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| author | Michael R Sweet <michael.r.sweet@gmail.com> | 1999-01-13 19:28:54 +0000 |
|---|---|---|
| committer | Michael R Sweet <michael.r.sweet@gmail.com> | 1999-01-13 19:28:54 +0000 |
| commit | d7b88a3bcc7e76f38ee5799be7722fd5a10781ef (patch) | |
| tree | d8984d45424c9b2cdb199c1918f38bfea4a8211d /documentation/opengl.html | |
| parent | 30fa233681467b82b165e7d42cd0bea778b93768 (diff) | |
Updated all links so they work between files.
Revision 1.
git-svn-id: file:///fltk/svn/fltk/trunk@219 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
Diffstat (limited to 'documentation/opengl.html')
| -rw-r--r-- | documentation/opengl.html | 436 |
1 files changed, 189 insertions, 247 deletions
diff --git a/documentation/opengl.html b/documentation/opengl.html index f566d30ad..d618815d1 100644 --- a/documentation/opengl.html +++ b/documentation/opengl.html @@ -1,48 +1,33 @@ -<HTML> -<BODY> - -<H1 ALIGN=RIGHT><A NAME="opengl">9 - Using OpenGL</A></H1> - -This chapter discusses using FLTK for your OpenGL applications. - -<h2>Using OpenGL in FLTK</h2> - -The easiest way to make an OpenGL display is to subclass <a -href="#Fl_Gl_Window"><tt>Fl_Gl_Window</tt></a>. Your subclass must -implement a <tt>draw()</tt> method which uses OpenGL calls to draw the -display. Your main program should call <tt>redraw()</tt> when the -display needs to change, and (somewhat later) FLTK will call -<tt>draw()</tt>. - -<p>With a bit of care you can also use OpenGL to draw into normal FLTK -windows. This is mostly useful because you can use Gourand shading for -drawing your widgets. To do this you use the <a -href="#gl_start"><tt>gl_start()</tt></a> and <a -href="#gl_finish"><tt>gl_finish()</tt></a> functions around your OpenGL -code. - -<p>You must include FLTK's <tt><FL/gl.h></tt> header file. It will include -the file <tt><GL/gl.h></tt>, define some extra drawing functions -provided by FLTK, and include the <tt><windows.h></tt> header file needed -by WIN32 applications. - -<h2>Making a Subclass of Fl_Gl_Window</h2> - -To make a subclass of Fl_Gl_Window, you must provide: - -<ul> - - <li>A class definition. - <li>A <tt>draw()</tt> method. - <li>A <tt>handle()</tt> method (if you need to recieve input from - the user). -</ul> - -<h3>Defining the Subclass</h3> - -To define the subclass you just subclass <tt>Fl_Gl_Window</tt> class: - -<ul><pre> +<HTML><BODY> +<H1 ALIGN=RIGHT><A NAME=opengl>9 - Using OpenGL</A></H1> + This chapter discusses using FLTK for your OpenGL applications. +<H2>Using OpenGL in FLTK</H2> + The easiest way to make an OpenGL display is to subclass <A href=Fl_Gl_Window.html#Fl_Gl_Window> +<TT>Fl_Gl_Window</TT></A>. Your subclass must implement a <TT>draw()</TT> + method which uses OpenGL calls to draw the display. Your main program +should call <TT>redraw()</TT> when the display needs to change, and +(somewhat later) FLTK will call <TT>draw()</TT>. +<P>With a bit of care you can also use OpenGL to draw into normal FLTK +windows. This is mostly useful because you can use Gourand shading for +drawing your widgets. To do this you use the <A href=#gl_start><TT> +gl_start()</TT></A> and <A href=#gl_finish><TT>gl_finish()</TT></A> + functions around your OpenGL code. </P> +<P>You must include FLTK's <TT><FL/gl.h></TT> header file. It will +include the file <TT><GL/gl.h></TT>, define some extra drawing +functions provided by FLTK, and include the <TT><windows.h></TT> header +file needed by WIN32 applications. </P> +<H2>Making a Subclass of Fl_Gl_Window</H2> + To make a subclass of Fl_Gl_Window, you must provide: +<UL> +<LI>A class definition. </LI> +<LI>A <TT>draw()</TT> method. </LI> +<LI>A <TT>handle()</TT> method (if you need to recieve input from the +user). </LI> +</UL> +<H3>Defining the Subclass</H3> + To define the subclass you just subclass <TT>Fl_Gl_Window</TT> class: +<UL> +<PRE> class MyWindow : public Fl_Gl_Window { void draw(); int handle(int); @@ -51,17 +36,16 @@ public: MyWindow(int X, int Y, int W, int H, const char *L) : Fl_Gl_Window(X, Y, W, H, L) {} }; -</pre></ul> - -The <tt>draw()</tt> and <tt>handle()</tt> methods are described below. Like -any widget, you can include additional private and public data in your class -(such as scene graph information, etc.) - -<h3>The draw() Method</H3> - -The <tt>draw()</tt> method is where you actually do your OpenGL drawing: - -<ul><pre> +</PRE> +</UL> + The <TT>draw()</TT> and <TT>handle()</TT> methods are described below. + Like any widget, you can include additional private and public data in +your class (such as scene graph information, etc.) +<H3>The draw() Method</H3> + The <TT>draw()</TT> method is where you actually do your OpenGL +drawing: +<UL> +<PRE> void MyWindow::draw() { if (!valid()) { ... set up projection, viewport, etc ... @@ -70,14 +54,13 @@ void MyWindow::draw() { } ... draw ... } -</pre></ul> - -<h3>The handle() Method</h3> - -The <tt>handle()</tt> method handles mouse and keyboard events for the -window: - -<ul><pre> +</PRE> +</UL> +<H3>The handle() Method</H3> + The <TT>handle()</TT> method handles mouse and keyboard events for the +window: +<UL> +<PRE> int MyWindow::handle(int event) { switch(event) { case FL_PUSH: @@ -103,16 +86,16 @@ int MyWindow::handle(int event) { return 0; } } -</pre></ul> - -When <tt>handle()</tt> is called, the OpenGL context is not set up! If your -display changes, you should call <tt>redraw()</tt> and let <tt>draw()</tt> do the work. -Don't call any OpenGL drawing functions from inside <tt>handle()</tt>! - -<p>You can call some OpenGL stuff like hit detection and texture loading -functions by doing: - -<ul><pre> +</PRE> +</UL> + When <TT>handle()</TT> is called, the OpenGL context is not set up! + If your display changes, you should call <TT>redraw()</TT> and let <TT> +draw()</TT> do the work. Don't call any OpenGL drawing functions from +inside <TT>handle()</TT>! +<P>You can call some OpenGL stuff like hit detection and texture +loading functions by doing: </P> +<UL> +<PRE> case FL_PUSH: make_current(); // make OpenGL context current if (!valid()) { @@ -121,154 +104,116 @@ functions by doing: } ... ok to call NON-DRAWING OpenGL code here, such as hit detection, loading textures, etc... -</pre></ul> - -Your main program can now create one of your windows by doing <tt>new -MyWindow(...)</tt>. You can also use <a href="#fluid">fluid</a> by: - -<ol> - <li>Put your class definition in a MyWindow.H file. - - <li>In fluid create a box object, resize & place where you want. - - <li>In the control panel, fill in the "class" field with MyWindow.H. - This will make fluid produce constructors for your new class. - - <li>In the "extra code" put <tt>#include "MyWindow.H"</tt>, so - that the fluid output file will compile. - -</ol> - -You must put <tt>glwindow->show()</tt> in your main code after calling -<tt>show()</tt> on the window containing the OpenGL window. - -<h2>Using OpenGL in Normal FLTK Windows</h2> - -You can put OpenGL code into an <a -href="#draw"><tt>Fl_Widget::draw()</tt></a> method or into the code for -a <a href="#boxtypes">boxtype</a> or other places with some care. - -<p>Most important, before you show <i>any</i> windows (including those -that don't have OpenGL drawing) you must initialize FLTK so that it -knows it is going to use OpenGL. You may use any of the symbols -described for <a -href="#Fl_Gl_Window.mode"><tt>Fl_Gl_Window::mode()</tt></a> to describe -how you intend to use OpenGL: - -<ul><pre> +</PRE> +</UL> + Your main program can now create one of your windows by doing <TT>new +MyWindow(...)