Fix gltf static mesh loading issues (#14)

* Support u8 / u32 indices

* Skip primitives without vertices

* Add support for non-indexed geometry & skipping primitives

* Fix possible memory leak on error

* Use SSkinnedMesh

* Check indices

* Properly mirror node hierarchy

* Update .gitignore

* Reorder includes

* Add some throws for logic errors

* Fix non-indexed geometry winding order, add unit test

* Address code review comments

* Add matrix transform unit test

.gitignore

@@ -23,3 +23,15 @@ scripts/glext.h
 
 # vscode cmake plugin
 build/*
+
+# vscode clangd plugin
+.cache
+compile_commands.json
+
+# build dependencies
+_deps
+
+# autogenerated test-related files
+**/CTestTestfile.cmake
+Testing
+DartConfiguration.tcl

include/SSkinMeshBuffer.h

@@ -301,7 +301,31 @@ struct SSkinMeshBuffer : public IMeshBuffer
 	}
 
 	//! append the vertices and indices to the current buffer
-	void append(const void *const vertices, u32 numVertices, const u16 *const indices, u32 numIndices) override {}
+	void append(const void* const vertices, u32 numVertices, const u16* const indices, u32 numIndices) override {
+		if (vertices == getVertices())
+			throw std::logic_error("can't append own vertices");
+
+		if (VertexType != video::EVT_STANDARD)
+			throw std::logic_error("invalid vertex type");
+
+		const u32 prevVertexCount = getVertexCount();
+
+		Vertices_Standard.reallocate(prevVertexCount + numVertices);
+		for (u32 i=0; i < numVertices; ++i) {
+			Vertices_Standard.push_back(static_cast<const video::S3DVertex* const>(vertices)[i]);
+			BoundingBox.addInternalPoint(static_cast<const video::S3DVertex* const>(vertices)[i].Pos);
+		}
+
+		Indices.reallocate(getIndexCount() + numIndices);
+		for (u32 i=0; i < numIndices; ++i) {
+			Indices.push_back(indices[i] + prevVertexCount);
+		}
+	}
+
+	//! NOT IMPLEMENTED YET: append the meshbuffer to the current buffer
+	void append(const IMeshBuffer* const other) override {
+		throw std::logic_error("not implemented yet");
+	}
 
 	//! get the current hardware mapping hint for vertex buffers
 	E_HARDWARE_MAPPING getHardwareMappingHint_Vertex() const override

source/Irrlicht/CGLTFMeshFileLoader.cpp

@@ -1,23 +1,25 @@
 #include "CGLTFMeshFileLoader.h"
-#include "CMeshBuffer.h"
+
 #include "coreutil.h"
-#include "IAnimatedMesh.h"
-#include "ILogger.h"
-#include "IReadFile.h"
+#include "CSkinnedMesh.h"
+#include "ISkinnedMesh.h"
 #include "irrTypes.h"
-#include "os.h"
+#include "IReadFile.h"
+#include "matrix4.h"
 #include "path.h"
 #include "S3DVertex.h"
-#include "SAnimatedMesh.h"
-#include "SColor.h"
-#include "SMesh.h"
+#include "quaternion.h"
 #include "vector3d.h"
+
+#include "tiniergltf.hpp"
+
+#include <array>
 #include <cstddef>
 #include <cstring>
+#include <limits>
 #include <memory>
 #include <optional>
 #include <stdexcept>
-#include <string>
 #include <utility>
 #include <variant>
 #include <vector>
@@ -96,72 +98,214 @@ IAnimatedMesh* CGLTFMeshFileLoader::createMesh(io::IReadFile* file)
 		return nullptr;
 	}
 
-	MeshExtractor parser(std::move(model.value()));
-	SMesh* baseMesh(new SMesh {});
-	loadPrimitives(parser, baseMesh);
-
-	SAnimatedMesh* animatedMesh(new SAnimatedMesh {});
-	animatedMesh->addMesh(baseMesh);
-	baseMesh->drop();
-
-	return animatedMesh;
+	ISkinnedMesh *mesh = new CSkinnedMesh();
+	MeshExtractor parser(std::move(model.value()), mesh);
+	try {
+		parser.loadNodes();
+	} catch (std::runtime_error &e) {
+		mesh->drop();
+		return nullptr;
+	}
+	return mesh;
 }
 
