Click here to Skip to main content
Rate this: bad
good
Please Sign up or sign in to vote.
See more: C++ OpenGL
I have been facing a problem regarding selecting the space in negative z direction with glulookat function. my code works fine for selecting a space providing two digonal points in the workspace if either one has positive z value but if both of the z value is negative the code fails.
 
void COpenGLBaseView::Select(float x1,float y1, float z1,float x2,float y2,float z2)
{	
	if(x1 > x2)
	{
		Swap(x1,x2);
	}
	if(y1 > y2)
	{
		Swap(y1,y2);
	}
	if(z1 > z2)
	{
		Swap(z1,z2);
	}
	GLint hits, view[4];
	/* This choose the buffer where store the values for the selection data */
	glSelectBuffer(m_BucketSize, m_aBucket);
	/*	 This retrieve info about the viewport */
	glGetIntegerv(GL_VIEWPORT, view);
	/*	 Switching in selecton mode	 */
	glRenderMode(GL_SELECT);
	/*	 Clearing the name's stack
	This stack contains all the info about the objects */
	glInitNames();
	/*	 Now fill the stack with one element (or glLoadName will generate an error) */
	glPushName(0);
	/*	 Now modify the vieving volume, restricting selection area around the cursor	 */
	glMatrixMode(GL_PROJECTION);
	glPushMatrix();
	glLoadIdentity();
	/*restrict the draw to an area around the cursor	 */
	//gluPickMatrix(X+XRange * 0.5, Y+YRange * 0.5, XRange, YRange, view);
	gluPickMatrix(m_cx  * 0.5, m_cy * 0.5,m_cx, m_cy, view);
 
	glOrtho(x1,x2,y1,y2,z1,z2);
	/*	 Draw the objects onto the screen*/
	glMatrixMode(GL_MODELVIEW);	 
	glLoadIdentity();
 
	//gluLookAt(0.0,0.0,z2+z1, 0.0 , 0.0 ,z1,0.0,1.0,0.0);

	
	if(z1<0 && z2<0)
	{
		gluLookAt(0.0,0.0,-(z1+z2), 0.0 , 0.0 ,-(z1+z2),0.0,1.0,z1);  // I          want value to work for this condition.
	}
	else
	{
		gluLookAt(0.0,0.0,z1+z2, 0.0 , 0.0 ,z1,0.0,1.0,0.0);
	}
	
	//gluLookAt(0.0,0.0,z1+z2, 0.0 , 0.0 ,z1-1,0.0,1.0,0.0);
	/*	 draw only the names in the stack, and fill the array*/		
	m_pContour->RenderSelection(); 
	/* Do you remeber? We do pushMatrix in PROJECTION mode */
	glMatrixMode(GL_PROJECTION);
	glPopMatrix();
	/* get number of objects drawed in that area and return to render mode */
	hits = glRenderMode(GL_RENDER);
	glMatrixMode(GL_MODELVIEW);	
	/*if(hits > 0)
	{
	int selIndex = buff[3];
	return selIndex;
	}
	return -1;*/
 
	/*
	For each hit in the buffer are allocated 4 bytes:
	1. Number of hits selected (always one,
	beacuse when we draw each object
	we use glLoadName, so we replace the
	prevous name in the stack)
	2. Min Z
	3. Max Z
	4. Name of the hit (glLoadName)
	*/
	// return hits;

	int SelectedNum  = hits;	
	if(SelectedNum > 0)
	{
		for(int i = 0;i < SelectedNum; ++i)
		{
			m_SelectedParticles.push_back(m_aBucket[i * 4 + 3]);
			if(TM_SELECT_REGION_DIRECT)
			{
				m_SelectedParticlesToSeeParticleFlow.insert(m_aBucket[i * 4 + 3]);
			}
		}
	}
	if(TM_SELECT_REGION_DIRECT)
	{
		m_SelectedParticles.clear();
		set<int>::iterator it;
		for(it= m_SelectedParticlesToSeeParticleFlow.begin(); it!= m_SelectedParticlesToSeeParticleFlow.end(); it++)
		{
			m_SelectedParticles.push_back(*it);
		}		
	}
	glLoadIdentity();
	SetupViewingTransform();
	Invalidate(false);
}
//************** End Selection in 3D**********************//

bool COpenGLBaseView::CompareFramewithTrackValue(int trackValue,bool checkStepForward)
{
	if(checkStepForward)
	{
		if(trackValue<frameNumber)
		{
			return true;
		}
	}
	else 
	{
		if(trackValue>initialframeNumber)
		{
			return true;
		}
	}	
	
	return false;
}
 
could any one please help.
Posted 10-Sep-12 17:26pm
amsainju1.3K

1 solution

Rate this: bad
good
Please Sign up or sign in to vote.

Solution 1

this code had no problem, the issue was with glulookat function.
I tried changing some parameter and the problem was solved.
  Permalink  

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

  Print Answers RSS
0 OriginalGriff 562
1 Sergey Alexandrovich Kryukov 484
2 Maciej Los 325
3 DamithSL 233
4 Mathew Soji 195
0 OriginalGriff 7,168
1 Sergey Alexandrovich Kryukov 6,377
2 DamithSL 5,461
3 Manas Bhardwaj 4,876
4 Maciej Los 4,450


Advertise | Privacy | Mobile
Web04 | 2.8.1411023.1 | Last Updated 27 Jun 2013
Copyright © CodeProject, 1999-2014
All Rights Reserved. Terms of Service
Layout: fixed | fluid

CodeProject, 503-250 Ferrand Drive Toronto Ontario, M3C 3G8 Canada +1 416-849-8900 x 100