License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Architecture

This scene graph library is based on OpenGL 3.2/GLSL 1.5 Core Profile and C++11. It is primarily intended for educational use in the lectures Computer Graphics and Interaction (MIN-CGI, M.Sc.) and Computergrafik 1 (BIN-CG1, B.Sc.) as well as the accompanying exercises at University of Applied Sciences and Arts Hannover.

Cf. lecture notes MIN-CGI, chapter 4 (Scene Graphs) or BIN-CG1, chapter 6 (Szenengraphen).

The central classes are scg::Viewer, scg::Renderer, scg::Traverser, scg::Node, and scg::Core as well as its sub-classes. The rendering is controlled by Viewer::startMainLoop() and performed by Renderer::render(), Node::render(), Core::render() as well as the render() methods of the appropriate sub-classes.

The Names of vertex attributes and uniform variables are defined in the class OGLConstants (file ) and in the GLSL structs Light and Material (file shaders/blinn_phong_lighting.glsl ). They can also be found as in attributes and uniform variables in the supplied shaders (folder shaders).

Directory structure

src: source code of scene graph base; all header files are included in scg3.h
src_ext: source code of scene graph extensions, e.g., for virtual reality applications; all header files are included in scg3_ext.h
extern: source code of external libraries GLEW, GLM, and stb_image
models: OBJ geometry models (scg3 has a very basic OBJ parser)
shaders: GLSL shader code
textures: JPEG, PNG, GIF, BMP texture images (plus a few other file formats supported by stb_image)

Models, shaders, and textures are provided for test applications. Real applications should use their own folders independent of the scg3 source directory.

Usage

Installation and Linking

Prerequisites: OpenGL 3.2 (or higher), GLFW 3.2.0 (or higher) C++ Compiler: GCC 4.6 (or higher), Clang 3.1 (or higher), Visual C++ 11.0 (Visual Studio 2012, or higher)

Build of library scg3: Project files for Eclipse (Linux, MacOS and Windows/MinGW), Visual Studio 2012 (Windows), and CMake files (Linux) are provided.

Build of application under Linux:

g++ -g -c -std=c++11 -I../scg3 my_prog.cpp
g++ -L../scg3/DebugLinux -o my_prog my_prog.o -lscg3 -lglfw3 -lGL -lX11 -lXxf86vm -lXrandr -lpthread -lXi -lrt -ldl -lXinerama -lXcursor

Build of application under macOS:

g++ -g -c -std=c++11 -I../scg3 my_prog.cpp
g++ -L../scg3/DebugMacOS -L/usr/local/lib -o my_prog my_prog.o -lscg3 -lglfw -framework OpenGL -framework Cocoa -framework IOKit -framework CoreVideo

Build of application under Windows/MinGW:

g++ -g -c -std=c++11 -I../scg3 my_prog.cpp
g++ -L../scg3/DebugWindows -o my_prog.exe my_prog.o -lscg3 -lglfw3 -lopengl32 -lgdi32

Example Application

Cf. lecture notes MIN-CGI, chapter 4 (Scene Graphs) or BIN-CG1, chapter 6 (Szenengraphen).

// scg3 minimal example application
#include <scg3.h>
using namespace scg;
int main() {
  // create viewer with default renderer, camera, and light
  auto viewer = Viewer::create();
  CameraSP camera;
  GroupSP scene;
  LightSP light;
  viewer->initSimpleRenderer(camera, scene, light);
  // define red material
  auto matRed = MaterialCore::create();
  matRed->setAmbientAndDiffuse(glm::vec4(1.f, 0.5f, 0.5f, 1.f))
        ->setSpecular(glm::vec4(1.f, 1.f, 1.f, 1.f))
        ->setShininess(20.f)
        ->init();
  // add teapot shape to scene graph
  GeometryCoreFactory geometryFactory;
  auto teapot = Shape::create();
  teapot->addCore(matRed)
        ->addCore(geometryFactory.createTeapot(1.f));
  light->addChild(teapot);
  // move camera backwards, enter main loop
  camera->translate(glm::vec3(0.f, 0.f, 1.f))
        ->dolly(-1.f);
  viewer->startMainLoop();
  return 0;
}

See also the more advanced example scg3_table_scene_example.cpp (folder doc) and the supplied shaders (folder shaders).

Acknowledgments

This scene graph implementation utilizes ideas and contributions of Prof. Dr. Henrik Tramberend, Prof. Dr. Frauke Sprengel, Jan Gericke, Bastian Hellmann, Benedikt Köhler, Alexander Schulz, and Marcus Wichelmann.

It is further influenced by the open-source scene graph libraries OpenSceneGraph and OpenSG.

http://www.openscenegraph.org/

http://www.opensg.org/

The open-source libraries GLEW 2.1.0, GLFW 3.2.0, GLM 0.9.9.3, and stb_image 2.21 are used. GLEW, GLM, and stb_image are included as source code in folder extern. GLFW 3.2.0 (or newer) has to be installed by the user (cf. http://www.glfw.org/).

http://glew.sourceforge.net/

http://www.glfw.org/

http://glm.g-truc.net/

https://github.com/nothings/stb

Release Notes

Version 0.6 (March 2019)

introduced in BIN-CG1 lecture of summer 2019
update to GLEW 2.1.0, GLFW 3.2, GLM 0.9.9.3, stb_image 2.21
replace glProgramUniform() by glUniform() to keep OpenGL 3.2 compatibility
fix bugs in MouseController
add CMake support for Linux
remove C++11 workarounds

Version 0.5 (March 2014)

rename vascg3 to scg3
add OS X build configurations, support Clang compiler

Version 0.4 (January 2014)

include GLEW 1.10.0 as source code
fix bug in Camera::getViewDirection()

Version 0.3 (October 2013):

introduced in CGI lecture of winter 2013/14
remove dependency on GLU
update to GLFW 3.0.2 and GLM 0.9.4.5
remove GLEW and GLFW from source code, link as external libraries instead
fix bug in ShaderCore::checkLinkError_()
fix exception handling
add Renderer::setGlobalAmbientLight(), Renderer::setLighting, and RenderState::setLighting()
add GeometryCoreFactory::createTeapotFlat()

Version 0.2 (February 2013):

introduced in ICG lecture of summer 2013
integrate CameraTransformation into Camera, making CameraTransformation obsolete
new, more intuitive and more exact camera control
support method chaining for nodes, cores, and viewer
new method Viewer::initSimpleRenderer() to reduce code for simple applications
several other minor improvements
update GLFW to 2.7.7
update GLM to 0.9.4.2
integrate GLEW 1.9.0 as source code

Version 0.1 (October 2012):

introduced in SVR lecture of winter 2012/13
scene graph extensions src_ext for stereo rendering
several modifications to existing classes required for stereo rendering
integrate GLFW as source code

Version 0.0 (March 2012):

introduced in ICG lecture of summer 2012
OpenGL 3 rewrite of library vascg2
integrate GLFW as source code