glDepthFunc(GL_GREATER) Function

[iris_raj]

Dear OpenglProgrammers,

Below is a picec code for displaying two simple primiitives. Initially I choose GL_LESS as my
DepthFunc, Polygon got rendered first and then triangle.But When I choose GL_GREATER, nothing is getting rendered.

What is the reason?

Also I want to know which Hidden Surface Removal algorithm is being used internally by Opengl .

void InitGL(int Width, int Height)
{
  glClearColor(0.0f, 0.0f, 0.0f, 0.0f);	
  glClearDepth(1.0); 
  glDepthFunc(GL_LESS);		
  //glDepthFunc(GL_GREATER);
  glEnable(GL_DEPTH_TEST);		  
}
void DrawGLScene()
{
  glClear(GL_COLOR_BUFFER_BIT |  DEPTH_BUFFER_BIT);		
glLoadIdentity();			
  glTranslatef(-1.5f,0.0f,-6.0f);	    
  /* draw a square (quadrilateral)*/
  glColor3f(0.5f,0.5f,1.0f);			/* set color to a blue shade.*/
  glBegin(GL_QUADS);				/* start drawing a polygon (4 sided)*/
  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 with the polygon*/
 
  /* draw a triangle (in smooth coloring mode)*/
 
  glTranslatef(-1.0f,0.0f,0.0f);	         glBegin(GL_POLYGON);				/* start drawing a polygon */
  glColor3f(1.0f,0.0f,0.0f);			/* Set The Color To Red */
  glVertex3f( 0.0f, 1.0f, -1.0f);		/* Top*/
  glColor3f(0.0f,1.0f,0.0f);			/* Set The Color To Green*/
  glVertex3f( 1.0f,-1.0f, -1.0f);		/* Bottom Right*/
  glColor3f(0.0f,0.0f,1.0f);			/* Set The Color To Blue*/
  glVertex3f(-1.0f,-1.0f, -1.0f);		/* Bottom Left	*/
  glEnd();					  glutSwapBuffers();
 
}

Thanks in advance
RAJESH.R