OGRE  13.4
Object-Oriented Graphics Rendering Engine
Setting up an OGRE project

Note
see Guide to building OGRE for instructions how to build OGRE itself

CMake Configuration

Ogre uses CMake as its build system. It is strongly recommended that you use it in your project as well. Then, all you need is to add the following lines to your project

# The COMPONENTS part checks that OGRE was built the way we need it
# The CONFIG flag makes sure we get OGRE instead of OGRE-next
find_package(OGRE REQUIRED COMPONENTS Bites CONFIG)
# add the source files as usual
add_executable(0_Bootstrap Bootstrap.cpp)
# this also sets the includes and pulls third party dependencies
target_link_libraries(0_Bootstrap OgreBites)

These settings already include any third party libraries the Components depends on (e.g. SDL) - nothing more to do. Alternatively use ${OGRE_LIBRARIES} to link against all available OGRE components.

Note
If you built OGRE statically, you also need find_package the used third-party libraries. e.g. find_package(ZLIB)

If you installed OGRE in a non-standard path, you will have to set OGRE_DIR to the location of OGREConfig.cmake so find_package can figure out the rest.

For inspecting the detected OGRE installation, the following CMake variables are available

  • OGRE_STATIC - whether ogre was build as static lib
  • OGRE_${COMPONENT}_FOUND - ${COMPONENT} is available
  • OGRE_PLUGIN_DIR - The directory where the OGRE plugins are located
  • OGRE_MEDIA_DIR - The directory where the OGRE sample media is located
  • OGRE_CONFIG_DIR - The directory where the OGRE config files are located

Application skeleton

The easiest way to get started is the OgreBites Component. It handles Ogre startup/ tear down (including Ogre::Overlay, RTSS), input using SDL2 and even includes a Simple GUI System.

This is useful if all you want is to get a Scene with a FPS counter up and running (rapid prototyping). If available it also uses SDL2 for input - you now just have to implement the callbacks.

To use it, simply derive from OgreBites::ApplicationContext and if you want to get input events from OgreBites::InputListener

{
...
}
Base class responsible for setting up a common context for applications.
Definition: OgreApplicationContextBase.h:87
the return values of the callbacks are ignored by ApplicationContext however they can be used to cont...
Definition: OgreInput.h:174

in the constructor we set our application name. The ogre configuration files will be stored in a system dependent location specific to our app.

MyTestApp::MyTestApp() : OgreBites::ApplicationContext("OgreTutorialApp")
{
}
ApplicationContextBase ApplicationContext
Definition: OgreApplicationContext.h:102
Definition: OgreAdvancedRenderControls.h:41

to handle input events, we then override the according method

bool MyTestApp::keyPressed(const OgreBites::KeyboardEvent& evt)
{
{
getRoot()->queueEndRendering();
}
return true;
}
@ SDLK_ESCAPE
Definition: OgreInput.h:118
Definition: OgreInput.h:58
Keysym keysym
Definition: OgreInput.h:60
Keycode sym
Definition: OgreInput.h:54

the interesting part however is the setup method

Note
The code is explained in detail in the Tutorial Your First Scene
void MyTestApp::setup(void)
{
// do not forget to call the base first
// register for input events
addInputListener(this);
// get a pointer to the already created root
Ogre::Root* root = getRoot();
// register our scene with the RTSS
shadergen->addSceneManager(scnMgr);
// without light we would just get a black screen
Ogre::Light* light = scnMgr->createLight("MainLight");
lightNode->setPosition(0, 10, 15);
lightNode->attachObject(light);
// also need to tell where we are
camNode->setPosition(0, 0, 15);
// create the camera
Ogre::Camera* cam = scnMgr->createCamera("myCam");
cam->setNearClipDistance(5); // specific to this sample
cam->setAutoAspectRatio(true);
camNode->attachObject(cam);
// and tell it to render into the main window
getRenderWindow()->addViewport(cam);
// finally something to render
Ogre::Entity* ent = scnMgr->createEntity("Sinbad.mesh");
node->attachObject(ent);
}
A viewpoint from which the scene will be rendered.
Definition: OgreCamera.h:86
void setAutoAspectRatio(bool autoratio)
If set to true a viewport that owns this frustum will be able to recalculate the aspect ratio wheneve...
Defines an instance of a discrete, movable object based on a Mesh.
Definition: OgreEntity.h:80
void setNearClipDistance(Real nearDist)
Sets the position of the near clipping plane.
Representation of a dynamic light source in the scene.
Definition: OgreLight.h:95
void setPosition(const Vector3 &pos)
Sets the position of the node relative to it's parent.
@ TS_PARENT
Transform is relative to the space of the parent node.
Definition: OgreNode.h:67
Shader generator system main interface.
Definition: OgreShaderGenerator.h:62
void addSceneManager(SceneManager *sceneMgr)
Add a scene manager to the shader generator scene managers list.
static ShaderGenerator * getSingletonPtr()
Get the singleton instance.
The root class of the Ogre system.
Definition: OgreRoot.h:67
SceneManager * createSceneManager()
create a default scene manager
Definition: OgreRoot.h:372
Manages the organisation and rendering of a 'scene': a collection of objects and potentially world ge...
Definition: OgreSceneManager.h:238
virtual Camera * createCamera(const String &name)
Creates a camera to be managed by this scene manager.
SceneNode * getRootSceneNode(void)
Gets the SceneNode at the root of the scene hierarchy.
virtual Light * createLight(const String &name)
Creates a light for use in the scene.
Entity * createEntity(const String &entityName, const String &meshName, const String &groupName=ResourceGroupManager::AUTODETECT_RESOURCE_GROUP_NAME)
Create an Entity (instance of a discrete mesh).
Class representing a node in the scene graph.
Definition: OgreSceneNode.h:61
virtual void attachObject(MovableObject *obj)
Adds an instance of a scene object to this node.
void lookAt(const Vector3 &targetPoint, TransformSpace relativeTo, const Vector3 &localDirectionVector=Vector3::NEGATIVE_UNIT_Z)
Points the local -Z direction of this node at a point in space.
virtual SceneNode * createChildSceneNode(const Vector3 &translate=Vector3::ZERO, const Quaternion &rotate=Quaternion::IDENTITY)
Creates an unnamed new SceneNode as a child of this node.
virtual void setup()
Sets up the context after configuration.

