266 lines
9.6 KiB
HTML
266 lines
9.6 KiB
HTML
<html>
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<body>
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<hr break>
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<h2><a name="Fl_Gl_Window">class Fl_Gl_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_Widget">Fl_Widget</a>
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+----<b>Fl_Gl_Window</b>
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+----<a href="#Fl_Pack">Fl_Pack</a>, <a href="#Fl_Scroll">Fl_Scroll</a>, <a href="#Fl_Tabs">Fl_Tabs</a>, <a href="#Fl_Tile">Fl_Tile</a>, <a href="#Fl_Window">Fl_Window</a>
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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/Fl_Gl_Window.H>
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</pre></ul>
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<h3>Description</h3>
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The <tt>Fl_Gl_Window</tt> widget sets things up so OpenGL works, and
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also keeps an OpenGL "context" for that window, so that changes to the
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lighting and projection may be reused between redraws.
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</tt>Fl_Gl_Window</tt> also flushes the OpenGL streams and swaps
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buffers after <tt>draw()</tt> returns.
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<p>OpenGL hardware typically provides some overlay bit planes, which
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are very useful for drawing UI controls atop your 3D graphics. If the
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overlay hardware is not provided, FLTK tries to simulate the overlay,
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This works pretty well if your graphics are double buffered, but not
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very well for single-buffered.
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<h3>Methods</h3>
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<center>
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<table width=90%>
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<tr>
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<td align=left valign=top>
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<ul>
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<li><a href="#Fl_Gl_Window.Fl_Gl_Window">Fl_Gl_Window</a>
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<li><a href="#Fl_Gl_Window.~Fl_Gl_Window">~Fl_Gl_Window</a>
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<li><a href="#Fl_Gl_Window.can_do">can_do</a>
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<li><a href="#Fl_Gl_Window.can_do_overlay">can_do_overlay</a>
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</ul>
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</td>
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<td align=left valign=top>
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<ul>
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<li><a href="#Fl_Gl_Window.draw">draw</a>
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<li><a href="#Fl_Gl_Window.draw_overlay">draw_overlay</a>
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<li><a href="#Fl_Gl_Window.handle">handle</a>
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</ul>
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</td>
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<td align=left valign=top>
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<ul>
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<li><a href="#Fl_Gl_Window.hide">hide</a>
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<li><a href="#Fl_Gl_Window.invalidate">invalidate</a>
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<li><a href="#Fl_Gl_Window.make_current">make_current</a>
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</ul>
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</td>
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<td align=left valign=top>
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<ul>
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<li><a href="#Fl_Gl_Window.make_overlay_current">make_overlay_current</a>
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<li><a href="#Fl_Gl_Window.mode">mode</a>
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<li><a href="#Fl_Gl_Window.ortho">ortho</a>
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</ul>
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</td>
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<td align=left valign=top>
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<ul>
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<li><a href="#Fl_Gl_Window.redraw_overlay">redraw_overlay</a>
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<li><a href="#Fl_Gl_Window.swap_buffers">swap_buffers</a>
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<li><a href="#Fl_Gl_Window.valid">valid</a>
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</ul>
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</td>
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</tr>
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</table>
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</center>
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<h4><a name="Fl_Gl_Window.Fl_Gl_Window">Fl_Gl_Window::Fl_Gl_Window(int x, int y, int w, int h, const char *label = 0)</a></h4>
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Creates a new <tt>Fl_Gl_Window</tt> widget using the given position, size, and
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label string. The default boxtype is <tt>FL_NO_BOX</tt>. The default mode is
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<tt>FL_RGB|FL_DOUBLE|FL_DEPTH</tt>.
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<h4><a name="Fl_Gl_Window.~Fl_Gl_Window">virtual Fl_Gl_Window::~Fl_Gl_Window()</a></h4>
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The destructor removes the widget and destroys the OpenGL context associated
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with it.
