From d7b88a3bcc7e76f38ee5799be7722fd5a10781ef Mon Sep 17 00:00:00 2001 From: Michael R Sweet Date: Wed, 13 Jan 1999 19:28:54 +0000 Subject: Updated all links so they work between files. Revision 1. git-svn-id: file:///fltk/svn/fltk/trunk@219 ea41ed52-d2ee-0310-a9c1-e6b18d33e121 --- documentation/opengl.html | 436 ++++++++++++++++++++-------------------------- 1 file changed, 189 insertions(+), 247 deletions(-) (limited to 'documentation/opengl.html') 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 @@ - - - -

9 - Using OpenGL

- -This chapter discusses using FLTK for your OpenGL applications. - -

Using OpenGL in FLTK

- -The easiest way to make an OpenGL display is to subclass Fl_Gl_Window. Your subclass must -implement a draw() method which uses OpenGL calls to draw the -display. Your main program should call redraw() when the -display needs to change, and (somewhat later) FLTK will call -draw(). - -

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 gl_start() and gl_finish() functions around your OpenGL -code. - -

You must include FLTK's <FL/gl.h> header file. It will include -the file <GL/gl.h>, define some extra drawing functions -provided by FLTK, and include the <windows.h> header file needed -by WIN32 applications. - -

Making a Subclass of Fl_Gl_Window

- -To make a subclass of Fl_Gl_Window, you must provide: - -

A class definition. -
A draw() method. -
A handle() method (if you need to recieve input from - the user). -

- -

Defining the Subclass

- -To define the subclass you just subclass Fl_Gl_Window class: - -

+
+9 - Using OpenGL
+ This chapter discusses using FLTK for your OpenGL applications. 
+Using OpenGL in FLTK
+ The easiest way to make an OpenGL display is to subclass 
+Fl_Gl_Window. Your subclass must implement a draw()
+ method which uses OpenGL calls to draw the display.  Your main program 
+should call redraw() when the display needs to change, and 
+(somewhat later) FLTK will call draw(). 
+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 
+gl_start() and gl_finish()
+ functions around your OpenGL code. 
+You must include FLTK's <FL/gl.h> header file.  It will 
+include the file <GL/gl.h>, define some extra drawing 
+functions provided by FLTK, and include the <windows.h> header 
+file needed by WIN32 applications. 
+Making a Subclass of Fl_Gl_Window
+ To make a subclass of Fl_Gl_Window, you must provide: 
+
+A class definition. 
+A draw() method. 
+A handle() method (if you need to recieve input from  the 
+user). 
+
+Defining the Subclass
+ To define the subclass you just subclass Fl_Gl_Window class: 
+
+ 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) {}
 };
-
-
-The draw() and handle() methods are described below.  Like
-any widget, you can include additional private and public data in your class
-(such as scene graph information, etc.)
-
-The draw() Method
-
-The draw() method is where you actually do your OpenGL drawing:
-
-+
+
+ The draw() and handle() methods are described below. 
+ Like any widget, you can include additional private and public data in 
+your class (such as scene graph information, etc.) 
+The draw() Method
+ The draw() method is where you actually do your OpenGL 
+drawing: 
+
+ void MyWindow::draw() {
   if (!valid()) {
     ... set up projection, viewport, etc ...
@@ -70,14 +54,13 @@ void MyWindow::draw() {
   }
   ... draw ...
 }
-
-
-The handle() Method
-
-The handle() method handles mouse and keyboard events for the
-window:
-
-+
+
+The handle() Method
+ The handle() method handles mouse and keyboard events for the 
+window: 
+
+ int MyWindow::handle(int event) {
   switch(event) {
   case FL_PUSH:
@@ -103,16 +86,16 @@ int MyWindow::handle(int event) {
     return 0;
   }
 }
-
-
-When handle() is called, the OpenGL context is not set up!  If your
-display changes, you should call redraw() and let draw() do the work.
-Don't call any OpenGL drawing functions from inside handle()!
-
-You can call some OpenGL stuff like hit detection and texture loading
-functions by doing:
-
-
+
+
+ When handle() is called, the OpenGL context is not set up! 
+ If your display changes, you should call redraw() and let 
+draw() do the work. Don't call any OpenGL drawing functions from 
+inside handle()! 
+You can call some OpenGL stuff like hit detection and texture 
+loading functions by doing: 
+
+   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...
-
-
-Your main program can now create one of your windows by doing new
-MyWindow(...).  You can also use fluid by:
-
-
-	Put your class definition in a MyWindow.H file.
-
-	
In fluid create a box object, resize & place where you want.
-
-	
In the control panel, fill in the "class" field with MyWindow.H.
-	This will make fluid produce constructors for your new class.
-
-	
In the "extra code" put #include "MyWindow.H", so
-	that the fluid output file will compile.
-
-
-
-You must put glwindow->show() in your main code after calling
-show() on the window containing the OpenGL window.
-
-Using OpenGL in Normal FLTK Windows
-
-You can put OpenGL code into an Fl_Widget::draw() method or into the code for
-a boxtype or other places with some care.
-
-Most important, before you show any 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 Fl_Gl_Window::mode() to describe
-how you intend to use OpenGL:
-
-
+
+
+ Your main program can now create one of your windows by doing new 
+MyWindow(...).  You can also use fluid
+ by: 
+
+Put your class definition in a MyWindow.H file. 
+In fluid create a box object, resize place where you want. 
+In the control panel, fill in the "class" field with MyWindow.H. 
+ This will make fluid produce constructors for your new class. 
+In the "extra code" put #include "MyWindow.H", so  that 
+the fluid output file will compile. 
+
+ You must put glwindow->show() in your main code after calling 
+show() on the window containing the OpenGL window. 
+Using OpenGL in Normal FLTK Windows
+ You can put OpenGL code into an Fl_Widget::draw()
+ method or into the code for a boxtype
+ or other places with some care. 
+Most important, before you show any 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 
+Fl_Gl_Window::mode() to describe how you intend to use OpenGL: 
+
+ Fl::gl_visual(FL_RGB);
-
-
-You can then put OpenGL drawing code anywhere you can draw normally
-by surrounding it with:
-
-+
+
+ You can then put OpenGL drawing code anywhere you can draw normally by 
+surrounding it with: 
+
+ gl_start();
 ... put your OpenGL code here ...
 gl_finish();
-
-
-gl_start() and gl_finish() 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 glScissor() commands.  These also synchronize the
-OpenGL graphics stream with the drawing done by other X, WIN32, or FLTK
-functions.
-
-The same context is reused each time.  If your code changes the
-projection transformation or anything else you should use
-glPushMatrix() and glPopMatrix() functions to put the
-state back before calling gl_finish().
-
-
You may want to use Fl_Window::current()->h() to get
-the drawable height so you can flip the Y coordinates.
-
-
Unfortunately, there are a bunch of limitations you must adhere to for
-maximum portability:
-
-

