195 lines
6.7 KiB
HTML
195 lines
6.7 KiB
HTML
<HTML>
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<H1 ALIGN=RIGHT><A NAME="glut">D - GLUT Compatibility</A></H1>
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This appendix describes the GLUT compatibility header file supplied with
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FLTK.
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<H2>Using the GLUT Compatibility Header File</H2>
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You should be able to compile existing GLUT source code by including
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<tt><FL/glut.H></tt> instead of <tt><GL/glut.h></tt>. This can
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be done by editing the source, by changing the <tt>-I</tt> switches to
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the compiler, or by providing a symbolic link from <tt>GL/glut.h</tt>
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to <tt>FL/glut.H</tt>.
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<p><i>All files calling GLUT procedures must be compiled with C++</i>. You may
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have to alter them slightly to get them to compile without warnings,
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and you may have to rename them to get make to use the C++ compiler.
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<p>You must link with the FLTK library. If you call any GLUT drawing
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functions that FLTK does not emulate
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(<tt>glutExtensionsSupported()</tt>, <tt>glutWire*()</tt>,
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<tt>glutSolid*()</tt>, and <tt>glutStroke*()</tt>), you will also have
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to link with the GLUT library (<i>after</i> the FLTK library!)
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<p>Most of <tt>FL/glut.H</tt> is inline functions. You should take a
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look at it (and maybe at <tt>test/glut.cxx</tt> in the FLTK source) if
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you are having trouble porting your GLUT program.
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<p>This has been tested with most of the demo programs that come with
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the GLUT 3.3 distribution.
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<h2>Known Problems</h2>
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The following functions and/or arguments to functions are missing,
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and you will have to replace them or comment them out for your code to
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compile:
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<ul>
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<li><tt>glutLayerGet(GLUT_LAYER_IN_USE)</tt>
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<li><tt>glutLayerGet(GLUT_HAS_OVERLAY)</tt>
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<li><tt>glutSetColor(), glutGetColor(), glutCopyColormap()</tt>
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<li><tt>glutInitDisplayMode(GLUT_STEREO)</tt>
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<li><tt>glutInitDisplayMode(GLUT_LUMINANCE)</tt>
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<li><tt>glutPushWindow()</tt>
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<li><tt>glutWarpPointer()</tt>
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<li>Spaceball, buttonbox, dials, tablet functions,
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<tt>glutDeviceGet()</tt>
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<li><tt>glutWindowStatusFunc()</tt>
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<li><tt>glutGet(GLUT_WINDOW_NUM_CHILDREN)</tt>
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<li><tt>glutGet(GLUT_SCREEN_WIDTH_MM)</tt>
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<li><tt>glutGet(GLUT_SCREEN_HEIGHT_MM)</tt>
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<li><tt>glutGet(GLUT_ELAPSED_TIME)</tt>
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<li><tt>glutVideoResize()</tt> missing.
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</ul>
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Most of the symbols/enumerations have different values than
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GLUT uses. This will break code that relies on the actual values.
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The only symbols guaranteed to have the same values are true/false
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pairs like <tt>GLUT_DOWN</tt> and <tt>GLUT_UP</tt>, mouse
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buttons <tt>GLUT_LEFT_BUTTON, GLUT_MIDDLE_BUTTON,
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GLUT_RIGHT_BUTTON</tt>, and <tt>GLUT_KEY_F1</tt> thru
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<tt>F12</tt>.
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<p>The strings passed as menu labels are not copied.
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<p><tt>glutPostRedisplay()</tt> does not work if called from
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inside a display function. You must use <tt>glutIdleFunc()</tt>
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if you want your display to update continuously.
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<p><tt>glutSwapBuffers()</tt> does not work from inside a display
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function. This is on purpose, because FLTK swaps the buffers for you.
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<p><tt>glutUseLayer()</tt> does not work well, and should only be
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used to initialize transformations inside a resize callback. You
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should redraw overlays by using <tt>glutOverlayDisplayFunc()</tt>.
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<p>Overlays are cleared before the overlay display function is called.
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<tt>glutLayerGet(GLUT_OVERLAY_DAMAGED)</tt> always returns true for
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compatibility with some GLUT overlay programs. You must rewrite your
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code so that <tt>gl_color()</tt> is used to choose colors in an
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overlay, or you will get random overlay colors.
