C++ qglReadPixels函数代码示例

// "filename" param is something like "screenshots/shot0000.tga"
//	note that if the last extension is ".jpg", then it'll save a JPG, else TGA
//
void R_TakeScreenshot( int x, int y, int width, int height, char *fileName ) {
#ifndef _XBOX
	byte		*buffer;
	int			i, c, temp;

	qboolean bSaveAsJPG = !strnicmp(&fileName[strlen(fileName)-4],".jpg",4);

	if (bSaveAsJPG)
	{
		// JPG saver expects to be fed RGBA data, though it presumably ignores 'A'...
		//
		buffer = (unsigned char *) Z_Malloc(glConfig.vidWidth*glConfig.vidHeight*4, TAG_TEMP_WORKSPACE, qfalse);
		qglReadPixels( x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer ); 

		// gamma correct
		if ( tr.overbrightBits>0 && glConfig.deviceSupportsGamma ) {
			R_GammaCorrect( buffer, glConfig.vidWidth * glConfig.vidHeight * 4 );
		}

		SaveJPG(fileName, 95, width, height, buffer);
	}
	else
	{
		// TGA...
		//
		buffer = (unsigned char *) Z_Malloc(glConfig.vidWidth*glConfig.vidHeight*3 + 18, TAG_TEMP_WORKSPACE, qfalse);
		memset (buffer, 0, 18);
		buffer[2] = 2;		// uncompressed type
		buffer[12] = width & 255;
		buffer[13] = width >> 8;
		buffer[14] = height & 255;
		buffer[15] = height >> 8;
		buffer[16] = 24;	// pixel size

		qglReadPixels( x, y, width, height, GL_RGB, GL_UNSIGNED_BYTE, buffer+18 ); 

		// swap rgb to bgr
		c = 18 + width * height * 3;
		for (i=18 ; i<c ; i+=3) {
			temp = buffer[i];
			buffer[i] = buffer[i+2];
			buffer[i+2] = temp;
		}

		// gamma correct
		if ( tr.overbrightBits>0 && glConfig.deviceSupportsGamma ) {
			R_GammaCorrect( buffer + 18, glConfig.vidWidth * glConfig.vidHeight * 3 );
		}
		FS_WriteFile( fileName, buffer, c );
	}
	
	Z_Free( buffer );
#endif
}

/* 
================== 
GL_ScreenShot_f
================== 
*/  
void GL_ScreenShot_f (void) 
{
	byte		*buffer;
#ifdef WIN32
	DWORD tID;
#endif

	buffer = malloc(vid.width*vid.height*3);

	qglReadPixels (0, 0, vid.width, vid.height, GL_RGB, GL_UNSIGNED_BYTE, buffer ); 
#ifdef WIN32
	if (!strcmp (ri.Cmd_Argv(1), "jpg"))
	{
		GL_ScreenShot_JPG (buffer);
	}
	else
	{
#ifdef USE_THREADS
		//_beginthreadex (NULL, 0, (unsigned int (__stdcall *)(void *))png_write_thread, (void *)buffer, 0, &tID);
		CreateThread (NULL, 0, (LPTHREAD_START_ROUTINE)png_write_thread, (LPVOID)buffer, 0, &tID);
		ri.Con_Printf (PRINT_ALL, "Taking PNG screenshot...\n");
#else
		png_write_thread (buffer);
#endif
	}
#else
	GL_ScreenShot_JPG (buffer);
#endif
} 

/*
=======================================================================================================================================
RB_TestFlare
=======================================================================================================================================
*/
void RB_TestFlare(flare_t *f) {
	float			depth;
	qboolean visible;
	float			fade;
	float			screenZ;
	FBO_t           *oldFbo;

	backEnd.pc.c_flareTests++;

	// doing a readpixels is as good as doing a glFinish(), so
	// don't bother with another sync
	glState.finishCalled = qfalse;

	// if we're doing multisample rendering, read from the correct FBO
	oldFbo = glState.currentFBO;
	if (tr.msaaResolveFbo)
	{
		FBO_Bind(tr.msaaResolveFbo);
	}

	// read back the z buffer contents
	qglReadPixels(f->windowX, f->windowY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &depth);

