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graveyard filla

window trailing with just empty window or quad drawn...

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high, im following the nehe openGL tutorials. anyway, the first 2 tuturials (opening a window and drawing a tri/quad) are giving me a trailing effect on the window. im using the SDL / linux version of the code, but ive 'ported it' to windows. (using win xp and .net 2k3)... anyway, maybe this is why this is happening? im very new to openGL although i have experiance with SDL. this happends when i resize the window, or move it around off-screen (ie below the "Start" task bar).. it goes like this for a few seconds before it "snaps out of it".. heres what my code and the problem looks like, maybe theres something obvious im over-looking and someone can spot it out.. thanks for any help! (again its only the tutoral #2 SDL/linux version ported to windows)
/*
 * This code was created by Jeff Molofee '99 
 * (ported to Linux/SDL by Ti Leggett '01)
 *
 * If you've found this code useful, please let me know.
 *
 * Visit Jeff at http://nehe.gamedev.net/
 * 
 * or for port-specific comments, questions, bugreports etc. 
 * email to leggett@eecs.tulane.edu
 */
 
#ifdef _WIN32
#pragma comment(lib, "SDL.lib")
#pragma comment(lib, "SDLmain.lib")
#pragma comment(lib, "OpenGL32.lib")
#pragma comment(lib, "GlU32.lib")
#endif

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <SDL.h>

/* screen width, height, and bit depth */
#define SCREEN_WIDTH  640
#define SCREEN_HEIGHT 480
#define SCREEN_BPP     16

/* Define our booleans */
#define TRUE  1
#define FALSE 0

float zoom = 3.0f;
/* This is our SDL surface */
SDL_Surface *surface;

/* function to release/destroy our resources and restoring the old desktop */
void Quit( int returnCode )
{
    /* clean up the window */
    SDL_Quit( );

    /* and exit appropriately */
    exit( returnCode );
}

/* function to reset our viewport after a window resize */
int resizeWindow( int width, int height )
{
    /* Height / width ration */
    GLfloat ratio;

    /* Protect against a divide by zero */
    if ( height == 0 )
	height = 1;

    ratio = ( GLfloat )width / ( GLfloat )height;

    /* Setup our viewport. */
    glViewport( 0, 0, ( GLsizei )width, ( GLsizei )height );

    /* change to the projection matrix and set our viewing volume. */
    glMatrixMode( GL_PROJECTION );
    glLoadIdentity( );

    /* Set our perspective */
    gluPerspective( 45.0f, ratio, 0.1f, 100.0f );

    /* Make sure we're chaning the model view and not the projection */
    glMatrixMode( GL_MODELVIEW );

    /* Reset The View */
    glLoadIdentity( );

    return( TRUE );
}

/* function to handle key press events */
void handleKeyPress( SDL_keysym *keysym )
{
    switch ( keysym->sym )
	{
	case SDLK_ESCAPE:
	    /* ESC key was pressed */
	    Quit( 0 );
	    break;
	case SDLK_F1:
	    /* F1 key was pressed
	     * this toggles fullscreen mode
	     */
	    SDL_WM_ToggleFullScreen( surface );
	    break;
	default:
	    break;
	}

    return;
}

/* general OpenGL initialization function */
int initGL( GLvoid )
{

    /* Enable smooth shading */
    glShadeModel( GL_SMOOTH );

    /* Set the background black */
    glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );

    /* Depth buffer setup */
    glClearDepth( 1.0f );

    /* Enables Depth Testing */
    glEnable( GL_DEPTH_TEST );

    /* The Type Of Depth Test To Do */
    glDepthFunc( GL_LEQUAL );

    /* Really Nice Perspective Calculations */
    glHint( GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST );

    return( TRUE );
}

/* Here goes our drawing code */
int drawGLScene( GLvoid )
{
    /* These are to calculate our fps */
    static GLint T0     = 0;
    static GLint Frames = 0;

    /* Clear The Screen And The Depth Buffer */
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

    /* Move Left 1.5 Units And Into The Screen 6.0 */
    glLoadIdentity();
    glTranslatef( -1.5f, 0.0f, -6.0f );

    glBegin( GL_TRIANGLES );            /* Drawing Using Triangles */
      glVertex3f(  0.0f,  1.0f, 0.0f ); /* Top */
      glVertex3f( -1.0f, -1.0f, 0.0f ); /* Bottom Left */
      glVertex3f(  1.0f, -1.0f, 0.0f ); /* Bottom Right */
    glEnd( );                           /* Finished Drawing The Triangle */

    /* Move Right 3 Units */
    glTranslatef( 3.0f, 0.0f, 0.0f );

    glBegin( GL_QUADS );                /* Draw A Quad */
      glVertex3f( -1.0f,  1.0f, 0.0f ); /* Top Left */
      glVertex3f(  1.0f,  1.0f, 0.0f ); /* Top Right */
      glVertex3f(  1.0f, -1.0f, 0.0f ); /* Bottom Right */
      glVertex3f( -1.0f, -1.0f, 0.0f ); /* Bottom Left */
    glEnd( );                           /* Done Drawing The Quad */