+static void transformVertices(std::vector<video::S3DVertex> &vertices, const core::matrix4 &transform)
+{
+	for (auto &vertex : vertices) {
+		// Apply scaling, rotation and rotation (in that order) to the position.
+		transform.transformVect(vertex.Pos);
+		// For the normal, we do not want to apply the translation.
+		// TODO note that this also applies scaling; the Irrlicht method is misnamed.
+		transform.rotateVect(vertex.Normal);
+		// Renormalize (length might have been affected by scaling).
+		vertex.Normal.normalize();
+	}
+}
+
+static void checkIndices(const std::vector<u16> &indices, const std::size_t nVerts)
+{
+	for (u16 index : indices) {
+		if (index >= nVerts)
+			throw std::runtime_error("index out of bounds");
+	}
+}
+
+static std::vector<u16> generateIndices(const std::size_t nVerts)
+{
+	std::vector<u16> indices(nVerts);
+	for (std::size_t i = 0; i < nVerts; i += 3) {
+		// Reverse winding order per triangle
+		indices[i] = i + 2;
+		indices[i + 1] = i + 1;
+		indices[i + 2] = i;
+	}
+	return indices;
+}
 
 /**
  * Load up the rawest form of the model. The vertex positions and indices.
  * Documentation: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#meshes
  * If material is undefined, then a default material MUST be used.
 */
-void CGLTFMeshFileLoader::loadPrimitives(
-		const MeshExtractor& parser,
-		SMesh* mesh)
+void CGLTFMeshFileLoader::MeshExtractor::loadMesh(
+		const std::size_t meshIdx,
+		ISkinnedMesh::SJoint *parent) const
 {
-	for (std::size_t i = 0; i < parser.getMeshCount(); ++i) {
-		for (std::size_t j = 0; j < parser.getPrimitiveCount(i); ++j) {
-			auto indices = parser.getIndices(i, j);
-			auto vertices = parser.getVertices(i, j);
+	for (std::size_t j = 0; j < getPrimitiveCount(meshIdx); ++j) {
+		auto vertices = getVertices(meshIdx, j);
+		if (!vertices.has_value())
+			continue; // "When positions are not specified, client implementations SHOULD skip primitive’s rendering"
 
-			SMeshBuffer* meshbuf(new SMeshBuffer {});
-			meshbuf->append(vertices.data(), vertices.size(),
-				indices.data(), indices.size());
-			mesh->addMeshBuffer(meshbuf);
-			meshbuf->drop();
+		// Excludes the max value for consistency.
+		if (vertices->size() >= std::numeric_limits<u16>::max())
+			throw std::runtime_error("too many vertices");
+
+		// Apply the global transform along the parent chain.
+		transformVertices(*vertices, parent->GlobalMatrix);
+		
+		auto maybeIndices = getIndices(meshIdx, j);
+		std::vector<u16> indices;
+		if (maybeIndices.has_value()) {
+			indices = std::move(*maybeIndices);
+			checkIndices(indices, vertices->size());
+		} else {
+			// Non-indexed geometry
+			indices = generateIndices(vertices->size());
+		}
+
+		auto *meshbuf = m_irr_model->addMeshBuffer();
+		meshbuf->append(vertices->data(), vertices->size(),
+			indices.data(), indices.size());
+	}
+}
+
+// Base transformation between left & right handed coordinate systems.
+// This just inverts the Z axis.
+static core::matrix4 leftToRight = core::matrix4(
+	1, 0, 0, 0,
+	0, 1, 0, 0,
+	0, 0, -1, 0,
+	0, 0, 0, 1
+);
+static core::matrix4 rightToLeft = leftToRight;
+
+static core::matrix4 loadTransform(const tiniergltf::Node::Matrix &m)
+{
+	// Note: Under the hood, this casts these doubles to floats.
+	return core::matrix4(
+			m[0], m[1], m[2], m[3],
+			m[4], m[5], m[6], m[7],
+			m[8], m[9], m[10], m[11],
+			m[12], m[13], m[14], m[15]);
+}
+
+static core::matrix4 loadTransform(const tiniergltf::Node::TRS &trs)
+{
+	const auto &trans = trs.translation;
+	const auto &rot = trs.rotation;
+	const auto &scale = trs.scale;
+	core::matrix4 transMat;
+	transMat.setTranslation(core::vector3df(trans[0], trans[1], trans[2]));
+	core::matrix4 rotMat = core::quaternion(rot[0], rot[1], rot[2], rot[3]).getMatrix();
+	core::matrix4 scaleMat;
+	scaleMat.setScale(core::vector3df(scale[0], scale[1], scale[2]));
+	return transMat * rotMat * scaleMat;
+}
+
+static core::matrix4 loadTransform(std::optional<std::variant<tiniergltf::Node::Matrix, tiniergltf::Node::TRS>> transform) {
+	if (!transform.has_value()) {
+		return core::matrix4();
+	}
+	core::matrix4 mat = std::visit([](const auto &t) { return loadTransform(t); }, *transform);
+	return rightToLeft * mat * leftToRight;
+}
+
+void CGLTFMeshFileLoader::MeshExtractor::loadNode(
+		const std::size_t nodeIdx,
+		ISkinnedMesh::SJoint *parent) const
+{
+	const auto &node = m_gltf_model.nodes->at(nodeIdx);
+	auto *joint = m_irr_model->addJoint(parent);
+	const core::matrix4 transform = loadTransform(node.transform);
+	joint->LocalMatrix = transform;
+	joint->GlobalMatrix = parent ? parent->GlobalMatrix * joint->LocalMatrix : joint->LocalMatrix;
+	if (node.name.has_value()) {
+		joint->Name = node.name->c_str();
+	}
+	if (node.mesh.has_value()) {
+		loadMesh(*node.mesh, joint);
+	}
+	if (node.children.has_value()) {
+		for (const auto &child : *node.children) {
+			loadNode(child, joint);
 		}
 	}
 }
 