	// if we're doing multisample rendering, switch to the old FBO
	if (tr.msaaResolveFbo)
	{
		FBO_Bind(oldFbo);
	}

	screenZ = backEnd.viewParms.projectionMatrix[14] / 
		((2*depth - 1) * backEnd.viewParms.projectionMatrix[11] - backEnd.viewParms.projectionMatrix[10]);

	visible = (qboolean)(f->flags & 1);

	if (-f->eyeZ - -screenZ  > 24)
		visible = qfalse;

	if (visible) {
		if (!f->visible) {
			f->visible = qtrue;
			f->fadeTime = backEnd.refdef.time - 1;
		}
		fade = ((backEnd.refdef.time - f->fadeTime) /1000.0f) * r_flareFade->value;
	} else {
		if (f->visible) {
			f->visible = qfalse;
			f->fadeTime = backEnd.refdef.time - 1;
		}
		fade = 1.0f - ((backEnd.refdef.time - f->fadeTime) / 1000.0f) * r_flareFade->value;
	}

	if (fade < 0) {
		fade = 0;
	}
	if (fade > 1) {
		fade = 1;
	}

	f->drawIntensity = fade;
}

void R_LevelShot( void ) {
#ifndef _XBOX
	char		checkname[MAX_OSPATH];
	byte		*buffer;
	byte		*source;
	byte		*src, *dst;
	int			x, y;
	int			r, g, b;
	float		xScale, yScale;
	int			xx, yy;

	sprintf( checkname, "levelshots/%s.tga", tr.worldDir + strlen("maps/") );

	source = (byte*) Z_Malloc( glConfig.vidWidth * glConfig.vidHeight * 3, TAG_TEMP_WORKSPACE, qfalse );

	buffer = (byte*) Z_Malloc( LEVELSHOTSIZE * LEVELSHOTSIZE*3 + 18, TAG_TEMP_WORKSPACE, qfalse );
	memset (buffer, 0, 18);
	buffer[2] = 2;		// uncompressed type
	buffer[12] = LEVELSHOTSIZE & 255;
	buffer[13] = LEVELSHOTSIZE >> 8;
	buffer[14] = LEVELSHOTSIZE & 255;
	buffer[15] = LEVELSHOTSIZE >> 8;
	buffer[16] = 24;	// pixel size

	qglReadPixels( 0, 0, glConfig.vidWidth, glConfig.vidHeight, GL_RGB, GL_UNSIGNED_BYTE, source ); 

	// resample from source
	xScale = glConfig.vidWidth / (4.0*LEVELSHOTSIZE);
	yScale = glConfig.vidHeight / (3.0*LEVELSHOTSIZE);
	for ( y = 0 ; y < LEVELSHOTSIZE ; y++ ) {
		for ( x = 0 ; x < LEVELSHOTSIZE ; x++ ) {
			r = g = b = 0;
			for ( yy = 0 ; yy < 3 ; yy++ ) {
				for ( xx = 0 ; xx < 4 ; xx++ ) {
					src = source + 3 * ( glConfig.vidWidth * (int)( (y*3+yy)*yScale ) + (int)( (x*4+xx)*xScale ) );
					r += src[0];
					g += src[1];
					b += src[2];
				}
			}
			dst = buffer + 18 + 3 * ( y * LEVELSHOTSIZE + x );
			dst[0] = b / 12;
			dst[1] = g / 12;
			dst[2] = r / 12;
		}
	}

	// gamma correct
	if ( glConfig.deviceSupportsGamma ) {
		R_GammaCorrect( buffer + 18, LEVELSHOTSIZE * LEVELSHOTSIZE * 3 );
	}

	FS_WriteFile( checkname, buffer, LEVELSHOTSIZE * LEVELSHOTSIZE*3 + 18 );

	Z_Free( buffer );
	Z_Free( source );

	VID_Printf( PRINT_ALL, "Wrote %s\n", checkname );
#endif
}

/*
==================
RB_ReadPixels

Reads an image but takes care of alignment issues for reading RGB images.

Reads a minimum offset for where the RGB data starts in the image from
integer stored at pointer offset. When the function has returned the actual
offset was written back to address offset. This address will always have an
alignment of packAlign to ensure efficient copying.