</TT>. You can also use <A href=fluid.html#fluid>fluid</A> + by: +<OL> +<LI>Put your class definition in a MyWindow.H file. </LI> +<LI>In fluid create a box object, resize place where you want. </LI> +<LI>In the control panel, fill in the "class" field with MyWindow.H. + This will make fluid produce constructors for your new class. </LI> +<LI>In the "extra code" put <TT>#include "MyWindow.H"</TT>, so that +the fluid output file will compile. </LI> +</OL> + You must put <TT>glwindow->show()</TT> in your main code after calling <TT> +show()</TT> on the window containing the OpenGL window. +<H2>Using OpenGL in Normal FLTK Windows</H2> + You can put OpenGL code into an <A href=#draw><TT>Fl_Widget::draw()</TT> +</A> method or into the code for a <A href=common.html#boxtypes>boxtype</A> + or other places with some care. +<P>Most important, before you show <I>any</I> windows (including those +that don't have OpenGL drawing) you must initialize FLTK so that it +knows it is going to use OpenGL. You may use any of the symbols +described for <A href=Fl_Gl_Window.html#Fl_Gl_Window.mode><TT> +Fl_Gl_Window::mode()</TT></A> to describe how you intend to use OpenGL: </P> +<UL> +<PRE> Fl::gl_visual(FL_RGB); -</pre></ul> - -You can then put OpenGL drawing code anywhere you can draw normally -by surrounding it with: - -<ul><pre> +</PRE> +</UL> + You can then put OpenGL drawing code anywhere you can draw normally by +surrounding it with: +<UL> +<PRE> gl_start(); ... put your OpenGL code here ... gl_finish(); -</pre></ul> - -<a name="gl_start"><tt>gl_start()</tt></a> and <a -name="gl_finish"><tt>gl_finish()</tt></a> set up an OpenGL context with -an orthographic projection so that 0,0 is the lower-left corner of the -window and each pixel is one unit. The current clipping is reproduced -with OpenGL <tt>glScissor()</tt> commands. These also synchronize the -OpenGL graphics stream with the drawing done by other X, WIN32, or FLTK -functions. - -<p>The same context is reused each time. If your code changes the -projection transformation or anything else you should use -<tt>glPushMatrix()</tt> and <tt>glPopMatrix()</tt> functions to put the -state back before calling <tt>gl_finish()</tt>. - -<p>You may want to use <tt>Fl_Window::current()->h()</tt> to get -the drawable height so you can flip the Y coordinates. - -<p>Unfortunately, there are a bunch of limitations you must adhere to for -maximum portability: - -<ul> - - <li>You must choose a default visual with <a - href="#gl_visual"><tt>Fl::gl_visual()</tt></a>. - - <li>You cannot pass <tt>FL_DOUBLE</tt> to <tt>Fl::gl_visual()</tt>. - - <li>You cannot use <tt>Fl_Double_Window</tt> or - <tt>Fl_Overlay_Window</tt>. - -</ul> - -Do <i>not</i> call <tt>gl_start()</tt> or <tt>gl_finish()</tt> when drawing -into an <tt>Fl_Gl_Window</tt>! - -<h2>OpenGL drawing functions</h2> - -FLTK provides some useful OpenGL drawing functions. They can be freely -mixed with any OpenGL calls, and are defined by including -<tt><FL/gl.H></tt> (which you should include instead of the OpenGL -header <tt><GL/gl.h></tt>). - -<h3>void gl_color(Fl_Color)</h3> - -Set the current color to a FLTK color index. <i>For color-index modes -it will use <tt>fl_xpixel(c)</tt>, which is only right if this window -uses the default colormap!</i> - -<h3>void gl_rect(int x, int y, int w, int h)<br> -void gl_rectf(int x, int y, int w, int h)</h3> - -Outline or fill a rectangle with the current color. If -<tt>ortho()</tt> has been called, then the rectangle will exactly fill -the pixel rectangle passed. - -<h3>void gl_font(Fl_Font fontid, int size)</h3> - -Set the "current OpenGL font" to the same font you get by calling -<a href="#fl_font"><tt>fl_font()</tt></a>. - -<h3>int gl_height()<br> -int gl_descent()<br> -float gl_width(const char *)<br> -float gl_width(const char *, int n)<br> -float gl_width(uchar)</h3> - -Return information about the current OpenGL font. - -<h3>void gl_draw(const char *)<br> -void gl_draw(const char *, int