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<p><tt>glutSetCursor(GLUT_CURSOR_FULL_CROSSHAIR)</tt> just
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results in a small crosshair.
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<p>The fonts used by <tt>glutBitmapCharacter() and
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glutBitmapWidth()</tt> may be different.
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<p><tt>glutInit(argc,argv)</tt> will consume different switches than GLUT
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does. It accepts the switches recognized by <a
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href="#args"><tt>Fl::args()</tt></a>, and will accept any
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abbreviation of these switches (such as "-di" for "-display").
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<h2>Mixing GLUT and FLTK Code</h2>
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You can make your GLUT window a child of a <tt>Fl_Window</tt> with the
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following scheme. The biggest trick is that GLUT insists on
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<tt>show()</tt>'ing the window at the point it is created, which means the
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<tt>Fl_Window</tt> parent window must already be shown.
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<ul>
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<li>Don't call <tt>glutInit()</tt>.
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<li>Create your <tt>Fl_Window</tt>, and any FLTK widgets.
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Leave a blank area in the window for your GLUT window.
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<li><tt>show()</tt> the <tt>Fl_Window</tt>. Perhaps call
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<tt>show(argc,argv)</tt>.
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<li>Call <tt>window->begin()</tt> so that the GLUT window will
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be automatically added to it.
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<li>Use <tt>glutInitWindowSize()</tt> and
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<tt>glutInitWindowPosition()</tt> to set the location in the
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parent window to put the GLUT window.
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<li>Put your GLUT code next. It probably does not need many changes.
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Call <tt>window->end()</tt> immediately after the <tt>glutCreateWindow()</tt>!
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<li>You can call either <tt>glutMainLoop()</tt>,
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<tt>Fl::run()</tt>, or loop calling <tt>Fl::wait()</tt> to run
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the program.
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</ul>
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<hr break>
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<h2><a name="Fl_Glut_Window">class Fl_Glut_Window</a></h2>
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<hr>
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<h3>Class Hierarchy</h3>
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<ul><pre>
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<a href="#Fl_Gl_Window">Fl_Gl_Window</a>
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+----<b>Fl_Glut_Window</b>
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</pre></ul>
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<h3>Include Files</h3>
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<ul><pre>
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#include <FL/glut.H>
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</pre></ul>
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<h3>Description</h3>
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Each GLUT window is an instance of this class. You may find it useful to
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manipulate instances directly rather than use GLUT window id's. These
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may be created without opening the display, and thus can fit better
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into FLTK's method of creating windows.
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<p>The current GLUT window is available in the global variable
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<tt>glut_window</tt>.
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<p><tt>new Fl_Glut_Window(...)</tt> is the same as
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<tt>glutCreateWindow()</tt> except it does not <tt>show()</tt> the window
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or make the window current.
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<p><tt>window->make_current()</tt> is the same as
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<tt>glutSetWindow(number)</tt>. If the window has not had
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<tt>show()</tt> called on it yet, some functions that assumme an OpenGL
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context will not work. If you do <tt>show()</tt> the window, call
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<tt>make_current()</tt> again to set the context.
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<p><tt>~Fl_Glut_Window()</tt> is the same as
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<tt>glutDestroyWindow()</tt>.
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<h3>Methods</h3>
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<ul>
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<li><a href="#Fl_Glut_Window.Fl_Glut_Window">Fl_Glut_Window</a>
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<li><a href="#Fl_Glut_Window.~Fl_Glut_Window">~Fl_Glut_Window</a>
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</ul>
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<h4><a name="Fl_Glut_Window.Fl_Glut_Window">Fl_Glut_Window::Fl_Glut_Window(int x, int y, int w, int h, const char *title = 0)<br>
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Fl_Glut_Window::Fl_Glut_Window(int w, int h, const char *title = 0)</a></h4>
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The first constructor takes 4 int arguments to create the window with
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a preset position and size. The second constructor with 2 arguments
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will create the window with a preset size, but the window manager
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will choose the position according to it's own whims.
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<h4><a name="Fl_Glut_Window.~Fl_Glut_Window">virtual Fl_Glut_Window::~Fl_Glut_Window()</a></h4>
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Destroys the GLUT window.
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</BODY>
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</HTML>
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