-CGLTFMeshFileLoader::MeshExtractor::MeshExtractor(
-		const tiniergltf::GlTF& model) noexcept
-	: m_model(model)
-{
-}
-
-CGLTFMeshFileLoader::MeshExtractor::MeshExtractor(
-		const tiniergltf::GlTF&& model) noexcept
-	: m_model(model)
+void CGLTFMeshFileLoader::MeshExtractor::loadNodes() const
 {
+	std::vector<bool> isChild(m_gltf_model.nodes->size());
+	for (const auto &node : *m_gltf_model.nodes) {
+		if (!node.children.has_value())
+			continue;
+		for (const auto &child : *node.children) {
+			isChild[child] = true;
+		}
+	}
+	// Load all nodes that aren't children.
+	// Children will be loaded by their parent nodes.
+	for (std::size_t i = 0; i < m_gltf_model.nodes->size(); ++i) {
+		if (!isChild[i]) {
+			loadNode(i, nullptr);
+		}
+	}
 }
 
 /**
  * Extracts GLTF mesh indices into the irrlicht model.
 */
-std::vector<u16> CGLTFMeshFileLoader::MeshExtractor::getIndices(
+std::optional<std::vector<u16>> CGLTFMeshFileLoader::MeshExtractor::getIndices(
 		const std::size_t meshIdx,
 		const std::size_t primitiveIdx) const
 {
-	// FIXME this need not exist. What do we do if it doesn't?
 	const auto accessorIdx = getIndicesAccessorIdx(meshIdx, primitiveIdx);
+	if (!accessorIdx.has_value())
+		return std::nullopt; // non-indexed geometry
+	const auto &accessor = m_gltf_model.accessors->at(accessorIdx.value());
 	
 	const auto& buf = getBuffer(accessorIdx.value());
 
-	// FIXME check accessor type (which could also be u8 or u32).
 	std::vector<u16> indices{};
 	const auto count = getElemCount(accessorIdx.value());
 	for (std::size_t i = 0; i < count; ++i) {
-		std::size_t elemIdx = count - i - 1;
-		indices.push_back(readPrimitive<u16>(
-			BufferOffset(buf, elemIdx * sizeof(u16))));
+		std::size_t elemIdx = count - i - 1; // reverse index order
+		u16 index;
+		// Note: glTF forbids the max value for each component type.
+		switch (accessor.componentType) {
+			case tiniergltf::Accessor::ComponentType::UNSIGNED_BYTE: {
+				index = readPrimitive<u8>(BufferOffset(buf, elemIdx * sizeof(u8)));
+				if (index == std::numeric_limits<u8>::max())
+					throw std::runtime_error("invalid index");
+				break;
+			}
+			case tiniergltf::Accessor::ComponentType::UNSIGNED_SHORT: {
+				index = readPrimitive<u16>(BufferOffset(buf, elemIdx * sizeof(u16)));
+				if (index == std::numeric_limits<u16>::max())
+					throw std::runtime_error("invalid index");
+				break;
+			}
+			case tiniergltf::Accessor::ComponentType::UNSIGNED_INT: {
+				u32 indexWide = readPrimitive<u32>(BufferOffset(buf, elemIdx * sizeof(u32)));
+				// Use >= here for consistency.
+				if (indexWide >= std::numeric_limits<u16>::max())
+					throw std::runtime_error("index too large (>= 65536)");
+				index = static_cast<u16>(indexWide);
+				break;
+			}
+			default:
+				throw std::runtime_error("invalid index component type");
+		}
+		indices.push_back(index);
 	}
 