Stores the length of padding after a line of pixels to address padlen

Return value must be freed with ri.Hunk_FreeTempMemory()
==================
*/
byte *RB_ReadPixels(int x, int y, int width, int height, size_t *offset, int *padlen)
{
	byte  *buffer, *bufstart;
	int   padwidth, linelen;
	GLint packAlign;

	qglGetIntegerv(GL_PACK_ALIGNMENT, &packAlign);

	linelen  = width * 3;
	padwidth = PAD(linelen, packAlign);

	// Allocate a few more bytes so that we can choose an alignment we like
	buffer = ri.Hunk_AllocateTempMemory(padwidth * height + *offset + packAlign - 1);

	bufstart = buffer;
	padwidth = linelen;
	int p2width = 1, p2height = 1;
	int xx, yy, aa;
	while (p2width < glConfig.vidWidth)
		p2width *= 2;
	while (p2height < glConfig.vidHeight)
		p2height *= 2;
	byte *source = (byte *) ri.Hunk_AllocateTempMemory(p2width * p2height * 4);
	qglReadPixels(0, 0, p2width, p2height, GL_RGBA, GL_UNSIGNED_BYTE, source);
	for (yy = y; yy < height; yy++)
		for (xx = x; xx < width; xx++)
			for (aa = 0; aa < 3; aa++)
				buffer[yy * width * 3 + xx * 3 + aa] = source[(yy + y) * p2width * 4 + (xx + x) * 4 + aa];
	ri.Hunk_FreeTempMemory(source);

	*offset = bufstart - buffer;
	*padlen = padwidth - linelen;

	return buffer;
}

static void R_LevelShot( void ) {
#ifndef _XBOX
    char		checkname[MAX_OSPATH];
    byte		*buffer;
    byte		*source;
    byte		*src, *dst;
    int			x, y;
    int			r, g, b;
    float		xScale, yScale;
    int			xx, yy;

    sprintf( checkname, "levelshots/%s.tga", tr.world->baseName );

    source = (unsigned char *)Hunk_AllocateTempMemory( glConfig.vidWidth * glConfig.vidHeight * 3 );

    buffer = (unsigned char *)Hunk_AllocateTempMemory( LEVELSHOTSIZE * LEVELSHOTSIZE*3 + 18);
    Com_Memset (buffer, 0, 18);
    buffer[2] = 2;		// uncompressed type
    buffer[12] = LEVELSHOTSIZE & 255;
    buffer[13] = LEVELSHOTSIZE >> 8;
    buffer[14] = LEVELSHOTSIZE & 255;
    buffer[15] = LEVELSHOTSIZE >> 8;
    buffer[16] = 24;	// pixel size

    qglReadPixels( 0, 0, glConfig.vidWidth, glConfig.vidHeight, GL_RGB, GL_UNSIGNED_BYTE, source );

    // resample from source
    xScale = glConfig.vidWidth / (4.0*LEVELSHOTSIZE);
    yScale = glConfig.vidHeight / (3.0*LEVELSHOTSIZE);
    for ( y = 0 ; y < LEVELSHOTSIZE ; y++ ) {
        for ( x = 0 ; x < LEVELSHOTSIZE ; x++ ) {
            r = g = b = 0;
            for ( yy = 0 ; yy < 3 ; yy++ ) {
                for ( xx = 0 ; xx < 4 ; xx++ ) {
                    src = source + 3 * ( glConfig.vidWidth * (int)( (y*3+yy)*yScale ) + (int)( (x*4+xx)*xScale ) );
                    r += src[0];
                    g += src[1];
                    b += src[2];
                }
            }
            dst = buffer + 18 + 3 * ( y * LEVELSHOTSIZE + x );
            dst[0] = b / 12;
            dst[1] = g / 12;
            dst[2] = r / 12;
        }
    }

    // gamma correct
    if ( ( tr.overbrightBits > 0 ) && glConfig.deviceSupportsGamma ) {
        R_GammaCorrect( buffer + 18, LEVELSHOTSIZE * LEVELSHOTSIZE * 3 );
    }

    FS_WriteFile( checkname, buffer, LEVELSHOTSIZE * LEVELSHOTSIZE*3 + 18 );

    Hunk_FreeTempMemory( buffer );
    Hunk_FreeTempMemory( source );

    Com_Printf ("Wrote %s\n", checkname );
#endif
}

/* 
================== 
R_TakeScreenshot
================== 
*/  
void R_TakeScreenshot( int x, int y, int width, int height, char *fileName ) {
	byte		*buffer;
	int			i, c, temp;

	buffer = (unsigned char *)Hunk_AllocateTempMemory(glConfig.vidWidth*glConfig.vidHeight*3+18);

