On 10/06/12 16:25, Mike Werner wrote:
>> On 10/05/12 16:03, Mike Werner wrote:
>>> I'm fairly sure FLTK is written with OpenGL.
>>
>> FLTK supports opengl, but does not use it for implementing widgets.
>> For that, FLTK uses the native graphics libraries:
>>
>> Linux: Xlib
>> Windows: Win32
>> OSX: Cocoa
>>
>> This allows FLTK apps that don't need openGL to run on machines
>> that don't have openGL.
>
> That's a surprise.
Yep -- the FLTK widgets are native drawing code.
OpenGL is simply supported as a feature, implementing opengl as a
special
rectangular area into which only opengl drawing can be done.
FLTK widgets can appear *around* an opengl drawing area, but not inside
it.
For instance, the FLTK 'cube' demo has two opengl areas inside a single
FLTK window; the fltk widgets are positioned /between/ the two opengl
areas.
The widgets can control operations that happen inside the opengl areas,
but FLTK widgets themselves can't be positioned /inside/ the opengl
rectangular regions, that I know of.
There is probably no reason FLTK couldn't provide widgets that are
opengl specific, but currently there are none that I know of that are
included with the distro. There might be third party extensions, though.
> I thought FLTK widgets were created using the OpenGL graphics library.
I just checked the FLTK docs introduction to make sure it is correct.
Quoting the first page of the "Introduction to FLTK" under 'Features':
http://fltk.org/doc-1.3/intro.html
"Written directly atop core libraries (Xlib, WIN32 or Cocoa) for maximum speed,
and carefully optimized for code size and performance."
..which is correct.
But perhaps elsewhere on that page, one of the mentions of openGL
might seem to indicate FLTK was /implemented/ with openGL, though
that's not the case.
For instance, perhaps this sentence on that same page under
"History of FLTK" is the one that confused you:
"The need to switch to OpenGL and GLX, portability, and a desire to use C++
subclassing required a rewrite of Forms. This produced the first version of
FLTK."
I could see reading that and thinking, 'oh, they wanted to switch to
opengl
to implement FLTK to make it more portable than Forms.', when that's
not actually the case.
Probably a small fix or two to the wording could clarify that, eg:
"The need to *support* OpenGL and GLX, offer portability across platforms,
and a desire to use C++ subclassing required a rewrite of Forms.
This produced the first version of FLTK..."
If there are other parts of the docs that gave the impression of FLTK
being implemented as opengl, let us know.
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