 	return indices;
@@ -170,15 +314,20 @@ std::vector<u16> CGLTFMeshFileLoader::MeshExtractor::getIndices(
 /**
  * Create a vector of video::S3DVertex (model data) from a mesh & primitive index.
 */
-std::vector<video::S3DVertex> CGLTFMeshFileLoader::MeshExtractor::getVertices(
+std::optional<std::vector<video::S3DVertex>> CGLTFMeshFileLoader::MeshExtractor::getVertices(
 		const std::size_t meshIdx,
 		const std::size_t primitiveIdx) const
 {
 	const auto positionAccessorIdx = getPositionAccessorIdx(
 			meshIdx, primitiveIdx);
+	if (!positionAccessorIdx.has_value()) {
+		// "When positions are not specified, client implementations SHOULD skip primitive's rendering"
+		return std::nullopt;
+	}
+
 	std::vector<vertex_t> vertices{};
-	vertices.resize(getElemCount(positionAccessorIdx));
-	copyPositions(positionAccessorIdx, vertices);
+	vertices.resize(getElemCount(*positionAccessorIdx));
+	copyPositions(*positionAccessorIdx, vertices);
 
 	const auto normalAccessorIdx = getNormalAccessorIdx(
 			meshIdx, primitiveIdx);
@@ -200,7 +349,7 @@ std::vector<video::S3DVertex> CGLTFMeshFileLoader::MeshExtractor::getVertices(
 */
 std::size_t CGLTFMeshFileLoader::MeshExtractor::getMeshCount() const
 {
-	return m_model.meshes->size();
+	return m_gltf_model.meshes->size();
 }
 
 /**
@@ -209,7 +358,7 @@ std::size_t CGLTFMeshFileLoader::MeshExtractor::getMeshCount() const
 std::size_t CGLTFMeshFileLoader::MeshExtractor::getPrimitiveCount(
 		const std::size_t meshIdx) const
 {
-	return m_model.meshes->at(meshIdx).primitives.size();
+	return m_gltf_model.meshes->at(meshIdx).primitives.size();
 }
 
 /**
@@ -246,6 +395,7 @@ core::vector2df CGLTFMeshFileLoader::MeshExtractor::readVec2DF(
 
 /**
  * Read a vector3df from a buffer at an offset.
+ * Also does right-to-left-handed coordinate system conversion (inverts Z axis).
  * @return vec3 core::Vector3df
 */
 core::vector3df CGLTFMeshFileLoader::MeshExtractor::readVec3DF(
@@ -253,9 +403,9 @@ core::vector3df CGLTFMeshFileLoader::MeshExtractor::readVec3DF(
 		const core::vector3df scale = {1.0f,1.0f,1.0f})
 {
 	return core::vector3df(
-		scale.X * readPrimitive<float>(readFrom),
-		scale.Y * readPrimitive<float>(BufferOffset(readFrom, sizeof(float))),
-		-scale.Z * readPrimitive<float>(BufferOffset(readFrom, 2 *
+		readPrimitive<float>(readFrom),
+		readPrimitive<float>(BufferOffset(readFrom, sizeof(float))),
+		-readPrimitive<float>(BufferOffset(readFrom, 2 *
 		sizeof(float))));
 }
 
@@ -273,8 +423,7 @@ void CGLTFMeshFileLoader::MeshExtractor::copyPositions(
 	const auto byteStride = getByteStride(accessorIdx);
 
 	for (std::size_t i = 0; i < count; i++) {
-		const auto v = readVec3DF(BufferOffset(buffer,
-			(byteStride * i)), getScale());
+		const auto v = readVec3DF(BufferOffset(buffer, byteStride * i));
 		vertices[i].Pos = v;
 	}
 }
@@ -316,29 +465,6 @@ void CGLTFMeshFileLoader::MeshExtractor::copyTCoords(
 	}
 }
 
-/**
- * Gets the scale of a model's node via a reference Vector3df.
- * Documentation: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-node
- * Type: number[3] (tinygltf: vector<double>)
- * Required: NO
- * @returns: core::vector2df
-*/
-core::vector3df CGLTFMeshFileLoader::MeshExtractor::getScale() const
-{
-	core::vector3df buffer{1.0f,1.0f,1.0f};
-	// FIXME this just checks the first node
-	const auto &node = m_model.nodes->at(0);
-	// FIXME this does not take the matrix into account
-	// (fix: properly map glTF -> Irrlicht node hierarchy)
-	if (std::holds_alternative<tiniergltf::Node::TRS>(node.transform)) {
-		const auto &trs = std::get<tiniergltf::Node::TRS>(node.transform);
-		buffer.X = static_cast<float>(trs.scale[0]);
-		buffer.Y = static_cast<float>(trs.scale[1]);
-		buffer.Z = static_cast<float>(trs.scale[2]);
-	}
-	return buffer;
-}
-
 /**
  * The number of elements referenced by this accessor, not to be confused with the number of bytes or number of components.
  * Documentation: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#_accessor_count
@@ -348,7 +474,7 @@ core::vector3df CGLTFMeshFileLoader::MeshExtractor::getScale() const
 std::size_t CGLTFMeshFileLoader::MeshExtractor::getElemCount(
 		const std::size_t accessorIdx) const
 {
-	return m_model.accessors->at(accessorIdx).count;
+	return m_gltf_model.accessors->at(accessorIdx).count;
 }
 