    /* Draw it to the screen */
    SDL_GL_SwapBuffers( );

    /* Gather our frames per second */
    Frames++;
    {
	GLint t = SDL_GetTicks();
	if (t - T0 >= 5000) {
	    GLfloat seconds = (t - T0) / 1000.0;
	    GLfloat fps = Frames / seconds;
	    printf("%d frames in %g seconds = %g FPS\n", Frames, seconds, fps);
	    T0 = t;
	    Frames = 0;
	}
    }

    return( TRUE );
}

int main( int argc, char **argv )
{
    /* Flags to pass to SDL_SetVideoMode */
    int videoFlags;
    /* main loop variable */
    int done = FALSE;
    /* used to collect events */
    SDL_Event event;
    /* this holds some info about our display */
    const SDL_VideoInfo *videoInfo;
    /* whether or not the window is active */
    int isActive = TRUE;

    /* initialize SDL */
    if ( SDL_Init( SDL_INIT_VIDEO ) < 0 )
	{
	    fprintf( stderr, "Video initialization failed: %s\n",
		     SDL_GetError( ) );
	    Quit( 1 );
	}

    /* Fetch the video info */
    videoInfo = SDL_GetVideoInfo( );

    if ( !videoInfo )
	{
	    fprintf( stderr, "Video query failed: %s\n",
		     SDL_GetError( ) );
	    Quit( 1 );
	}

    /* the flags to pass to SDL_SetVideoMode */
    videoFlags  = SDL_OPENGL;          /* Enable OpenGL in SDL */
    videoFlags |= SDL_GL_DOUBLEBUFFER; /* Enable double buffering */
    videoFlags |= SDL_HWPALETTE;       /* Store the palette in hardware */
    videoFlags |= SDL_RESIZABLE;       /* Enable window resizing */

    /* This checks to see if surfaces can be stored in memory */
    if ( videoInfo->hw_available )
	videoFlags |= SDL_HWSURFACE;
    else
	videoFlags |= SDL_SWSURFACE;

    /* This checks if hardware blits can be done */
    if ( videoInfo->blit_hw )
	videoFlags |= SDL_HWACCEL;

    /* Sets up OpenGL double buffering */
    SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );

    /* get a SDL surface */
    surface = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP,
				videoFlags );

    /* Verify there is a surface */
    if ( !surface )
	{
	    fprintf( stderr,  "Video mode set failed: %s\n", SDL_GetError( ) );
	    Quit( 1 );
	}

    /* initialize OpenGL */
    initGL( );

    /* resize the initial window */
    resizeWindow( SCREEN_WIDTH, SCREEN_HEIGHT );

    /* wait for events */
    while ( !done )
	{
	    /* handle the events in the queue */

	    while ( SDL_PollEvent( &event ) )
		{
		    switch( event.type )
			{
			case SDL_ACTIVEEVENT:
			    /* Something's happend with our focus
			     * If we lost focus or we are iconified, we
			     * shouldn't draw the screen
			     */
			    if ( event.active.gain == 0 )
				isActive = FALSE;
			    else
				isActive = TRUE;
			    break;			    
			case SDL_VIDEORESIZE:
			    /* handle resize event */
			    surface = SDL_SetVideoMode( event.resize.w,
							event.resize.h,
							16, videoFlags );
			    if ( !surface )
				{
				    fprintf( stderr, "Could not get a surface after resize: %s\n", SDL_GetError( ) );
				    Quit( 1 );
				}
			    resizeWindow( event.resize.w, event.resize.h );
			    break;
			case SDL_KEYDOWN:
			    /* handle key presses */
			    handleKeyPress( &event.key.keysym );
			    break;
			case SDL_QUIT:
			    /* handle quit requests */
			    done = TRUE;
			    break;
			default:
			    break;
			}
		}

	    /* draw the scene */
	    if ( isActive )
		drawGLScene( );
	}

    /* clean ourselves up and exit */
    Quit( 0 );

    /* Should never get here */
    return( 0 );
}
[edited by - graveyard filla on May 19, 2004 3:47:33 AM]

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does anyone know why this is happening? i cant figure it out... i downloaded the "original" version (well actually the VS.net one) which was made for windows and uses GLUT/win32? and anyway, that one also does this same thing. im thinking maybe its a tiny bit fast but that could be in my head, but its still doing this same thing. does anyone know what the problem is? is this how its suposed to be? thanks for any help......

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i tried that already, and it didnt really make a difference... does anyone know why this is happening? kind of discouraging, i mean my SDL windows never did anything like this... thanks for any further help (incase its not clear, i only get this trailing effect for a second or 2 when i move the window below my screen, or if i resize it... thanks again)

[edited by - graveyard filla on May 20, 2004 4:04:32 PM]

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you might find your answer in the nehe oop basecode, when u get it to compile correctly that is

anyway the code basically just calls the draw scene function while ur resizing. I played around with it and didnt get any artifacts like your experiencing....

so give it a go!

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I just don''t think the drawing function is called for some reason, of course i might be completely wrong, try using a log file or something.

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