	Com_Memset (buffer, 0, 18);
	buffer[2] = 2;		// uncompressed type
	buffer[12] = width & 255;
	buffer[13] = width >> 8;
	buffer[14] = height & 255;
	buffer[15] = height >> 8;
	buffer[16] = 24;	// pixel size

	qglReadPixels( x, y, width, height, GL_RGB, GL_UNSIGNED_BYTE, buffer+18 ); 

	// swap rgb to bgr
	c = 18 + width * height * 3;
	for (i=18 ; i<c ; i+=3) {
		temp = buffer[i];
		buffer[i] = buffer[i+2];
		buffer[i+2] = temp;
	}

	// gamma correct
	if ( ( tr.overbrightBits > 0 ) && glConfig.deviceSupportsGamma ) {
		R_GammaCorrect( buffer + 18, glConfig.vidWidth * glConfig.vidHeight * 3 );
	}

	FS_WriteFile( fileName, buffer, c );

	Hunk_FreeTempMemory( buffer );
}

/*
==============
CaptureRenderToFile

==============
*/
void idRenderSystemLocal::CaptureRenderToFile( const char *fileName, bool fixAlpha ) {
	if ( !glConfig.isInitialized ) {
		return;
	}

	renderCrop_t *rc = &renderCrops[currentRenderCrop];

	guiModel->EmitFullScreen();
	guiModel->Clear();
	R_IssueRenderCommands();

	qglReadBuffer( GL_BACK );

	// include extra space for OpenGL padding to word boundaries
	int	c = ( rc->width + 3 ) * rc->height;
	byte *data = (byte *)R_StaticAlloc( c * 3 );
	
	qglReadPixels( rc->x, rc->y, rc->width, rc->height, GL_RGB, GL_UNSIGNED_BYTE, data ); 

	byte *data2 = (byte *)R_StaticAlloc( c * 4 );

	for ( int i = 0 ; i < c ; i++ ) {
		data2[ i * 4 ] = data[ i * 3 ];
		data2[ i * 4 + 1 ] = data[ i * 3 + 1 ];
		data2[ i * 4 + 2 ] = data[ i * 3 + 2 ];
		data2[ i * 4 + 3 ] = 0xff;
	}

	R_WriteTGA( fileName, data2, rc->width, rc->height, true );

	R_StaticFree( data );
	R_StaticFree( data2 );
}

/*
=============
RB_ExportCubemaps

=============
*/
const void *RB_ExportCubemaps(const void *data)
{
	const exportCubemapsCommand_t *cmd = data;

	// finish any 2D drawing if needed
	if (tess.numIndexes)
		RB_EndSurface();

	if (!glRefConfig.framebufferObject || !tr.world || tr.numCubemaps == 0)
	{
		// do nothing
		ri.Printf(PRINT_ALL, "Nothing to export!\n");
		return (const void *)(cmd + 1);
	}

	if (cmd)
	{
		FBO_t *oldFbo = glState.currentFBO;
		int sideSize = r_cubemapSize->integer * r_cubemapSize->integer * 4;
		byte *cubemapPixels = ri.Malloc(sideSize * 6);
		int i, j;

		FBO_Bind(tr.renderCubeFbo);

		for (i = 0; i < tr.numCubemaps; i++)
		{
			char filename[MAX_QPATH];
			cubemap_t *cubemap = &tr.cubemaps[i];
			byte *p = cubemapPixels;

			for (j = 0; j < 6; j++)
			{
				FBO_AttachImage(tr.renderCubeFbo, cubemap->image, GL_COLOR_ATTACHMENT0_EXT, j);
				qglReadPixels(0, 0, r_cubemapSize->integer, r_cubemapSize->integer, GL_RGBA, GL_UNSIGNED_BYTE, p);
				p += sideSize;
			}

			if (cubemap->name[0])
			{
				COM_StripExtension(cubemap->name, filename, MAX_QPATH);
				Q_strcat(filename, MAX_QPATH, ".dds");
			}
			else
			{
				Com_sprintf(filename, MAX_QPATH, "cubemaps/%s/%03d.dds", tr.world->baseName, i);
			}

			R_SaveDDS(filename, cubemapPixels, r_cubemapSize->integer, r_cubemapSize->integer, 6);
			ri.Printf(PRINT_ALL, "Saved cubemap %d as %s\n", i, filename);
		}