 /**
@@ -361,9 +487,9 @@ std::size_t CGLTFMeshFileLoader::MeshExtractor::getElemCount(
 std::size_t CGLTFMeshFileLoader::MeshExtractor::getByteStride(
 		const std::size_t accessorIdx) const
 {
-	const auto& accessor = m_model.accessors->at(accessorIdx);
+	const auto& accessor = m_gltf_model.accessors->at(accessorIdx);
 	// FIXME this does not work with sparse / zero-initialized accessors
-	const auto& view = m_model.bufferViews->at(accessor.bufferView.value());
+	const auto& view = m_gltf_model.bufferViews->at(accessor.bufferView.value());
 	return view.byteStride.value_or(accessor.elementSize());
 }
 
@@ -377,7 +503,7 @@ std::size_t CGLTFMeshFileLoader::MeshExtractor::getByteStride(
 bool CGLTFMeshFileLoader::MeshExtractor::isAccessorNormalized(
 	const std::size_t accessorIdx) const
 {
-	const auto& accessor = m_model.accessors->at(accessorIdx);
+	const auto& accessor = m_gltf_model.accessors->at(accessorIdx);
 	return accessor.normalized;
 }
 
@@ -388,10 +514,10 @@ bool CGLTFMeshFileLoader::MeshExtractor::isAccessorNormalized(
 CGLTFMeshFileLoader::BufferOffset CGLTFMeshFileLoader::MeshExtractor::getBuffer(
 		const std::size_t accessorIdx) const
 {
-	const auto& accessor = m_model.accessors->at(accessorIdx);
+	const auto& accessor = m_gltf_model.accessors->at(accessorIdx);
 	// FIXME this does not work with sparse / zero-initialized accessors
-	const auto& view = m_model.bufferViews->at(accessor.bufferView.value());
-	const auto& buffer = m_model.buffers->at(view.buffer);
+	const auto& view = m_gltf_model.bufferViews->at(accessor.bufferView.value());
+	const auto& buffer = m_gltf_model.buffers->at(view.buffer);
 
 	return BufferOffset(buffer.data, view.byteOffset);
 }
@@ -408,23 +534,19 @@ std::optional<std::size_t> CGLTFMeshFileLoader::MeshExtractor::getIndicesAccesso
 		const std::size_t meshIdx,
 		const std::size_t primitiveIdx) const
 {
-	return m_model.meshes->at(meshIdx).primitives[primitiveIdx].indices;
+	return m_gltf_model.meshes->at(meshIdx).primitives[primitiveIdx].indices;
 }
 
 /**
  * The index of the accessor that contains the POSITIONs.
  * Documentation: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#meshes-overview
  * Type: VEC3 (Float)
- * ! Required: YES (Appears so, needs another pair of eyes to research.)
- * Second pair of eyes says: "When positions are not specified, client implementations SHOULD skip primitive’s rendering"
 */
-std::size_t CGLTFMeshFileLoader::MeshExtractor::getPositionAccessorIdx(
+std::optional<std::size_t> CGLTFMeshFileLoader::MeshExtractor::getPositionAccessorIdx(
 		const std::size_t meshIdx,
 		const std::size_t primitiveIdx) const
 {
-	// FIXME position-less primitives should be skipped.
-	return m_model.meshes->at(meshIdx).primitives[primitiveIdx]
-		.attributes.position.value();
+	return m_gltf_model.meshes->at(meshIdx).primitives[primitiveIdx].attributes.position;
 }
 
 /**
@@ -437,7 +559,7 @@ std::optional<std::size_t> CGLTFMeshFileLoader::MeshExtractor::getNormalAccessor
 		const std::size_t meshIdx,
 		const std::size_t primitiveIdx) const
 {
-	return m_model.meshes->at(meshIdx).primitives[primitiveIdx].attributes.normal;
+	return m_gltf_model.meshes->at(meshIdx).primitives[primitiveIdx].attributes.normal;
 }
 
