131 lines
2.9 KiB
Markdown
131 lines
2.9 KiB
Markdown
# NanoSG
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Simple, minimal and header-only scene graph library for NanoRT.
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NanoSG itself shoud be compiled with C++-03 compiler, but demo code uses C++11 features.
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## Build
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### Linux or macOS
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```bash
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premake5 gmake
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make
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```
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### Windows
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```bash
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premake5 vs2015
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```
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## Data structure
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### Node
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Node represents scene graph node. Tansformation node or Mesh(shape) node.
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Node is interpreted as transformation node when passing `nullptr` to Node class constructure.
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Node can contain multiple children.
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### Scene
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Scene contains root nodes and provides the method to find an intersection of nodes.
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## User defined data structure
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Following are required in user application.
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### Mesh class
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Current example code assumes mesh is all composed of triangle meshes.
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Following method must be implemented for `Scene::Traversal`.
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```cpp
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///
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/// Get the geometric normal and the shading normal at `face_idx' th face.
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///
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template<typename T>
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void GetNormal(T Ng[3], T Ns[3], const unsigned int face_idx, const T u, const T v) const;
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```
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### Intersection class
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Represents intersection(hit) information.
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### Transform
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Transformation is done in the following procedure.
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`M' = parent_xform x local_xform x local_pivot`
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## Memory management
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`Scene` and `Node` does not create a copy of asset data(e.g. vertices, indices). Thus user must care about memory management of scene assets in user side.
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## API
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API is still subject to change.
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### Node
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```cpp
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void Node::SetName(const std::string &name);
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```
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Set (unique) name for the node.
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```cpp
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void Node::AddChild(const type &child);
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```
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Add node as child node.
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```cpp
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void Node::SetLocalXform(const T xform[4][4]) {
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```
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Set local transformation matrix. Default is identity matrix.
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### Scene
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```cpp
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bool Scene::AddNode(const Node<T, M> &node);
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```
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Add a node to the scene.
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```cpp
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bool Scene::Commit() {
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```
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Commit the scene. After adding nodes to the scene or changed transformation matrix, call this `Commit` before tracing rays.
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`Commit` triggers BVH build in each nodes and updates node's transformation matrix.
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```cpp
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template<class H>
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bool Scene::Traverse(nanort::Ray<T> &ray, H *isect, const bool cull_back_face = false) const;
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```
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Trace ray into the scene and find an intersection.
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Returns `true` when there is an intersection and hit information is stored in `isect`.
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## TODO
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* [ ] Compute pivot point of each node(mesh).
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## Third party libraries and its icenses
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* picojson : BSD license.
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* bt3gui : zlib license.
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* glew : BSD/MIT license.
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* tinyobjloader : MIT license.
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* glm : The Happy Bunny License (Modified MIT License). Copyright (c) 2005 - 2017 G-Truc Creation
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* ImGui : The MIT License (MIT). Copyright (c) 2014-2015 Omar Cornut and ImGui contributors
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* ImGuizmo : The MIT License (MIT). Copyright (c) 2016 Cedric Guillemet
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