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Note: The Agar manual pages follow certain conventions, notably
concerning function return values. Please read
AG_Intro(3)
first.
SYNOPSIS
#include <agar/core.h>
#include <agar/gui.h>
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DESCRIPTION
The
AG_GLView widget provides a low-level OpenGL context.
In order to be useful, two important functions must be registered: The
scale function and the
draw function.
The
scale function should set a projection matrix.
For example, a minimal scale function could be a simple call to
glOrtho(3). The
glMatrixMode() and
glLoadIdentity() functions are used before the scale function is invoked.
The
draw function renders the scene to the display.
Before calling the
draw function,
AG_GLView calls
glViewport(3). It also sets the
GL_TEXTURE, GL_PROJECTION, GL_MODELVIEW matrices and saves the state of the clipping planes by calling
glPushAttrib(3) with
GL_TRANSFORM_BIT.
In OpenGL mode, the Agar GUI elements are rendered using GL primitives, so
it is the responsibility of the caller to save and restore all GL state
(except for the matrices and clipping plane states), in the
draw function.
Typically,
AG_GLView is used as a base class to implement more specific scene-rendering widgets.
For example, the
SG_View(3) and
SK_View(3) widgets of FreeSG (http://freesg.org/) are subclasses of
AG_GLView. |
INHERITANCE HIERARCHY
INITIALIZATION
AG_GLView * AG_GLViewNew (AG_Widget *parent, Uint flags)
void AG_GLViewSizeHint (AG_GLView *glv, int w, int h)
void AG_GLViewDrawFn (AG_GLView *glv, void (*fn)(AG_Event *), const char *args, ...)
void AG_GLViewOverlayFn (AG_GLView *glv, void (*fn)(AG_Event *), const char *args, ...)
void AG_GLViewScaleFn (AG_GLView *glv, void (*fn)(AG_Event *), const char *args, ...)
void AG_GLViewKeydownFn (AG_GLView *glv, void (*fn)(AG_Event *), const char *args, ...)
void AG_GLViewKeyupFn (AG_GLView *glv, void (*fn)(AG_Event *), const char *args, ...)
void AG_GLViewButtondownFn (AG_GLView *glv, void (*fn)(AG_Event *), const char *args, ...)
void AG_GLViewButtonupFn (AG_GLView *glv, void (*fn)(AG_Event *), const char *args, ...)
void AG_GLViewMotionFn (AG_GLView *glv, void (*fn)(AG_Event *), const char *args, ...)
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The
AG_GLViewNew() function allocates, initializes, and attaches a new
AG_GLView widget.
Acceptable
flags include:
| AG_GLVIEW_HFILL | Expand horizontally in parent (equivalent to invoking
AG_ExpandHoriz(3)). | | AG_GLVIEW_VFILL | Expand vertically in parent (equivalent to invoking
AG_ExpandVert(3)). | | AG_GLVIEW_EXPAND | Shorthand for
AG_GLVIEW_HFILL|AG_GLVIEW_VFILL. |
AG_GLViewSizeHint() suggests an initial widget size in pixels.
The
AG_GLViewDrawFn() registers a the rendering function (specified in
AG_Event(3) format).
Prior to invoking this function, the widget will set the
glViewport(3) to the widget area, save the current OpenGL matrices and load the
widget-specific matrices.
AG_GLViewOverlayFn() registers a function that will be invoked after rendering, after the
GUI matrices and viewport have been restored.
It is typically used to draw text or controls independently of the
AG_GLViews projection and viewing matrices.
AG_GLViewScaleFn() registers a function to invoke whenever the widget is resized.
AG_GLViewKeydownFn(), AG_GLViewKeyupFn(), AG_GLViewButtondownFn(), AG_GLViewButtonupFn() and
AG_GLViewMotionFn() register general event handler functions that will be forwarded
key-down, key-up, mouse-button-down, mouse-button-up and
mouse-motion events, respectively.
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BINDINGS
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The
AG_GLView widget does not provide any binding.
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EVENTS
The
AG_GLView widget reacts to the following events:
| widget-moved | Projection matrix is recomputed and the
scale operation is invoked.
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The
AG_GLView widget does not generate any event.
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STRUCTURE DATA
For the
AG_GLView object:
| float mProjection[16] | Projection matrix (4x4, column-major) to automatically load every time the
AG_GLView is drawn.
Defaults to identity.
| | float mModelview[16] | Modelview matrix (4x4, column-major) to automatically load every time the
AG_GLView is drawn.
Defaults to identity.
| | float mTexture[16] | Texture matrix (4x4, column-major) to automatically load every time the
AG_GLView is drawn.
Defaults to identity.
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EXAMPLES
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See the
glview demo in the Agar
demos directory.
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SEE ALSO
HISTORY
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The
AG_GLView widget first appeared in
Agar 1.2.
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