In the effects folder you can find a few useful Shader Effects that can be used directly with your own projects, or used as inspiration or for learning. Note that these Effects don't depend on the window manager.

All effects are composed of a simple class that inherits from the Effect Class, and contains one or more Shaders.

Some Examples (there are more in the folder, check them out!):

phongshader - a simple Phong Shader that receives a Mesh and two Trackballs, one for the camera and one for the light direction.
rendertexture - a simple shader that renders a given texture using a quad as proxy geometry.
gradientfilter - applies a Sobel filter on an image.
toon - classic toon shader effect.
ssao - Screen Space Ambient Occlusion - a more advanced effect that uses multiple render passes.

Using an Effect

The only necessary step is to include the .hpp file in your project, and make sure the directory containing the shaders are set corretly.

For example, lets look at the phongshader effect:

First include the file (make sure you have the include path set correctly so your compiler can find the file):

1 #include <phongshader.hpp>

Then create an instance of the phong effect, here we are creating as a pointer but it is not necessary.

 Phong* phong =  new Phong();
 phong->setShadersDir("../effects/shaders/");
 // make sure GLEW is initialized at this moment
 phong->initialize();

Note that it is not necessary to create your effect variable as a pointer, just make sure the initialize() method is called after GLEW is initialized.

Once the effect is initialized it can be used to render a mesh. The Phong Shader example works by passing a Mesh, a camera Trackball and a light Trackball. A simple application draw method would look like this:

 glClearColor(1.0, 1.0, 1.0, 0.0);
 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 phong->render(mesh, camera_trackball, light_trackball);
 camera_trackball.render(); // renders the trackball visual representation

The mesh is rendered using the camera_trackball for retrieving the viewport, view and projection matrices, and the light_trackball for the light direction. The model matrix is retrieved from the mesh.

Some effects have set methods for the parameters, their usage is straightforward.