-
-	You must choose a default visual with Fl::gl_visual().
-
-	
You cannot pass FL_DOUBLE to Fl::gl_visual().
-
-	
You cannot use Fl_Double_Window or
-	Fl_Overlay_Window.
-
-
-
-Do not call gl_start() or gl_finish() when drawing
-into an Fl_Gl_Window!
-
-OpenGL drawing functions
-
-FLTK provides some useful OpenGL drawing functions.  They can be freely
-mixed with any OpenGL calls, and are defined by including
-<FL/gl.H> (which you should include instead of the OpenGL
-header <GL/gl.h>).
-
-void gl_color(Fl_Color)
-
-Set the current color to a FLTK color index.  For color-index modes
-it will use fl_xpixel(c), which is only right if this window
-uses the default colormap!
-
-void gl_rect(int x, int y, int w, int h)

-void gl_rectf(int x, int y, int w, int h)
-
-Outline or fill a rectangle with the current color.  If
-ortho() has been called, then the rectangle will exactly fill
-the pixel rectangle passed.
-
-void gl_font(Fl_Font fontid, int size)
-
-Set the "current OpenGL font" to the same font you get by calling
-fl_font().
-
-int gl_height()

-int gl_descent()

-float gl_width(const char *)

-float gl_width(const char *, int n)

-float gl_width(uchar)
-
-Return information about the current OpenGL font.
-
-void gl_draw(const char *)

-void gl_draw(const char *, int n)
-
-Draw a nul-terminated string or an array of n characters in
-the current OpenGL font at the current glRasterPos.
-
-void gl_draw(const char *, int x, int y)

-void gl_draw(const char *, int n, int x, int y)

-void gl_draw(const char *, float x, float y)