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<h4><a name="Fl_Gl_Window.draw">virtual void Fl_Gl_Window::draw(void)</a></h4>
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<tt>Fl_Gl_Window::draw()</tt> is a pure virtual method. You must
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subclass <tt>Fl_Gl_Window</tt> and provide an implementation for
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<tt>draw()</tt>. You may also provide an implementation of
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draw_overlay() if you want to draw into the overlay planes. You can
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avoid reinitializing the viewport and lights and other things by
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checking <tt>valid()</tt> at the start of <tt>draw()</tt> and only
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doing the initialization if it is false.
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<p>The <tt>draw()</tt> method can <i>only</i> use OpenGL calls. Do not
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attempt to call X, any of the functions in <FL/fl_draw.H>, or
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<tt>glX</tt> directly. Do not call <tt>gl_start()</tt> or
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<tt>gl_finish()</tt>.
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<p>If double-buffering is enabled in the window, the back and front buffers
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are swapped after this function is completed.
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<h4><a name="Fl_Gl_Window.mode">const int Fl_Gl_Window::mode() const<br>
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int Fl_Gl_Window::mode(int m)</a></h4>
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Set or change the OpenGL capabilites of the window. The value can be
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any of the following OR'd together:
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<ul>
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<li><tt>FL_RGB</tt> - RGB color (not indexed)
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<li><tt>FL_RGB8</tt> - RGB color with at least 8 bits of each color
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<li><tt>FL_INDEX</tt> - Indexed mode
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<li><tt>FL_SINGLE</tt> - not double buffered
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<li><tt>FL_DOUBLE</tt> - double buffered
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<li><tt>FL_ACCUM</tt> - accumulation buffer
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<li><tt>FL_ALPHA</tt> - alpha channel in color
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<li><tt>FL_DEPTH</tt> - depth buffer
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<li><tt>FL_STENCIL</tt> - stencil buffer
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<li><tt>FL_MULTISAMPLE</tt> - multisample antialiasing
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</ul>
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<tt>FL_RGB</tt> and <tt>FL_SINGLE</tt> have a value of zero, so they are
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"on" unless you give <tt>FL_INDEX</tt> or <tt>FL_DOUBLE</tt>.
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<p>If the desired combination cannot be done, FLTK will try turning off
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<tt>FL_MULTISAMPLE</tt>. If this also fails the <tt>show()</tt> will call
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<tt>Fl::error()</tt> and not show the window.
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<p>You can change the mode while the window is displayed. This
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is most useful for turning double-buffering on and off. Under
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X this will cause the old X window to be destroyed and a new one to be
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created. If this is a top-level window this will unfortunately also
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cause the window to blink, raise to the top, and be de-iconized, and
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the <tt>xid()</tt> will change, possibly breaking other code. It is best to
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make the GL window a child of another window if you wish to do this!
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<h4><a name="Fl_Gl_Window.can_do">static int Fl_Gl_Window::can_do(int)<br>
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int Fl_Gl_Window::can_do() const</a></h4>
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Returns non-zero if the hardware supports the given or current OpenGL mode.
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<h4><a name="Fl_Gl_Window.valid">char Fl_Gl_Window::valid() const<br>
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void Fl_Gl_Window::valid(char i)</a></h4>
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<tt>Fl_Gl_Window::valid()</tt> is turned off when FLTK creates a
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new context for this window or when the window resizes, and is turned
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on <i>after</i> <tt>draw()</tt> is called. You can use this inside your <tt>draw()</tt>
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method to avoid unneccessarily initializing the OpenGL context. Just
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do this:
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<ul><pre>
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void mywindow::draw() {
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if (!valid()) {
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glViewport(0,0,w(),h());
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glFrustum(...);
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glLight(...);
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...other initialization...
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}
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... draw your geometry here ...