n)</h3> - -Draw a nul-terminated string or an array of <tt>n</tt> characters in -the current OpenGL font at the current <tt>glRasterPos</tt>. - -<h3>void gl_draw(const char *, int x, int y)<br> -void gl_draw(const char *, int n, int x, int y)<br> -void gl_draw(const char *, float x, float y)<br> -void gl_draw(const char *, int n, float x, float y)</h3> - -Draw a nul-terminated string or an array of <tt>n</tt> characters in -the current OpenGL font at the given position. - -<h3>void gl_draw(const char *, int x, int y, int w, int h, Fl_Align)</h3> - -Draw a string formatted into a box, with newlines and tabs expanded, -other control characters changed to ^X, and aligned with the edges or -center. Exactly the same output as <a href="#fl_draw"><tt>fl_draw()</tt></a>. - -<h2>Using OpenGL Optimizer with FLTK</h2> - -<a href="http://www.sgi.com/software/optimizer">OpenGL Optimizer</a> is -a scene graph toolkit for OpenGL available from Silicon Graphics for -IRIX and Microsoft Windows. Versions are in the works for Solaris and -HP-UX. It allows you to view large scenes without writing a lot of -OpenGL code. - -<h3>OptimizerWindow Class Definition</h3> - -To use OpenGL Optimizer with FLTK you'll need to create a subclass of -<tt>Fl_Gl_Widget</tt> that includes several state variables: - -<ul><pre> +</PRE> +</UL> +<A name=gl_start><TT>gl_start()</TT></A> and <A name=gl_finish><TT> +gl_finish()</TT></A> set up an OpenGL context with an orthographic +projection so that 0,0 is the lower-left corner of the window and each +pixel is one unit. The current clipping is reproduced with OpenGL <TT> +glScissor()</TT> commands. These also synchronize the OpenGL graphics +stream with the drawing done by other X, WIN32, or FLTK functions. +<P>The same context is reused each time. If your code changes the +projection transformation or anything else you should use <TT> +glPushMatrix()</TT> and <TT>glPopMatrix()</TT> functions to put the +state back before calling <TT>gl_finish()</TT>. </P> +<P>You may want to use <TT>Fl_Window::current()->h()</TT> to get the +drawable height so you can flip the Y coordinates. </P> +<P>Unfortunately, there are a bunch of limitations you must adhere to +for maximum portability: </P> +<UL> +<LI>You must choose a default visual with <A href=functions.html#gl_visual> +<TT>Fl::gl_visual()</TT></A>. </LI> +<LI>You cannot pass <TT>FL_DOUBLE</TT> to <TT>Fl::gl_visual()</TT>. </LI> +<LI>You cannot use <TT>Fl_Double_Window</TT> or <TT>Fl_Overlay_Window</TT> +. </LI> +</UL> + Do <I>not</I> call <TT>gl_start()</TT> or <TT>gl_finish()</TT> when +drawing into an <TT>Fl_Gl_Window</TT>! +<H2>OpenGL drawing functions</H2> + FLTK provides some useful OpenGL drawing functions. They can be +freely mixed with any OpenGL calls, and are defined by including <TT> +<FL/gl.H></TT> (which you should include instead of the OpenGL header <TT> +<GL/gl.h></TT>). +<H3>void gl_color(Fl_Color)</H3> + Set the current color to a FLTK color index. <I>For color-index modes +it will use <TT>fl_xpixel(c)</TT>, which is only right if this window +uses the default colormap!</I> +<H3>void gl_rect(int x, int y, int w, int h) +<BR> void gl_rectf(int x, int y, int w, int h)</H3> + Outline or fill a rectangle with the current color. If <TT>ortho()</TT> + has been called, then the rectangle will exactly fill the pixel +rectangle passed. +<H3>void gl_font(Fl_Font fontid, int size)</H3> + Set the "current OpenGL font" to the same font you get by calling <A href=drawing.html#fl_font> +<TT>fl_font()</TT></A>. +<H3>int gl_height() +<BR> int gl_descent() +<BR> float gl_width(const char *) +<BR> float gl_width(const char *, int n) +<BR> float gl_width(uchar)</H3> + Return information about the current OpenGL font. +<H3>void gl_draw(const char *) +<BR> void gl_draw(const char *, int n)</H3> + Draw a nul-terminated string or an array of <TT>n</TT> characters in +the current OpenGL font at the current <TT>glRasterPos</TT>. +<H3>void gl_draw(const char *, int x, int y) +<BR> void gl_draw(const char *, int n, int x, int y) +<BR> void gl_draw(const char *, float x, float y) +<BR> void gl_draw(const char *, int n, float x, float y)</H3> + Draw a nul-terminated string or an array of <TT>n</TT> characters in +the current OpenGL font at the given position. +<H3>void gl_draw(const char *, int x, int y, int w, int h, Fl_Align)</H3> + Draw a string formatted into a box, with newlines and tabs expanded, +other control characters changed to ^X, and aligned with the edges or +center. Exactly the same output as <A href=#fl_draw><TT>fl_draw()</TT></A> +. +<H2>Using OpenGL Optimizer with FLTK</H2> +<A href=http://www.sgi.com/software/optimizer>OpenGL Optimizer</A> is a +scene graph toolkit for OpenGL available from Silicon Graphics for IRIX +and Microsoft Windows. Versions are in the works for Solaris and +HP-UX. It allows you to view large scenes without writing a lot of +OpenGL code. +<H3>OptimizerWindow Class Definition</H3> + To use OpenGL Optimizer with FLTK you'll need to create a subclass of <TT> +Fl_Gl_Widget</TT> that includes several state variables: +<UL> +<PRE> class OptimizerWindow : public Fl_Gl_Window { csContext *context_; // Initialized to 0 and set by draw()... csDrawAction *draw_action_; // Draw action... @@ -291,33 +236,34 @@ public: void camera(csCamera *c) { camera_ = c; if (context_) { - draw_action_->setCamera(camera_); - camera_->draw(draw_action_); + draw_action_->setCamera(camera_); + camera_->draw(draw_action_); redraw(); } } }; -</ul><pre> +</PRE> +</UL> +<PRE> +</PRE> <H3>The camera() Method</H3> - -The <tt>camera()</tt> method sets the camera (projection and viewpoint) -to use when drawing the scene. The scene is redrawn after this call. - -<h3>The draw() Method</h3> - -The <tt>draw()</tt> method performs the needed initialization -and does the actual drawing: - -<ul><pre> + The <TT>camera()</TT> method sets the camera (projection and +viewpoint) to use when drawing the scene. The scene is redrawn after +this call. +<H3>The draw() Method</H3> + The <TT>draw()</TT> method performs the needed initialization and does +the actual drawing: +<UL> +<PRE> void OptimizerWindow::draw() { if (!context_) { // This is the first time we've been asked to draw; create the // Optimizer context for the scene... context_ = new csContext(fl_display, fl_visual); - context_->ref(); - context_->makeCurrent(fl_display, fl_window); + context_->ref(); + context_->makeCurrent(fl_display, fl_window); ... perform other context setup as desired ... @@ -325,19 +271,19 @@ void OptimizerWindow::draw() { draw_action_ = new csDrawAction; if (camera_) { - draw_action_->setCamera(camera_); - camera_->draw(draw_action_); + draw_action_->setCamera(camera_); + camera_->draw(draw_action_); } } if (!valid()) { // Update the viewport for this context... - context_->setViewport(0, 0, w(), h()); + context_->setViewport(0, 0, w(), h()); } // Clear the window... - context_->clear(csContext::COLOR_CLEAR | csContext::DEPTH_CLEAR, + context_->clear(csContext::COLOR_CLEAR | csContext::DEPTH_CLEAR, 0.0f, // Red 0.0f, // Green 0.0f, // Blue @@ -346,15 +292,11 @@ void OptimizerWindow::draw() { // Then draw the scene (if any)... if (scene_) - draw_action_->apply(scene_); + draw_action_->apply(scene_); } -</pre></ul> - +</PRE> +</UL> <H3>The scene() Method</H3> - -The <tt>scene()</tt> method sets the scene to be drawn. The scene is -a collection of 3D objects in a <tt>csGroup</tt>. The scene is redrawn -after this call. - -</BODY> -</HTML> + The <TT>scene()</TT> method sets the scene to be drawn. The scene is +a collection of 3D objects in a <TT>csGroup</TT>. The scene is redrawn +after this call. </BODY></HTML>
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