Classes
You can find the following classes/files in the SGCT namespace that are relevant to application developers. For detailed API descriptions, see also the Doxygen documentation here.
Basic features
These are the features that are useful for the majority of SGCT application developers.
sgct.h
This file is a composite header that includes a number of different includes that might be used by application developers. You can use this include to get started quickly with SGCT at the stage of the project when you don’t need to worry about compilation times.
Engine
This class is the core of SGCT. There is more description about this class in the How it works section of this site. For each application there has to be exactly one instance of this class at any point.
readconfig.h
This file contains the function to read an XML cluster configuration into a configuration option which can be used to initialize the Engine class.
SharedData
The SharedData class is a singleton that handles the network synchronization of state between the server and the clients. The server has to provide the state it wants as a std::vector<unsigned char> to transmit to the clients in the Encode callback and the clients have to read the values in the Decode callback.
actions.h / joystick.h / keys.h / modifiers.h / mouse.h
These files contain all the enumerations that are necessary to use the interaction-based (keyboard, mouse, and joysticks/gamepads) callbacks.
ogl_headers.h
This file includes everything that is necessary to use OpenGL in the application code. If your application doesn’t want the GLAD based OpenGL bindings that come with SGCT, you should not include this file but use your own bindings instead. There should not be any interference between the internal bindings and a second library.
ShaderManager / ShaderProgram
These two classes handle the compilation, linking, and support of OpenGL shaders. The ShaderManager has a addShaderProgram function to create a new ShaderProgram that contains a vertex and a fragment shader source code. The ShaderManager also manages the shader programs that it creates and will destroy them in the tear down phase of the application. If the application needs to dispose of a shader program ahead of time, it has a removeShaderProgram function for this functionality.
TextureManager
The TextureManager loads images from disk and provides these as OpenGL textures. The loadTexture function loads, creates, and uploads an OpenGL texture and returns the object id of that texture that can be used in all subsequent OpenGL calls. That id can later be used in a call to removeTexture to dispose of the texture. All textures that are contained in the TextureManager when the application terminates are automatically freed.
Error
The error class is used to notify the application when an unrecoverable error has occurred. These errors range from error when reading the XML configuration file, problems when initializing the network component, or problems with the windowing system. Each error contains a unique error code, with each error code described in more detail here.
Font, FontManager, freetype.h
These classes and files are used to load, manage, and render fonts. The FontManager has a method called addFont that can be used to load individual fonts whose name can be used to access them through the font function, which returns a pointer to a Font object used in the print function in the freetype.h file to actually render text using the specific font. The font used in the addFont method should be a name of a font that is installed in the systems global Font directory. The print function takes, among others, the Font object used to render the text, and the x and y coordinates in screen space where the text should be rendered.
Log
The Log class has static methods used to render debug messages, informational text, warning messages, or errors to the console and optionally to a logging file on disk. The static Debug, Warning, Info, and Error functions can be used by the application in the same way. The class also supports the registration of a custom log callback that will be called whenever such a log message is queued.
Advanced features
These are features that are not necessary for the beginning use, but instead expose some of the underlying functions that can be used by applications that require more control.
config.h
This file defines the cluster setup that is used to initialize SGCT. The basic behavior is to use the readconfig.h to read an XML file which will create such a configuration from the configuration file, but directly using this file makes it possible to programmatically create these configurations or manipulate one that was read from the XML configuration.
Image
The Image class can be used by applications to load image files from disk or write image files to disk. The class supports reading PNGs, JPEGs, and TGA file formats. This class is used internally by the TextureReader to load textures.
Network / NetworkManager
The NetworkManager can be used to create new Network connections that can be used by the application for applications-specific tasks. Please note that it is not necessary to manually create any of the network connections used in a clustered environment. SGCT will create and manage those connections automatically. The network connections created from the NetworkManager can be instead used for some application-specific uses.
OffscreenBuffer
The OffscreenBuffer class can be used as a render target for application-specific rendering code. If the application, for example, requires a post processing step, it might be useful to render the application into an offscreen buffer first and then apply the post-processing before blitting the rendering into the SGCT provided buffer.
profiling.h
SGCT comes with a profiling library called Tracy, which is made available through this header file. Describing the steps needed to use Tracy would exceed this documentation, so you are referred to its documentation for more information on how to either compile the Tracy client or how to annotate your own application code to get more detailed profiling information.
Settings
These global settings can be queried and set by the application to programmatically influence the way SGCT operates. Please note that some of these settings need to be set before creating the Engine class as they are already used in that initial step of the pipeline. When in doubt, you are referred to the Doxygen documentation here.
Tracker, TrackingDevice, TrackingManager
These classes interface with the VRPN interface and make it possible to use external tracking information to steer client applications either by tracking a users position or provide a sensor user input through VRPN. See also the documentation for VRPN on how to use these features.
ClusterManager
This singleton class contains information about all the created Nodes and Users in the cluster. Its main use is the thisNode function which allows the client application to access settings of the node that it is running on. This can be used to, for example, query the local IP address, the number of Windows, or other settings. The ClusterManager contains Node instances for all nodes in the cluster, but all Nodes except that one that the specific application is running on are not fully initialized and should only be used in special situations.
As a clarification imaging that the application was loaded with a configuration that includes 3 nodes, 1 server and 2 clients. On all three nodes, the ClusterManager contains three Node instances, but only one of which is fully realized on each computer, the other two nodes representing the other computers are not fully initialized.
Node
The Node class represents the server node and all client nodes and is mainly a container for its IP address, the port at which the Node can be reached and a list of all Windows that are associated with the specific node. Only the current node that is running is fully initialized and has Windows to access.
Window
The Window class represents a single window that was created on the current node. The window is automatically created by the operating system, but most settings can be changed by the application afterwards. See the Doxygen documentation of the individual functions for more information. Additionally, each Window keep track of it Viewports that a window is subdivided in. The most common use case is that a Window has exactly one Viewport that is covering the entire window, but it is possible to tile a window with different viewports if such a behavior is desired.