openni example NiViewer opengl block

在linux ubuntu 16.04 LTS 上測試，發現openNI 的NiViewer 會阻塞在opengl的函式，如：glclear。



void drawFrame()
{
	// calculate locations
	g_DrawConfig.DepthLocation.uBottom = 0;
	g_DrawConfig.DepthLocation.uTop = g_NonFullWinSize.Y - 1;
	g_DrawConfig.DepthLocation.uLeft = 0;
	g_DrawConfig.DepthLocation.uRight = g_NonFullWinSize.X - 1;

	g_DrawConfig.ColorLocation.uBottom = 0;
	g_DrawConfig.ColorLocation.uTop = g_NonFullWinSize.Y - 1;
	g_DrawConfig.ColorLocation.uLeft = 0;
	g_DrawConfig.ColorLocation.uRight = g_NonFullWinSize.X - 1;




	if (g_DrawConfig.Streams.ScreenArrangement == SIDE_BY_SIDE)
	{
		g_DrawConfig.DepthLocation.uRight = g_NonFullWinSize.X / 2 - 1;
		g_DrawConfig.ColorLocation.uLeft = g_NonFullWinSize.X / 2;
	}

	// Texture map init
	openni::VideoFrameRef* pDepthMD = &getDepthFrame();
	if (isDepthOn() && pDepthMD->isValid())
	{
		TextureMapInit(&g_texDepth, pDepthMD->getVideoMode().getResolutionX(), pDepthMD->getVideoMode().getResolutionY(), 4, pDepthMD->getWidth(), pDepthMD->getHeight());
		fixLocation(&g_DrawConfig.DepthLocation, pDepthMD->getVideoMode().getResolutionX(), pDepthMD->getVideoMode().getResolutionY());
	}

	openni::VideoFrameRef* pImageMD = NULL;

	if (isColorOn())
	{
		pImageMD = &getColorFrame();
	}
 	else if (isIROn())
 	{
 		pImageMD = &getIRFrame();
 	}

	if (pImageMD != NULL && pImageMD->isValid())
	{
		TextureMapInit(&g_texColor, pImageMD->getVideoMode().getResolutionX(), pImageMD->getVideoMode().getResolutionY(), 4, pImageMD->getWidth(), pImageMD->getHeight());
		fixLocation(&g_DrawConfig.ColorLocation, pImageMD->getVideoMode().getResolutionX(), pImageMD->getVideoMode().getResolutionY());
	}

	// check if pointer is over a map
	bool bOverDepth = (pDepthMD != NULL && pDepthMD->isValid()) && isPointInRect(g_DrawUserInput.Cursor, &g_DrawConfig.DepthLocation);
	bool bOverImage = (pImageMD != NULL && pImageMD->isValid()) && isPointInRect(g_DrawUserInput.Cursor, &g_DrawConfig.ColorLocation);
	bool bDrawDepthPointer = false;
	bool bDrawImagePointer = false;
	int imagePointerRed = 255;
	int imagePointerGreen = 0;
	int imagePointerBlue = 0;

	IntPair pointerInDepth = {0,0};
	IntPair pointerInColor = {0,0};

	if (bOverImage)
	{
		pointerInColor.X = (double)(g_DrawUserInput.Cursor.X - g_DrawConfig.ColorLocation.uLeft) / (g_DrawConfig.ColorLocation.uRight - g_DrawConfig.ColorLocation.uLeft + 1) * pImageMD->getVideoMode().getResolutionX();
		pointerInColor.Y = (double)(g_DrawUserInput.Cursor.Y - g_DrawConfig.ColorLocation.uBottom) / (g_DrawConfig.ColorLocation.uTop - g_DrawConfig.ColorLocation.uBottom + 1) * pImageMD->getVideoMode().getResolutionY();
		bDrawImagePointer = true;
	}

	if (bOverDepth)
	{
		pointerInDepth.X = (double)(g_DrawUserInput.Cursor.X - g_DrawConfig.DepthLocation.uLeft) / (g_DrawConfig.DepthLocation.uRight - g_DrawConfig.DepthLocation.uLeft + 1) * pDepthMD->getVideoMode().getResolutionX();
		pointerInDepth.Y = (double)(g_DrawUserInput.Cursor.Y - g_DrawConfig.DepthLocation.uBottom) / (g_DrawConfig.DepthLocation.uTop - g_DrawConfig.DepthLocation.uBottom + 1) * pDepthMD->getVideoMode().getResolutionY();
		bDrawDepthPointer = true;

		if (!bOverImage && g_DrawConfig.bShowPointer &&
			pointerInDepth.X >= pDepthMD->getCropOriginX() && pointerInDepth.X < (pDepthMD->getCropOriginX() + pDepthMD->getWidth()) &&
			pointerInDepth.Y >= pDepthMD->getCropOriginY() && pointerInDepth.Y < (pDepthMD->getCropOriginY() + pDepthMD->getHeight()))
		{

			// try to translate depth pixel to image
			openni::DepthPixel* pDepthPixels = (openni::DepthPixel*)pDepthMD->getData();
			openni::DepthPixel pointerDepth = pDepthPixels[(pointerInDepth.Y - pDepthMD->getCropOriginY()) * pDepthMD->getWidth() + (pointerInDepth.X - pDepthMD->getCropOriginX())];
			if (convertDepthPointToColor(pointerInDepth.X, pointerInDepth.Y, pointerDepth, &pointerInColor.X, &pointerInColor.Y))
			{
				bDrawImagePointer = true;
				imagePointerRed = 0;
				imagePointerGreen = 0;
				imagePointerBlue = 255;
			}
		}
	}

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

	// Setup the opengl env for fixed location view
	glMatrixMode(GL_PROJECTION);
	glPushMatrix();
	glLoadIdentity();
	glOrtho(0,g_NonFullWinSize.X,g_NonFullWinSize.Y,0,-1.0,1.0);
	glDisable(GL_DEPTH_TEST); 

	if (g_DrawConfig.Streams.Depth.Coloring == CYCLIC_RAINBOW_HISTOGRAM || g_DrawConfig.Streams.Depth.Coloring == LINEAR_HISTOGRAM || g_DrawConfig.bShowPointer)
		calculateHistogram();

	drawColor(&g_DrawConfig.ColorLocation, bDrawImagePointer ? &pointerInColor : NULL, imagePointerRed, imagePointerGreen, imagePointerBlue);

	drawDepth(&g_DrawConfig.DepthLocation, bDrawDepthPointer ? &pointerInDepth : NULL);

	printRecordingInfo();

	if (g_DrawConfig.bShowPointer){
		drawPointerMode(bOverDepth ? &pointerInDepth : NULL);
	    drawUserInput(!bOverDepth && !bOverImage);
	}

	if(isPointInRect(g_DrawUserInput.Cursor, &g_DrawConfig.DepthLocation)){
	   drawUserdrag(bOverDepth ? &pointerInDepth : NULL);
	}

	drawUserMessage();
	drawPlaybackSpeed();

	if (g_DrawConfig.strErrorState[0] != '\0')
		drawErrorState();

	if (g_DrawConfig.bHelp)
		drawHelpScreen();

	glutSwapBuffers();
}