 /**
@@ -450,7 +572,7 @@ std::optional<std::size_t> CGLTFMeshFileLoader::MeshExtractor::getTCoordAccessor
 		const std::size_t meshIdx,
 		const std::size_t primitiveIdx) const
 {
-	const auto& texcoords = m_model.meshes->at(meshIdx).primitives[primitiveIdx].attributes.texcoord;
+	const auto& texcoords = m_gltf_model.meshes->at(meshIdx).primitives[primitiveIdx].attributes.texcoord;
 	if (!texcoords.has_value())
 		return std::nullopt;
 	return texcoords->at(0);

source/Irrlicht/CGLTFMeshFileLoader.h

@@ -1,13 +1,12 @@
 #ifndef __C_GLTF_MESH_FILE_LOADER_INCLUDED__
 #define __C_GLTF_MESH_FILE_LOADER_INCLUDED__
 
-#include "IAnimatedMesh.h"
+#include "ISkinnedMesh.h"
 #include "IMeshLoader.h"
 #include "IReadFile.h"
 #include "irrTypes.h"
 #include "path.h"
 #include "S3DVertex.h"
-#include "SMesh.h"
 #include "vector2d.h"
 #include "vector3d.h"
 
@@ -52,26 +51,33 @@ private:
 	public:
 		using vertex_t = video::S3DVertex;
 
-		MeshExtractor(const tiniergltf::GlTF& model) noexcept;
+		MeshExtractor(const tiniergltf::GlTF &model,
+				ISkinnedMesh *mesh) noexcept
+			: m_gltf_model(model), m_irr_model(mesh) {};
 
-		MeshExtractor(const tiniergltf::GlTF&& model) noexcept;
+		MeshExtractor(const tiniergltf::GlTF &&model,
+				ISkinnedMesh *mesh) noexcept
+			: m_gltf_model(model), m_irr_model(mesh) {};
 
 		/* Gets indices for the given mesh/primitive.
 		 *
 		 * Values are return in Irrlicht winding order.
 		 */
-		std::vector<u16> getIndices(const std::size_t meshIdx,
+		std::optional<std::vector<u16>> getIndices(const std::size_t meshIdx,
 				const std::size_t primitiveIdx) const;
 
-		std::vector<vertex_t> getVertices(std::size_t meshIdx,
+		std::optional<std::vector<vertex_t>> getVertices(std::size_t meshIdx,
 				const std::size_t primitiveIdx) const;
 
 		std::size_t getMeshCount() const;
 
 		std::size_t getPrimitiveCount(const std::size_t meshIdx) const;
 
+		void loadNodes() const;
+
 	private:
-		tiniergltf::GlTF m_model;
+		const tiniergltf::GlTF m_gltf_model;
+		ISkinnedMesh *m_irr_model;
 
 		template <typename T>
 		static T readPrimitive(const BufferOffset& readFrom);
@@ -96,12 +102,6 @@ private:
 		void copyTCoords(const std::size_t accessorIdx,
 				std::vector<vertex_t>& vertices) const;
 
-		/* Get the scale factor from the glTF mesh information.
-		 *
-		 * Returns vec3(1.0, 1.0, 1.0) if no scale factor is present.
-		 */
-		core::vector3df getScale() const;
-
 		std::size_t getElemCount(const std::size_t accessorIdx) const;
 
 		std::size_t getByteStride(const std::size_t accessorIdx) const;
@@ -113,7 +113,7 @@ private:
 		std::optional<std::size_t> getIndicesAccessorIdx(const std::size_t meshIdx,
 				const std::size_t primitiveIdx) const;
 
-		std::size_t getPositionAccessorIdx(const std::size_t meshIdx,
+		std::optional<std::size_t> getPositionAccessorIdx(const std::size_t meshIdx,
 				const std::size_t primitiveIdx) const;
 
 		/* Get the accessor id of the normals of a primitive.
@@ -125,9 +125,15 @@ private:
 		 */
 		std::optional<std::size_t> getTCoordAccessorIdx(const std::size_t meshIdx,
 				const std::size_t primitiveIdx) const;
-	};
+		
+		void loadMesh(
+			std::size_t meshIdx,
+			ISkinnedMesh::SJoint *parentJoint) const;
 
