morph::Visual
#include <morph/Visual.h>
morph::Visual<> manages the graphical scene in which all your morphologica visualizations will exist.
You need at least one morph::Visual in your program. In general, one morph::Visual will relate to one window. If you have two or more Visuals, then you will have two or more windows.
This is the twowindows.cpp example program, which displays two windows with two morph::Visual instances.
Background: the morph::Visual GL version and OWNED_MODE
OpenGL Version
When you program with OpenGL, you have to choose which of the many versions of the library you want to use. This software uses ‘modern OpenGL’ which essentially means that we draw with GLSL shader programs. Modern OpenGL starts with OpenGL version 3.3, but version 4.1 was chosen as a starting point as this is supported across the Linux, Mac and Windows platforms.
OpenGL 4.1 was originally the only option, but more recently Visual and friends were extended to support other OpenGL versions, including OpenGL 4.1 to 4.6 (which makes it possible to use GL compute shaders) and OpenGL 3.0 ES and up, which makes it possible to run morphologica programs on the Raspberry Pi.
The OpenGL version is passed to morph::Visual as a single template argument glver of type int.
The default value for glver is morph::gl::version_4_1 which requests the core version 4.1 of OpenGL. The integer values that specify each OpenGL version are defined in morph/gl/version.h. Both the ‘desktop’ OpenGL versions (from 4.1 up to 4.6) and the ‘ES’ versions (3.0 ES to 3.2 ES) are supported in both core and compatibility modes.
The OpenGL version integer is also used as a template parameter in the morph::VisualModel objects that will populate your morph::Visual. You should ensure that the same value for the GL version is used across all classes.
OWNED_MODE
One more concept to introduce before getting into morph::Visual usage is the ‘operating mode’. When Visual was first developed, it was designed to own its desktop window, which would always be provided by the GLFW library. The Visual class would manage GLFW setup and window creation/destruction. Window pointers (aliased as morph::win_t) were simply of type GLFWwindow.
Later on, I wanted to add support for the Qt windowing system so that a morph::Visual could provide OpenGL graphics for a QtWidget. Qt manages OpenGL contexts and windows, so I had to create a new operating mode for morph::Visual in which it would use an externally managed context. To do this I defined OWNED_MODE. OWNED_MODE is enabled by #define OWNED_MODE 1 in a relevant location (see viswidget.h for Qt and viswx.h for wx windows).
In owned mode, an alternative windowing system can be used and morph::win_t is mapped to the appropriate window/widget type. Code that is involved in setting up the windowing system is disabled.
However, unless you are integrating morphologica into Qt or WxWidgets, you will leave OWNED_MODE undefined.