		FBO_Bind(oldFbo);

		ri.Free(cubemapPixels);
	}

	return (const void *)(cmd + 1);
}

int R_MME_MultiPassNext (qboolean useMain)
{
	mmeBlurControl_t *control;
	shotData_t *shotData;
	passData_t *passData;
	byte* outAlloc;
	__m64 *outAlign;
	//int i;

	if (useMain) {
		control = &passDataMain.control;
		shotData = &shotDataMain;
		passData = &passDataMain;
	} else {
		control = &passDataLeft.control;
		shotData = &shotDataLeft;
		passData = &passDataLeft;
	}

	if ( !control->totalFrames )
		return 0;

	if (shotData->allocFailed) {
		return 0;
	}

	outAlloc = ri.Hunk_AllocateTempMemory( shotData->pixelCount * 3 + 16);
	outAlign = (__m64 *)((((int)(outAlloc)) + 15) & ~15);

	// don't call GLimp_EndFrame()

	//qglReadPixels(0, 0, glConfig.vidWidth, glConfig.vidHeight, GL_BGR, GL_UNSIGNED_BYTE, outAlign);
	qglReadPixels(0, 0, glConfig.vidWidth, glConfig.vidHeight, GL_RGB, GL_UNSIGNED_BYTE, outAlign);

	// testing
#if 0
	for (i = 0;  i < glConfig.vidWidth * glConfig.vidHeight * 3;  i++) {
		((byte *)outAlign)[i] += i;
	}
#endif

	R_MME_BlurAccumAdd( &passData->dof, outAlign );

	ri.Hunk_FreeTempMemory( outAlloc );
	if ( ++(control->totalIndex) < control->totalFrames ) {
		int nextIndex = control->totalIndex;

		if ( ++(nextIndex) >= control->totalFrames ) {
			// pass
		}
		return 1;
	}
	control->totalIndex = 0;
	R_MME_BlurAccumShift( &passData->dof );
	return 0;
}

/*
====================
R_LevelShot

levelshots are specialized 128*128 thumbnails for
the menu system, sampled down from full screen distorted images
====================
*/
void R_LevelShot( void ) {
	char		checkname[MAX_OSPATH];
	byte		*buffer;
	byte		*source;
	byte		*src, *dst;
	int			x, y;
	int			r, g, b;
	float		xScale, yScale;
	int			xx, yy;

	sprintf( checkname, "levelshots/%s.tga", tr.world->baseName );

	source = ri.Hunk_AllocateTempMemory( glConfig.vidWidth * glConfig.vidHeight * 3 );

	buffer = ri.Hunk_AllocateTempMemory( 128 * 128*3 + 18);
	Com_Memset (buffer, 0, 18);
	buffer[2] = 2;		// uncompressed type
	buffer[12] = 128;
	buffer[14] = 128;
	buffer[16] = 24;	// pixel size

	qglReadPixels( 0, 0, glConfig.vidWidth, glConfig.vidHeight, GL_RGB, GL_UNSIGNED_BYTE, source ); 

	// resample from source
	xScale = glConfig.vidWidth / 512.0f;
	yScale = glConfig.vidHeight / 384.0f;
	for ( y = 0 ; y < 128 ; y++ ) {
		for ( x = 0 ; x < 128 ; x++ ) {
			r = g = b = 0;
			for ( yy = 0 ; yy < 3 ; yy++ ) {
				for ( xx = 0 ; xx < 4 ; xx++ ) {
					src = source + 3 * ( glConfig.vidWidth * (int)( (y*3+yy)*yScale ) + (int)( (x*4+xx)*xScale ) );
					r += src[0];
					g += src[1];
					b += src[2];
				}
			}
			dst = buffer + 18 + 3 * ( y * 128 + x );
			dst[0] = b / 12;
			dst[1] = g / 12;
			dst[2] = r / 12;
		}
	}

	// gamma correct
	if ( ( tr.overbrightBits > 0 ) && glConfig.deviceSupportsGamma ) {
		R_GammaCorrect( buffer + 18, 128 * 128 * 3 );
	}

	ri.FS_WriteFile( checkname, buffer, 128 * 128*3 + 18 );

	ri.Hunk_FreeTempMemory( buffer );
	ri.Hunk_FreeTempMemory( source );

	ri.Printf( PRINT_ALL, "Wrote %s\n", checkname );
}

void R_MME_GetMultiShot (byte * target, int width, int height, int glMode)
{
	if ( !passDataMain.control.totalFrames ) {
		//R_MME_GetShot( target, shotData.main.type );
		qglReadPixels(0, 0, width, height, glMode, GL_UNSIGNED_BYTE, target);
	} else {
		//Com_Memcpy( target, passDataMain.dof.accum, mainData.pixelCount * 3 );
		Com_Memcpy( target, passDataMain.dof.accum, shotDataMain.pixelCount * 3 );
	}
}

