Instead of labeling each method that needs to have visibility
we can label entire classes, this reduces the amount of noise and
potential for mistakes when writing classes.
The template parameters on vtkm::rendering::View are unnecessary. All
three of the templated classes are polymorphic (with virtual functions).
Thus, you just have to specify them at the constructor. Removing the
template parameters makes the syntax a bit cleaner and removes some
unnecessary duplication in the executable.
Removing the template does mean we cannot optimize in the future.
However, I expect us to start using more virtual methods rather than
less, so I think this is a move in the right direction.
Move some of the management of the width, height, and buffers to the base
Canvas class. Also, when it makes sense, get the width and height from
the rendering system.
Also changed the color buffer to be a Vec so that you don't have to
manage array offsets by hand.
All of these changes snowballed from the observation that the glut
example did not properly enable the depth buffer.
Specifically, I am trying to compile the code on OSX. OSX uses OpenGL
libraries in a different directory than most other installs (including
X11) and does not generally support GLX. These changes remove the files
that support GLX in systems that do not support it.
I also added several header files to the CMake lists that were not there
but should have been.