-void gl_draw(const char *, int n, float x, float y)
-
-Draw a nul-terminated string or an array of n characters in
-the current OpenGL font at the given position.
-
-void gl_draw(const char *, int x, int y, int w, int h, Fl_Align)
-
-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 fl_draw().
-
-Using OpenGL Optimizer with FLTK
-
-OpenGL Optimizer 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.
-
-OptimizerWindow Class Definition
-
-To use OpenGL Optimizer with FLTK you'll need to create a subclass of
-Fl_Gl_Widget that includes several state variables:
-
-+
+
+gl_start() and 
+gl_finish() 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 
+glScissor() commands.  These also synchronize the OpenGL graphics 
+stream with the drawing done by other X, WIN32, or FLTK functions. 
+The same context is reused each time.  If your code changes the 
+projection transformation or anything else you should use 
+glPushMatrix() and glPopMatrix() functions to put the 
+state back before calling gl_finish(). 
+You may want to use Fl_Window::current()->h() to get the 
+drawable height so you can flip the Y coordinates. 
+Unfortunately, there are a bunch of limitations you must adhere to 
+for maximum portability: 
+
+You must choose a default visual with 
+Fl::gl_visual(). 
+You cannot pass FL_DOUBLE to Fl::gl_visual(). 
+You cannot use Fl_Double_Window or Fl_Overlay_Window
+. 
+
+ Do not call gl_start() or gl_finish() when 
+drawing into an Fl_Gl_Window! 
+OpenGL drawing functions
+ FLTK provides some useful OpenGL drawing functions.  They can be 
+freely mixed with any OpenGL calls, and are defined by including 
+<FL/gl.H> (which you should include instead of the OpenGL header 
+<GL/gl.h>). 
+void gl_color(Fl_Color)
+ Set the current color to a FLTK color index. For color-index modes 
+it will use fl_xpixel(c), which is only right if this window 
+uses the default colormap!
+void gl_rect(int x, int y, int w, int h)
+
 void gl_rectf(int x, int y, int w, int h)
+ Outline or fill a rectangle with the current color.  If ortho()
+ has been called, then the rectangle will exactly fill the pixel 
+rectangle passed. 
+void gl_font(Fl_Font fontid, int size)
+ Set the "current OpenGL font" to the same font you get by calling 
+fl_font(). 
+int gl_height()
+
 int gl_descent()
+
 float gl_width(const char *)
+
 float gl_width(const char *, int n)
+
 float gl_width(uchar)
+ Return information about the current OpenGL font. 
+void gl_draw(const char *)
+
 void gl_draw(const char *, int n)
+ Draw a nul-terminated string or an array of n characters in 
+the current OpenGL font at the current glRasterPos. 
+void gl_draw(const char *, int x, int y)
+
 void gl_draw(const char *, int n, int x, int y)
+
 void gl_draw(const char *, float x, float y)
+
 void gl_draw(const char *, int n, float x, float y)
+ Draw a nul-terminated string or an array of n characters in 
+the current OpenGL font at the given position. 
+void gl_draw(const char *, int x, int y, int w, int h, Fl_Align)
+ 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 fl_draw()
+. 
+Using OpenGL Optimizer with FLTK
+OpenGL Optimizer 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. 
+OptimizerWindow Class Definition
+ To use OpenGL Optimizer with FLTK you'll need to create a subclass of 
+Fl_Gl_Widget that includes several state variables: 
+
+ 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();
     }
   }
 };
-
+
+

The camera() Method

- -The camera() method sets the camera (projection and viewpoint) -to use when drawing the scene. The scene is redrawn after this call. - -

The draw() Method

- -The draw() method performs the needed initialization -and does the actual drawing: - -

+ The camera() method sets the camera (projection and 
+viewpoint) to use when drawing the scene. The scene is redrawn after 
+this call. 
+The draw() Method
+ The draw() method performs the needed initialization and does 
+the actual drawing: 
+
+ 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_);
 }
-
-
+

The scene() Method

- -The scene() method sets the scene to be drawn. The scene is -a collection of 3D objects in a csGroup. The scene is redrawn -after this call. - - - + The scene() method sets the scene to be drawn. The scene is +a collection of 3D objects in a csGroup. The scene is redrawn +after this call. \ No newline at end of file -- cgit v1.2.3

9 - Using OpenGL

Using OpenGL in FLTK

Making a Subclass of Fl_Gl_Window

Defining the Subclass

9 - Using OpenGL

Using OpenGL in FLTK

Making a Subclass of Fl_Gl_Window

Defining the Subclass

The draw() Method

The draw() Method

The handle() Method

The handle() Method

Using OpenGL in Normal FLTK Windows

Using OpenGL in Normal FLTK Windows

OpenGL drawing functions

void gl_color(Fl_Color)

void gl_rect(int x, int y, int w, int h)
-void gl_rectf(int x, int y, int w, int h)

void gl_font(Fl_Font fontid, int size)

int gl_height()
-int gl_descent()
-float gl_width(const char )
-float gl_width(const char , int n)
-float gl_width(uchar)

void gl_draw(const char )
-void gl_draw(const char , int n)

void gl_draw(const char , int x, int y)
-void gl_draw(const char , int n, int x, int y)
-void gl_draw(const char , float x, float y)
-void gl_draw(const char , int n, float x, float y)

void gl_draw(const char *, int x, int y, int w, int h, Fl_Align)