-	void loadPrimitives(const MeshExtractor& parser, SMesh* mesh);
+		void loadNode(
+			const std::size_t nodeIdx,
+			ISkinnedMesh::SJoint *parentJoint) const;
+	};
 
 	std::optional<tiniergltf::GlTF> tryParseGLTF(io::IReadFile* file);
 };

source/Irrlicht/tests/assets/blender_cube_matrix_transform.gltf

@@ -0,0 +1,106 @@
+{
+    "asset" : {
+        "generator" : "Khronos glTF Blender I/O v1.7.33",
+        "version" : "2.0"
+    },
+    "scene" : 0,
+    "scenes" : [
+        {
+            "name" : "Scene",
+            "nodes" : [
+                0
+            ]
+        }
+    ],
+    "nodes" : [
+        {
+            "mesh" : 0,
+            "name" : "Cube",
+            "matrix" : [
+				1, 0, 0, 0,
+				0, 2, 0, 0,
+				0, 0, 3, 0,
+				4, 5, 6, 1
+			]
+        }
+    ],
+    "meshes" : [
+        {
+            "name" : "Cube.004",
+            "primitives" : [
+                {
+                    "attributes" : {
+                        "POSITION" : 0,
+                        "NORMAL" : 1,
+                        "TEXCOORD_0" : 2
+                    },
+                    "indices" : 3
+                }
+            ]
+        }
+    ],
+    "accessors" : [
+        {
+            "bufferView" : 0,
+            "componentType" : 5126,
+            "count" : 24,
+            "max" : [
+                1,
+                1,
+                1
+            ],
+            "min" : [
+                -1,
+                -1,
+                -1
+            ],
+            "type" : "VEC3"
+        },
+        {
+            "bufferView" : 1,
+            "componentType" : 5126,
+            "count" : 24,
+            "type" : "VEC3"
+        },
+        {
+            "bufferView" : 2,
+            "componentType" : 5126,
+            "count" : 24,
+            "type" : "VEC2"
+        },
+        {
+            "bufferView" : 3,
+            "componentType" : 5123,
+            "count" : 36,
+            "type" : "SCALAR"
+        }
+    ],
+    "bufferViews" : [
+        {
+            "buffer" : 0,
+            "byteLength" : 288,
+            "byteOffset" : 0
+        },
+        {
+            "buffer" : 0,
+            "byteLength" : 288,
+            "byteOffset" : 288
+        },
+        {
+            "buffer" : 0,
+            "byteLength" : 192,
+            "byteOffset" : 576
+        },
+        {
+            "buffer" : 0,
+            "byteLength" : 72,
+            "byteOffset" : 768
+        }
+    ],
+    "buffers" : [
+        {
+            "byteLength" : 840,
+            "uri" : "data:application/octet-stream;base64,AACAvwAAgL8AAIA/AACAvwAAgL8AAIA/AACAvwAAgL8AAIA/AACAvwAAgD8AAIA/AACAvwAAgD8AAIA/AACAvwAAgD8AAIA/AACAvwAAgL8AAIC/AACAvwAAgL8AAIC/AACAvwAAgL8AAIC/AACAvwAAgD8AAIC/AACAvwAAgD8AAIC/AACAvwAAgD8AAIC/AACAPwAAgL8AAIA/AACAPwAAgL8AAIA/AACAPwAAgL8AAIA/AACAPwAAgD8AAIA/AACAPwAAgD8AAIA/AACAPwAAgD8AAIA/AACAPwAAgL8AAIC/AACAPwAAgL8AAIC/AACAPwAAgL8AAIC/AACAPwAAgD8AAIC/AACAPwAAgD8AAIC/AACAPwAAgD8AAIC/AACAvwAAAAAAAACAAAAAAAAAgL8AAACAAAAAAAAAAAAAAIA/AACAvwAAAAAAAACAAAAAAAAAAAAAAIA/AAAAAAAAgD8AAACAAACAvwAAAAAAAACAAAAAAAAAgL8AAACAAAAAAAAAAAAAAIC/AACAvwAAAAAAAACAAAAAAAAAAAAAAIC/AAAAAAAAgD8AAACAAAAAAAAAgL8AAACAAAAAAAAAAAAAAIA/AACAPwAAAAAAAACAAAAAAAAAAAAAAIA/AAAAAAAAgD8AAACAAACAPwAAAAAAAACAAAAAAAAAgL8AAACAAAAAAAAAAAAAAIC/AACAPwAAAAAAAACAAAAAAAAAAAAAAIC/AAAAAAAAgD8AAACAAACAPwAAAAAAAACAAADAPgAAgD8AAAA+AACAPgAAwD4AAAAAAAAgPwAAgD8AACA/AAAAAAAAYD8AAIA+AADAPgAAQD8AAAA+AAAAPwAAwD4AAEA/AAAgPwAAQD8AACA/AABAPwAAYD8AAAA/AADAPgAAgD4AAMA+AACAPgAAwD4AAIA+AAAgPwAAgD4AACA/AACAPgAAID8AAIA+AADAPgAAAD8AAMA+AAAAPwAAwD4AAAA/AAAgPwAAAD8AACA/AAAAPwAAID8AAAA/AAADAAkAAAAJAAYACAAKABUACAAVABMAFAAXABEAFAARAA4ADQAPAAQADQAEAAIABwASAAwABwAMAAEAFgALAAUAFgAFABAA"
+        }
+    ]
+}

