SDL.Net + Tao.openGL pauses on each call to Gl.glBegin()

SDL Development
1

I’m trying to use OpenGL in a .NET program, and everything’s fine except
that I get almost a one second pause when glBegin is called, whether it
be called directly or as part of a vertex list. I’ve been looking around
and can’t find a reason. Might anyone here have a clue?
I’m initializing openGL with:**********************
screen = Video.SetVideoModeWindowOpenGL(width, height, true);
Sdl.SDL_GL_SetAttribute(Sdl.SDL_HWSURFACE, 1);
Sdl.SDL_GL_SetAttribute(Sdl.SDL_GL_DOUBLEBUFFER, 1);
Gl.glShadeModel(Gl.GL_SMOOTH);
Gl.glClearColor(bgColorR, bgColorG, bgColorB, 0.0f);
Gl.glClearDepth(1.0);
Gl.glEnable(Gl.GL_DEPTH_TEST);
Gl.glDepthFunc(Gl.GL_LEQUAL);
Gl.glHint( Gl.GL_PERSPECTIVE_CORRECTION_HINT, Gl.GL_NICEST );
Gl.glViewport( 0, 0, width, height );
Gl.glMatrixMode( Gl.GL_PROJECTION );
Gl.glLoadIdentity();
Glu.gluOrtho2D(win_left_edge,win_right_edge,win_bottom_edge,win_top_edge);
Gl.glMatrixMode( Gl.GL_MODELVIEW );
Gl.glLoadIdentity();

and then I draw with this:

Gl.glClear(Gl.GL_COLOR_BUFFER_BIT | Gl.GL_DEPTH_BUFFER_BIT);
Gl.glLoadIdentity();
Gl.glTranslatef(0.0f,0.0f,0.0f);
Gl.glEnable(Gl.GL_TEXTURE_2D);
Gl.glBegin(Gl.GL_QUADS); // Draw A Quad
Gl.glTexCoord2d(0.0, 1.0);
Gl.glVertex2i(-(int)(currentImgWidth/2),-(int)(currentImgHeight/2));
// Bottom Left
Gl.glTexCoord2d(1.0, 1.0); Gl.glVertex2i(
(int)(currentImgWidth/2),-(int)(currentImgHeight/2)); // Bottom
Right
Gl.glTexCoord2d(1.0, 0.0); Gl.glVertex2i( (int)(currentImgWidth/2),
(int)(currentImgHeight/2)); // Top Right
Gl.glTexCoord2d(0.0, 0.0); Gl.glVertex2i(-(int)(currentImgWidth/2),
(int)(currentImgHeight/2)); // Top Left
Gl.glEnd(); // Done Drawing The Quad
Gl.glFlush();

Sdl.SDL_GL_SwapBuffers();

or in one section I use glCallList, but that acts exactly the same. The
only thing i could think of is that maybe I’m missing some attributes to
set via SDL_DL_SetAttribute or something.
Also, I know that there is another way to flip the buffers via the Video
class (I forget the call right now), is there any difference between
that and SDL_GL_Swap_Buffers? If someone can help. that would be great,
this is an emergency now!

2

screen = Video.SetVideoModeWindowOpenGL(width, height, true);
Sdl.SDL_GL_SetAttribute(Sdl.SDL_HWSURFACE, 1);
Sdl.SDL_GL_SetAttribute(Sdl.SDL_GL_DOUBLEBUFFER, 1);

SDL_GL_SetAttribute needs to be done before SetVideoMode, and
SDL_HWSURFACE isn’t a valid attribute here.

Gl.glBegin(Gl.GL_QUADS); // Draw A Quad

This line always lags for one second?

Gl.glFlush();
Sdl.SDL_GL_SwapBuffers();

Don’t call glFlush() before SwapBuffers…SwapBuffers implies a flush, I
think.

–ryan.

3

Timothy Caraballo wrote:

I’m trying to use OpenGL in a .NET program, and everything’s fine
except that I get almost a one second pause when glBegin is called,
whether it be called directly or as part of a vertex list. I’ve been
looking around and can’t find a reason. Might anyone here have a clue?
I’m initializing openGL with:

screen = Video.SetVideoModeWindowOpenGL(width, height, true);
Sdl.SDL_GL_SetAttribute(Sdl.SDL_HWSURFACE, 1);
Sdl.SDL_GL_SetAttribute(Sdl.SDL_GL_DOUBLEBUFFER, 1);
Gl.glShadeModel(Gl.GL_SMOOTH);
Gl.glClearColor(bgColorR, bgColorG, bgColorB, 0.0f);
Gl.glClearDepth(1.0);
Gl.glEnable(Gl.GL_DEPTH_TEST);
Gl.glDepthFunc(Gl.GL_LEQUAL);
Gl.glHint( Gl.GL_PERSPECTIVE_CORRECTION_HINT, Gl.GL_NICEST );
Gl.glViewport( 0, 0, width, height );
Gl.glMatrixMode( Gl.GL_PROJECTION );
Gl.glLoadIdentity();
Glu.gluOrtho2D(win_left_edge,win_right_edge,win_bottom_edge,win_top_edge);

Gl.glMatrixMode( Gl.GL_MODELVIEW );
Gl.glLoadIdentity();

and then I draw with this:

Gl.glClear(Gl.GL_COLOR_BUFFER_BIT | Gl.GL_DEPTH_BUFFER_BIT);
Gl.glLoadIdentity();
Gl.glTranslatef(0.0f,0.0f,0.0f);
Gl.glEnable(Gl.GL_TEXTURE_2D);
Gl.glBegin(Gl.GL_QUADS); // Draw A Quad
Gl.glTexCoord2d(0.0, 1.0);
Gl.glVertex2i(-(int)(currentImgWidth/2),-(int)(currentImgHeight/2));
// Bottom Left
Gl.glTexCoord2d(1.0, 1.0); Gl.glVertex2i(
(int)(currentImgWidth/2),-(int)(currentImgHeight/2)); // Bottom
Right
Gl.glTexCoord2d(1.0, 0.0); Gl.glVertex2i( (int)(currentImgWidth/2),
(int)(currentImgHeight/2)); // Top Right
Gl.glTexCoord2d(0.0, 0.0); Gl.glVertex2i(-(int)(currentImgWidth/2),
(int)(currentImgHeight/2)); // Top Left
Gl.glEnd(); // Done Drawing The Quad
Gl.glFlush();

Sdl.SDL_GL_SwapBuffers();

or in one section I use glCallList, but that acts exactly the same.
The only thing i could think of is that maybe I’m missing some
attributes to set via SDL_DL_SetAttribute or something.
Also, I know that there is another way to flip the buffers via the
Video class (I forget the call right now), is there any difference
between that and SDL_GL_Swap_Buffers? If someone can help. that would
be great, this is an emergency now!

SDL mailing list
SDL at libsdl.org
http://www.libsdl.org/mailman/listinfo/sdl

As far as I can tell, there arn’t many taoists out there, so we really
need to help each other when we can.
I can’t replicate the issue on my end – not in my own code, nor with
the code you presented here – but our .NET environments may differ.
Are you using Mono or the Microsoft framework? What version?
Can you provide a full code example that demonstrates the problem (not
just out-of-context code snippets)? You may be doing something odd
outside of the code you presented here.

4

You may want also to post this to the Tao mailing list. Please post some
more of the code to provide a better context for the problem.

tao-list at lists.ximian.com
http://www.mono-project.com/Tao

Dave-------------------

Message: 4
Date: Wed, 12 Oct 2005 18:22:20 -0400
From: Timothy Caraballo
Subject: [SDL] SDL.Net + Tao.openGL pauses on each call to
Gl.glBegin()
To: SDL at libsdl.org
Message-ID: <434D8C9C.2020605 at pixelpod.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I’m trying to use OpenGL in a .NET program, and everything’s fine except
that I get almost a one second pause when glBegin is called, whether it
be called directly or as part of a vertex list. I’ve been looking around
and can’t find a reason. Might anyone here have a clue?
I’m initializing openGL with:

screen = Video.SetVideoModeWindowOpenGL(width, height, true);
Sdl.SDL_GL_SetAttribute(Sdl.SDL_HWSURFACE, 1);
Sdl.SDL_GL_SetAttribute(Sdl.SDL_GL_DOUBLEBUFFER, 1);
Gl.glShadeModel(Gl.GL_SMOOTH);
Gl.glClearColor(bgColorR, bgColorG, bgColorB, 0.0f);
Gl.glClearDepth(1.0);
Gl.glEnable(Gl.GL_DEPTH_TEST);
Gl.glDepthFunc(Gl.GL_LEQUAL);
Gl.glHint( Gl.GL_PERSPECTIVE_CORRECTION_HINT, Gl.GL_NICEST );
Gl.glViewport( 0, 0, width, height );
Gl.glMatrixMode( Gl.GL_PROJECTION );
Gl.glLoadIdentity();

Glu.gluOrtho2D(win_left_edge,win_right_edge,win_bottom_edge,win_top_edge);

Gl.glMatrixMode( Gl.GL_MODELVIEW );
Gl.glLoadIdentity();

and then I draw with this:

Gl.glClear(Gl.GL_COLOR_BUFFER_BIT | Gl.GL_DEPTH_BUFFER_BIT);
Gl.glLoadIdentity();
Gl.glTranslatef(0.0f,0.0f,0.0f);
Gl.glEnable(Gl.GL_TEXTURE_2D);
Gl.glBegin(Gl.GL_QUADS); // Draw A Quad
Gl.glTexCoord2d(0.0, 1.0);
Gl.glVertex2i(-(int)(currentImgWidth/2),-(int)(currentImgHeight/2));
// Bottom Left
Gl.glTexCoord2d(1.0, 1.0); Gl.glVertex2i(
(int)(currentImgWidth/2),-(int)(currentImgHeight/2)); // Bottom
Right
Gl.glTexCoord2d(1.0, 0.0); Gl.glVertex2i( (int)(currentImgWidth/2),
(int)(currentImgHeight/2)); // Top Right
Gl.glTexCoord2d(0.0, 0.0); Gl.glVertex2i(-(int)(currentImgWidth/2),
(int)(currentImgHeight/2)); // Top Left
Gl.glEnd(); // Done Drawing The Quad
Gl.glFlush();

Sdl.SDL_GL_SwapBuffers();

or in one section I use glCallList, but that acts exactly the same. The
only thing i could think of is that maybe I’m missing some attributes to
set via SDL_DL_SetAttribute or something.
Also, I know that there is another way to flip the buffers via the Video
class (I forget the call right now), is there any difference between
that and SDL_GL_Swap_Buffers? If someone can help. that would be great,
this is an emergency now!