/*
==================
RB_TestFlare
==================
*/
static void RB_TestFlare( flare_t *f ) {
	float			depth;
	qboolean		visible;
	float			fade;
	float			screenZ;

	if (f->fadeTime == -666)
		{
			RB_TestFlareFast(f);
			return;
		}

	backEnd.pc.c_flareTests++;


	// doing a readpixels is as good as doing a glFinish(), so
	// don't bother with another sync
	glState.finishCalled = qfalse;

	// read back the z buffer contents

	qglReadPixels( f->windowX, f->windowY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &depth );

	screenZ = backEnd.viewParms.projectionMatrix[14] / 
		( ( 2*depth - 1 ) * backEnd.viewParms.projectionMatrix[11] - backEnd.viewParms.projectionMatrix[10] );

	visible = ( -f->eyeZ - -screenZ ) < 24;



	if ( visible ) {
		if ( !f->visible ) {
			f->visible = qtrue;
			f->fadeTime = backEnd.refdef.time - 1;
		}
		{
			fade = ( ( backEnd.refdef.time - f->fadeTime ) / 1000.0f ) * r_flareFade->value;
		}
	} else {
		if ( f->visible ) {
			f->visible = qfalse;
			f->fadeTime = backEnd.refdef.time - 1;
		}
		fade = 1.0f - ( ( backEnd.refdef.time - f->fadeTime ) / 1000.0f ) * r_flareFade->value;
	}

	if ( fade < 0 ) {
		fade = 0;
	}
	if ( fade > 1 ) {
		fade = 1;
	}

	f->drawIntensity = fade;
}

/**
 * @brief RB_SwapBuffers
 * @param[in] data
 * @return
 */
const void *RB_SwapBuffers(const void *data)
{
	const swapBuffersCommand_t *cmd;

	// finish any 2D drawing if needed
	if (tess.numIndexes)
	{
		RB_EndSurface();
	}

	// texture swapping test
	if (r_showImages->integer)
	{
		RB_ShowImages();
	}

	RB_GammaScreen();

	cmd = ( const swapBuffersCommand_t * ) data;

	// we measure overdraw by reading back the stencil buffer and
	// counting up the number of increments that have happened
	if (r_measureOverdraw->integer)
	{
		int           i;
		long          sum = 0;
		unsigned char *stencilReadback;

		stencilReadback = ri.Hunk_AllocateTempMemory(glConfig.vidWidth * glConfig.vidHeight);
		qglReadPixels(0, 0, glConfig.vidWidth, glConfig.vidHeight, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, stencilReadback);

		for (i = 0; i < glConfig.vidWidth * glConfig.vidHeight; i++)
		{
			sum += stencilReadback[i];
		}

		backEnd.pc.c_overDraw += sum;
		ri.Hunk_FreeTempMemory(stencilReadback);
	}

	if (!glState.finishCalled)
	{
		qglFinish();
	}

	Ren_LogComment("***************** RB_SwapBuffers *****************\n\n\n");

	ri.GLimp_SwapFrame();

	backEnd.projection2D = qfalse;

	return ( const void * ) (cmd + 1);
}

/* 
================== 
R_TakeScreenshot
================== 
*/  
void R_TakeScreenshotJPEG( int x, int y, int width, int height, char *fileName ) {
	byte		*buffer;

	buffer = (unsigned char *)Hunk_AllocateTempMemory(glConfig.vidWidth*glConfig.vidHeight*4);

	qglReadPixels( x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer ); 

	// gamma correct
	if ( ( tr.overbrightBits > 0 ) && glConfig.deviceSupportsGamma ) {
		R_GammaCorrect( buffer, glConfig.vidWidth * glConfig.vidHeight * 4 );
	}

	FS_WriteFile( fileName, buffer, 1 );		// create path
	SaveJPG( fileName, 95, glConfig.vidWidth, glConfig.vidHeight, buffer);

	Hunk_FreeTempMemory( buffer );
}