Using OpenGL Optimizer with FLTK

OptimizerWindow Class Definition

OpenGL drawing functions

void gl_color(Fl_Color)

void gl_rect(int x, int y, int w, int h) +
void gl_rectf(int x, int y, int w, int h)

void gl_font(Fl_Font fontid, int size)

int gl_height() +
int gl_descent() +
float gl_width(const char ) +
float gl_width(const char , int n) +
float gl_width(uchar)

void gl_draw(const char ) +
void gl_draw(const char , int n)

void gl_draw(const char , int x, int y) +
void gl_draw(const char , int n, int x, int y) +
void gl_draw(const char , float x, float y) +
void gl_draw(const char , int n, float x, float y)

void gl_draw(const char *, int x, int y, int w, int h, Fl_Align)

Using OpenGL Optimizer with FLTK

OptimizerWindow Class Definition

The camera() Method

The draw() Method

The draw() Method

The scene() Method

9 - Using OpenGL

Using OpenGL in FLTK

Making a Subclass of Fl_Gl_Window

Defining the Subclass

9 - Using OpenGL

Using OpenGL in FLTK

Making a Subclass of Fl_Gl_Window

Defining the Subclass

The draw() Method

The draw() Method

The handle() Method

The handle() Method

Using OpenGL in Normal FLTK Windows

Using OpenGL in Normal FLTK Windows

OpenGL drawing functions

void gl_color(Fl_Color)

void gl_rect(int x, int y, int w, int h) -void gl_rectf(int x, int y, int w, int h)

void gl_font(Fl_Font fontid, int size)

int gl_height() -int gl_descent() -float gl_width(const char *) -float gl_width(const char *, int n) -float gl_width(uchar)

void gl_draw(const char *) -void gl_draw(const char *, int n)

void gl_draw(const char *, int x, int y) -void gl_draw(const char *, int n, int x, int y) -void gl_draw(const char *, float x, float y) -void gl_draw(const char *, int n, float x, float y)

void gl_draw(const char *, int x, int y, int w, int h, Fl_Align)

Using OpenGL Optimizer with FLTK

OptimizerWindow Class Definition

OpenGL drawing functions

void gl_color(Fl_Color)

void gl_rect(int x, int y, int w, int h) + void gl_rectf(int x, int y, int w, int h)

void gl_font(Fl_Font fontid, int size)

int gl_height() + int gl_descent() + float gl_width(const char *) + float gl_width(const char *, int n) + float gl_width(uchar)

void gl_draw(const char *) + void gl_draw(const char *, int n)

void gl_draw(const char *, int x, int y) + void gl_draw(const char *, int n, int x, int y) + void gl_draw(const char *, float x, float y) + void gl_draw(const char *, int n, float x, float y)

void gl_draw(const char *, int x, int y, int w, int h, Fl_Align)

Using OpenGL Optimizer with FLTK

OptimizerWindow Class Definition

The camera() Method

The draw() Method

The draw() Method

The scene() Method

void gl_rect(int x, int y, int w, int h)
-void gl_rectf(int x, int y, int w, int h)

int gl_height()
-int gl_descent()
-float gl_width(const char )
-float gl_width(const char , int n)
-float gl_width(uchar)

void gl_draw(const char )
-void gl_draw(const char , int n)

void gl_draw(const char , int x, int y)
-void gl_draw(const char , int n, int x, int y)
-void gl_draw(const char , float x, float y)
-void gl_draw(const char , int n, float x, float y)

void gl_rect(int x, int y, int w, int h) +
void gl_rectf(int x, int y, int w, int h)

int gl_height() +
int gl_descent() +
float gl_width(const char ) +
float gl_width(const char , int n) +
float gl_width(uchar)

void gl_draw(const char ) +
void gl_draw(const char , int n)

void gl_draw(const char , int x, int y) +
void gl_draw(const char , int n, int x, int y) +
void gl_draw(const char , float x, float y) +
void gl_draw(const char , int n, float x, float y)