::optional<std::size_t> light; // KHR_lights_punctual
 			std::vector<std::size_t> children;
 
 			geom::vector<float, 3> translation;
@@ -75,6 +77,22 @@ namespace psemek::gfx
 			std::string uri;
 		};
 
+		// KHR_lights_punctual
+		struct light
+		{
+			enum
+			{
+				directional,
+				point,
+				spot,
+			} type;
+
+			gfx::color_3f color;
+			float intensity;
+			float range;
+			geom::interval<float> cone_angle;
+		};
+
 		std::vector<node> nodes;
 		std::vector<mesh> meshes;
 		std::vector<material> materials;
@@ -82,6 +100,7 @@ namespace psemek::gfx
 		std::vector<accessor> accessors;
 		std::vector<buffer_view> buffer_views;
 		std::vector<buffer> buffers;
+		std::vector<light> lights; // KHR_lights_punctual
 
 		std::unordered_map<std::string, std::size_t> node_index;
 		std::unordered_map<std::string, std::size_t> material_index;
diff --git a/libs/gfx/source/gltf_parser.cpp b/libs/gfx/source/gltf_parser.cpp
index f329bbca..73b40b52 100644
--- a/libs/gfx/source/gltf_parser.cpp
+++ b/libs/gfx/source/gltf_parser.cpp
@@ -9,6 +9,8 @@
 #include <rapidjson/document.h>
 #include <rapidjson/istreamwrapper.h>
 
+#include <unordered_set>
+
 namespace psemek::gfx
 {
 
@@ -56,6 +58,11 @@ namespace psemek::gfx
 			throw std::runtime_error(util::to_string("Unknown accessor component type: ", type));
 		}
 
+		static std::unordered_set<std::string> supported_extensions =
+		{
+			"KHR_lights_punctual",
+		};
+
 	}
 
 	gltf_asset parse_gltf(io::istream && stream)
@@ -70,6 +77,11 @@ namespace psemek::gfx
 
 		gltf_asset result;
 
+		if (document.HasMember("extensionsRequired"))
+			for (auto const & extension : document["extensionsRequired"].GetArray())
+				if (!supported_extensions.contains(extension.GetString()))
+					throw std::runtime_error("glTF extension " + std::string(extension.GetString()) + " is not supported");
+
 		for (auto const & node : document["nodes"].GetArray())
 		{
 			auto & target = result.nodes.emplace_back();
@@ -106,6 +118,15 @@ namespace psemek::gfx
 				for (auto const & child : node["children"].GetArray())
 					target.children.push_back(child.GetUint64());
 			}
+
+			if (node.HasMember("extensions"))
+				for (auto const & extension : node["extensions"].GetObject())
+				{
+					if (extension.name == "KHR_lights_punctual")
+					{
+						target.light = extension.value["light"].GetUint64();
+					}
+				}
 		}
 
 		for (auto const & mesh : document["meshes"].GetArray())
@@ -199,6 +220,57 @@ namespace psemek::gfx
 			target.uri = buffer["uri"].GetString();
 		}
 
+		if (document.HasMember("extensions"))
+			for (auto const & extension : document["extensions"].GetObject())
+			{
+				if (extension.name == "KHR_lights_punctual")
+				{
+					for (auto const & light : extension.value["lights"].GetArray())
+					{
+						auto & target = result.lights.emplace_back();
+						target.color = {1.f, 1.f, 1.f};
+						target.intensity = 1.f;
+						target.range = std::numeric_limits<float>::infinity();
+						target.cone_angle = {0.f, geom::pi / 4.f};
+
+						std::string type = light["type"].GetString();
+
+						if (type == "directional")
+							target.type = gltf_asset::light::directional;
+						else if (type == "point")
+							target.type = gltf_asset::light::point;
+						else if (type == "spot")
+							target.type = gltf_asset::light::spot;
+						else
+							throw std::runtime_error("unknown light type: " + type);
+
+						if (light.HasMember("color"))
+						{
+							auto const & color = light["color"].GetArray();
+							for (std::size_t i = 0; i < 3; ++i)
+								target.color[i] = color[i].GetFloat();
+						}
+
+						if (light.HasMember("intensity"))
+							target.intensity = light["intensity"].GetFloat();
+
+						if (light.HasMember("range"))
+							target.range = light["range"].GetFloat();
+
+						if (target.type == gltf_asset::light::spot)
+						{
+							auto const & spot = light["spot"].GetObject();
+
+							if (spot.HasMember("innerConeAngle"))
+								target.cone_angle.min = spot["innerConeAngle"].GetFloat();
+
+							if (spot.HasMember("outerConeAngle"))
+								target.cone_angle.max = spot["outerConeAngle"].GetFloat();
+						}
+					}
+				}
+			}
+
 		for (std::size_t i = 0; i < result.nodes.size(); ++i)
 			result.node_index[result.nodes[i].name] = i;