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}
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<br>void Fl_Gl_Window::invalidate();
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<br>void Fl_Gl_Window::valid(char i);</a></h4>
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<tt>Fl_Gl_Window::valid()</tt> is turned off when FLTK creates a
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new context for this window and by the window resizing, and is turned
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on <i>after</i> draw() is called. You can use this inside your draw()
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method to avoid unneccessarily initializing the OpenGL context. Just
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do this:
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<pre><tt>void mywindow::draw() {
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if (!valid()) {
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glViewport(0,0,w(),h());
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glFrustum(...);
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glLight(...);
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...other initilization...
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}
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... draw your geometry here ...
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}
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</pre></ul>
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You can turn <tt>valid()</tt> on by calling <tt>valid(1)</tt>. You
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should only do this after fixing the transformation inside a
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<tt>draw()</tt> or after <tt>make_current()</tt>. This is done
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automatically after <tt>draw()</tt> returns.
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<h4><a name="Fl_Gl_Window.invalidate">void Fl_Gl_Window::invalidate()</a></h4>
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The <tt>invalidate()</tt> method turns off <tt>valid()</tt> and is
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equivalent to calling <tt>value(0)</tt>.
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<h4><a name="Fl_Gl_Window.ortho">void Fl_Gl_Window::ortho()</a></h4>
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Set the projection so 0,0 is in the lower left of the window and each
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pixel is 1 unit wide/tall. If you are drawing 2D images, your
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<tt>draw()</tt> method may want to call this if <tt>valid()</tt> is
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false.
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<h4><a name="Fl_Gl_Window.make_current">void Fl_Gl_Window::make_current()</a></h4>
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The <tt>make_current()</tt> method selects the OpenGL context for the
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widget. It is called automatically prior to the <tt>draw()</tt> method
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being called and can also be used to implement feedback and/or selection
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within the <tt>handle()</tt> method.
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<h4><a name="Fl_Gl_Window.make_overlay_current">void Fl_Gl_Window::make_overlay_current()</a></h4>
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The <tt>make_overlay_current()</tt> method selects the OpenGL context
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for the widget's overlay. It is called automatically prior to the
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<tt>draw_overlay()</tt> method being called and can also be used to
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implement feedback and/or selection within the <tt>handle()</tt>
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method.
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<h4><a name="Fl_Gl_Window.swap_buffers">void Fl_Gl_Window::swap_buffers()</a></h4>
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The <tt>swap_buffers()</tt> method swaps the back and front buffers.
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It is called automatically after the <tt>draw()</tt> method is called.
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<h4><a name="Fl_Gl_Window.hide">void Fl_Gl_Window::hide()</a></h4>
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Hides the window and destroys the OpenGL context.
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<h4><a name="Fl_Gl_Window.can_do_overlay">int Fl_Gl_Window::can_do_overlay()</a></h4>
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Returns true if the hardware overlay is possible. If this is false,
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FLTK will try to simulate the overlay, with significant loss of update
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speed. Calling this will cause FLTK to open the display.
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<h4><a name="Fl_Gl_Window.redraw_overlay">void Fl_Gl_Window::redraw_overlay()</a></h4>
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This method causes <tt>draw_overlay</tt> to be called at a later time.
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Initially the overlay is clear, if you want the window to display
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something in the overlay when it first appears, you must call this
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immediately after you <tt>show()</tt> your window.
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<h4><a name="Fl_Gl_Window.draw_overlay">virtual void Fl_Gl_Window::draw_overlay()</a></h4>
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You must implement this virtual function if you want to draw into the
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overlay. The overlay is cleared before this is called. You should
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draw anything that is not clear using OpenGL. You must use
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<tt>gl_color(i)</tt> to choose colors (it allocates them from the colormap
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using system-specific calls), and remember that you are in an indexed
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OpenGL mode and drawing anything other than flat-shaded will probably
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not work.
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<p>Both this function and <tt>Fl_Gl_Window::draw()</tt> should check
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<tt>Fl_Gl_Window::valid()</tt> and set the same transformation. If you
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don't your code may not work on other systems. Depending on the OS,
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and on whether overlays are real or simulated, the OpenGL context may
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be the same or different between the overlay and main window.
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</body>
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</html>
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