finally we start everything as

int main(int argc, char *argv[])
{
MyTestApp app;
app.initApp();
app.getRoot()->startRendering();
app.closeApp();
return 0;
}
Note
You can find the full code of the above example at
  • Samples/Tutorials/Bootstrap.cpp for C++
  • Samples/Python/sample.py for Python
  • Samples/AndroidJNI/MainActivity.java for Java (Android)
  • Samples/Csharp/example.cs for C#

OgreBites itself is also a good starting point if you need more control over the Camera or the Window creation. For instance to render into an existing Qt Window.

See also
Ogre::FileSystemLayer::getConfigFilePath
Ogre::Root::renderOneFrame
Ogre::RenderSystem::_createRenderWindow
Ogre::RenderSystem::preExtraThreadsStarted

Running your App

Ogre is divided into two library groups: main libraries and plugins.

Main libraries
The main library group contains the OgreMain library itself (named OgreMain.dll or libOgreMain.so depending on your platform) and the component libraries that rely on it.
On Linux you will typically install these into /usr/local/ which is automatically searched by the linker, so nothing more to do. On Windows however, you will have to either add the sdk/bin folder to PATH or copy your executable into sdk/bin.
Plugins
The second group of shared libraries are the plugins. Ogre pushes a good portion of its functionality into plugins so that they may be turned on or off easily at runtime. The core plugins that are included with Ogre have names that start with "Plugin_" and "Codec_". You can also write your own plugins.
Ogre also uses plugins for the different render systems (such as OpenGL, DirectX, etc). These plugins start with "RenderSystem_".

On Windows, the library and configuration files for Ogre can be found in the bin folder of the SDK. On Unix they are split into share/OGRE for configuration files, lib/ for libraries and lib/OGRE for Plugins.

Configuration Files

Ogre uses several configuration files (*.cfg) in the INI format. They control things like which plugins are loaded and where your application will search for resource files. We will briefly introduce you to each of these files. You'll slowly read more about them as you progress through the tutorials as well.

These files are searched in a set of predefined locations as described here. Alternatively, you can set the OGRE_CONFIG_DIR environment variable for a custom configuration file location.

Attention
The above sample code must find plugins.cfg and resources.cfg to function properly.

plugins.cfg

This file tells Ogre which plugins to load. You modify this file when you want to load a different set of plugins. It is often most useful to simply "comment out" lines instead of removing them, because you never know when a stroke of inspiration will mean you want to reload some unused plugins. Here is some sample content:

# Plugin=RenderSystem_Direct3D9
# Plugin=RenderSystem_Direct3D11
Plugin=RenderSystem_GL

We have the DirectX systems commented out, and an active line for OpenGL. On a windows system, you may have this reversed. You can see why it might be helpful not to delete unused lines, because then you have to try and remember whether it was RenderSystem_OpenGL or RenderSystem_GL.

You can also decide where Ogre looks for plugins by changing the PluginFolder variable. You can use both absolute and relative paths. Relative paths are resolved relative to the location of plugins.cfg.

For example, if you have built Ogre from source on a linux machine, then you will need a line like this at the beginning of your file:

PluginFolder=/usr/local/lib/OGRE

By default, Ogre would have been looking in the same directory where the plugins.cfg is located, which is sufficient on Windows.

Additionally, you can use the OGRE_PLUGIN_DIR environment variable to override the value of PluginFolder.

Note
Ogre is aware whether your app is a bundle. Therefore a relative path like Contents/Frameworks/ will be correctly resolved inside the app bundle on OSX.

resources.cfg

This file contains a list of the directories Ogre will use to search for resources. Resources include scripts, meshes, textures, GUI layouts, and others. You can also use both absolute and relative paths in this file, but you still cannot use environment variables. Relative paths are resolved relative to the location of resources.cfg. Ogre will not search subdirectories, so you have to manually enter them. Here is an example:

[General]
FileSystem=../media
FileSystem=../media/materials/scripts
FileSystem=../media/materials/textures
FileSystem=../media/models

Here is an example of a relative path being used and the need to list subdirectories. Including the '../media' directory did not automatically include the '../media/models' directory. This is so that Ogre doesn't get greedy and waste time loading up unneeded resources.

ogre.cfg

This file is generated by the Render Settings dialog that appears when you run your application. Do not distribute this file with your application. This file will be specific to your own setup. This file will contain your choices for things like screen resolution (see Ogre::RenderSystem::setConfigOption). Do not modify this file directly. Change the settings with the dialog and it will be automatically updated.

Depending on the OS, Ogre will place this config file in the writable path described here.