mimas::mesa_offscreen< T > Class Template Reference

Mesa off-screen rendering. More...

#include <mesa_offscreen.h>

Inheritance diagram for mimas::mesa_offscreen< T >:

[legend]Collaboration diagram for mimas::mesa_offscreen< T >:

[legend]List of all members.

Public Member Functions
	mesa_offscreen (x11_display *_display, image< T > &image, bool depthBuffer=false)
	Constructor.
virtual	~mesa_offscreen (void)
	Destructor.
virtual void	finish (void)
	Finish output on the image.
virtual void	ortho2D (int x1, int y1, int x2, int y2) const
	Switch to two-dimensional drawing mode.
virtual void	ortho2D (void) const
	Switch to two-dimensional drawing mode.
Protected Member Functions
GLenum	getFormat (void) const throw (mimasexception)
void	setupColorScale (void) const
Protected Attributes
Pixmap	pixmap
	X11 pixmap.
GLXPixmap	glxPixmap
	Corresponding GLX pixmap.
GLXContext	context
	GLX context for off-screen rendering.
void *	data
	Pointer to image-data to write back later.
int	width
	Width of image.
int	height
	Height of image.
bool	finishOffscreen

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Detailed Description

template<typename T>
class mimas::mesa_offscreen< T >

Mesa off-screen rendering.

Support for off-screen rendering using Mesa.

No stencil- and accumulation-buffer are allocated.

Do not forget to initialise glut at the beginning of your program:

    glutInit( &argc, argv );
    

The following example uses off-screen rendering to display text:

#include <GL/glut.h>
#include "mesa_offscreen.h"
#include "mesa_onscreen.h"
#include "image_mesaoutput.h"

using namespace boost;
using namespace std;
using namespace mimas;

image< rgba< unsigned char > > gaudy(void)
{
  image< rgba< unsigned char > > image; image.init( 256, 256 );
  for ( int k=0; k<=255; k++ )
    for ( int j=0; j<=255; j++ )
      image.pixel( k, j ) = rgba< unsigned char >( k, j, 255 - k );
  return image;
}

void rotatedText( mesa_base &m, int angle, const string &text ) {
  m.rectangle( 0, 0, 255, 255 );
  
  glPushMatrix();
  glTranslated( 20, 200, 0 );
  glScaled( 0.1, -0.1, 1.0 );
  glRotatef( angle, 0, 0, 1 );
  m.text( text );
  glPopMatrix();
}

int main( int argc, char *argv[] )
{
  int retVal = 0;

  // Initialise GLUT.
  glutInit( &argc, argv );

  try {

    // Open X11 display.
    x11_display display;

    // Off-screen rendering on colour- and grey-images.

    // Create two image-output windows.
    image_mesaoutput< rgba< unsigned char > > window( &display );

    // Create background images.
    image< rgba< unsigned char > > image( gaudy() );

    // Do some off-screen rendering on it.
    {
      mesa_offscreen< rgba< unsigned char > > m( &display, image, false );
      m.ortho2D();
      const rgba< unsigned char > green( 0, 128, 0 );
      m.setColor( green );
      rotatedText( m, 30, "offscreen" );
    };
      
    window << image << mimas::pause();

  } catch ( exception &e ) {

    cerr << e.what() << endl;
    retVal = 1;

  };
  
  return retVal;
}

If you experience problems, you may want to try:

    export LIBGL_ALWAYS_INDIRECT=1
    

This disables hardware rendering.

If it works:

• the problem is likely with the display driver
• it will be very slow

If it doesn't:

• there is a different bug, we need to fix

References:

• https://www.mesa3d.org/brianp/sig97/offscrn.htm

  Author:

  Jan Wedekind (jan at wedesoft.de)

  Date:

  Wed Mar 30 19:35:05 UTC 2005

Definition at line 58 of file mesa_offscreen.h.

---

Constructor & Destructor Documentation

template<typename T>

mimas::mesa_offscreen< T >::mesa_offscreen	(	x11_display *	_display,
		image< T > &	image,
		bool	depthBuffer = false
	)

Constructor.

Parameters:

	_display	X11 display
	image	Image to draw on.
	depthBuffer	Boolean indicating, wether to use a depth-buffer.

template<typename T>

virtual mimas::mesa_offscreen< T >::~mesa_offscreen

(

void

)

[virtual]

Destructor.

The destructor just calls the method finish() .

See also:

finish

---

Member Function Documentation

template<typename T>

virtual void mimas::mesa_offscreen< T >::finish

(

void

)

[virtual]

Finish output on the image.

This method

• calls glFinish()
• copies back the image-data, if HAVE_OSMESA is not defined.
• destructs all the resources related to off-screen rendering.
• finally calls mesa_base::finish .

  See also:

  mesa_base::finish

Reimplemented from mimas::mesa_base.

template<typename T>

virtual void mimas::mesa_offscreen< T >::ortho2D	(	int	x1,
		int	y1,
		int	x2,
		int	y2
	)			const [virtual]

Switch to two-dimensional drawing mode.

See also:

mesa_base::ortho2D

Implements mimas::mesa_base.

template<typename T>

virtual void mimas::mesa_offscreen< T >::ortho2D

(

void

)

const [virtual]

Switch to two-dimensional drawing mode.

See also:

mesa_base::ortho2D

Implements mimas::mesa_base.

template<typename T>

GLenum mimas::mesa_offscreen< T >::getFormat

(

void

)

const throw (mimasexception) [protected]

template<typename T>

void mimas::mesa_offscreen< T >::setupColorScale

(

void

)

const [protected]

---

Member Data Documentation

template<typename T>

Pixmap mimas::mesa_offscreen< T >::pixmap [protected]

X11 pixmap.

Definition at line 92 of file mesa_offscreen.h.

template<typename T>

GLXPixmap mimas::mesa_offscreen< T >::glxPixmap [protected]

Corresponding GLX pixmap.

Definition at line 94 of file mesa_offscreen.h.

template<typename T>

GLXContext mimas::mesa_offscreen< T >::context [protected]

GLX context for off-screen rendering.

Definition at line 96 of file mesa_offscreen.h.

template<typename T>

void* mimas::mesa_offscreen< T >::data [protected]

Pointer to image-data to write back later.

Definition at line 98 of file mesa_offscreen.h.

template<typename T>

int mimas::mesa_offscreen< T >::width [protected]

Width of image.

Definition at line 104 of file mesa_offscreen.h.

template<typename T>

int mimas::mesa_offscreen< T >::height [protected]

Height of image.

Definition at line 106 of file mesa_offscreen.h.

template<typename T>

bool mimas::mesa_offscreen< T >::finishOffscreen [protected]

Definition at line 108 of file mesa_offscreen.h.

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The documentation for this class was generated from the following file:

• mesa_offscreen.h

---