source/Irrlicht/tests/assets/triangle_without_indices.gltf

@@ -0,0 +1,54 @@
+{
+  "scene" : 0,
+  "scenes" : [
+    {
+      "nodes" : [ 0 ]
+    }
+  ],
+  
+  "nodes" : [
+    {
+      "mesh" : 0
+    }
+  ],
+
+  "meshes" : [
+    {
+      "primitives" : [ {
+        "attributes" : {
+          "POSITION" : 0
+        }
+      } ]
+    }
+  ],
+
+  "buffers" : [
+    {
+      "uri" : "data:application/octet-stream;base64,AAAAAAAAAAAAAAAAAACAPwAAAAAAAAAAAAAAAAAAgD8AAAAA",
+      "byteLength" : 36
+    }
+  ],
+  "bufferViews" : [
+    {
+      "buffer" : 0,
+      "byteOffset" : 0,
+      "byteLength" : 36,
+      "target" : 34962
+    }
+  ],
+  "accessors" : [
+    {
+      "bufferView" : 0,
+      "byteOffset" : 0,
+      "componentType" : 5126,
+      "count" : 3,
+      "type" : "VEC3",
+      "max" : [ 1.0, 1.0, 0.0 ],
+      "min" : [ 0.0, 0.0, 0.0 ]
+    }
+  ],
+  
+  "asset" : {
+    "version" : "2.0"
+  }
+}

source/Irrlicht/tests/testCGLTFMeshFileLoader.cpp

@@ -1,4 +1,5 @@
 #include "CReadFile.h"
+#include "vector3d.h"
 
 #include <irrlicht.h>
 
@@ -54,8 +55,10 @@ TEST_CASE("load empty gltf file") {
 
 TEST_CASE("minimal triangle") {
 	auto path = GENERATE(
-		"source/Irrlicht/tests/assets/minimal_triangle.gltf",
-		"source/Irrlicht/tests/assets/triangle_with_vertex_stride.gltf");
+			"source/Irrlicht/tests/assets/minimal_triangle.gltf",
+			"source/Irrlicht/tests/assets/triangle_with_vertex_stride.gltf",
+			// Test non-indexed geometry.
+			"source/Irrlicht/tests/assets/triangle_without_indices.gltf");
 	INFO(path);
 	ScopedMesh sm(path);
 	REQUIRE(sm.getMesh() != nullptr);
@@ -164,6 +167,32 @@ TEST_CASE("blender cube scaled") {
 	}
 }
 
+TEST_CASE("blender cube matrix transform") {
+	ScopedMesh sm("source/Irrlicht/tests/assets/blender_cube_matrix_transform.gltf");
+	REQUIRE(sm.getMesh() != nullptr);
+	REQUIRE(sm.getMesh()->getMeshBufferCount() == 1);
+	
+	SECTION("Transformation is correct") {
+		REQUIRE(sm.getMesh()->getMeshBuffer(0)->getVertexCount() == 24);
+		const auto* vertices = reinterpret_cast<irr::video::S3DVertex*>(
+			sm.getMesh()->getMeshBuffer(0)->getVertices());
+		const auto checkVertex = [&](const std::size_t i, irr::core::vector3df vec) {
+			// The transform scales by (1, 2, 3) and translates by (4, 5, 6).
+			CHECK(vertices[i].Pos == vec * irr::core::vector3df{1, 2, 3}
+					// The -6 is due to the coordinate system conversion.
+					+ irr::core::vector3df{4, 5, -6});
+		};
+		checkVertex(0, irr::core::vector3df{-1, -1, -1});
+		checkVertex(3, irr::core::vector3df{-1, 1, -1});
+		checkVertex(6, irr::core::vector3df{-1, -1, 1});
+		checkVertex(9, irr::core::vector3df{-1, 1, 1});
+		checkVertex(12, irr::core::vector3df{1, -1, -1});
+		checkVertex(15, irr::core::vector3df{1, 1, -1});
+		checkVertex(18, irr::core::vector3df{1, -1, 1});
+		checkVertex(21, irr::core::vector3df{1, 1, 1});
+	}
+}
+
 TEST_CASE("snow man") {
 	ScopedMesh sm("source/Irrlicht/tests/assets/snow_man.gltf");
 	REQUIRE(sm.getMesh() != nullptr);