glRenderMode function always returns 1

Question

0.00/5 (No votes)

See more:

hi all
i'm using OpenGL in vc++
i've drawn a rectnagle, now i want to pick that rectangle and want to change the color of rectangle when i click on that.
for that i've used picking in openGL, but in that the glRenderMode( GL_RENDER ) function always returns 1, even if i click outside the rectangle also.
my code is,

vc++

glSelectBuffer( 50, nSelBuf );
    glGetIntegerv( GL_VIEWPORT, nViewport );
    glRenderMode( GL_SELECT );
glInitNames();
    glPushName( 5 );
	glMatrixMode( GL_PROJECTION );
	glPushMatrix();
	glLoadIdentity();

	gluPickMatrix( CursorDownPos.x, 500 - CursorDownPos.y, PICK_AREA, PICK_AREA, nViewport );
	glMatrixMode( GL_MODELVIEW );
	DrawRect();// this function will draw the rectangle
	glMatrixMode( GL_PROJECTION );
	glPopMatrix();
	int nHits = glRenderMode( GL_RENDER ); // here the nHits value will always be 1.
	glMatrixMode( GL_MODELVIEW );

Posted 2-Jul-12 20:08pm

Jijesh Balakrishnan

Updated 3-Jul-12 18:27pm

v5

Add a Solution

1 solution

Add a Solution

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

Santhosh G_ · Accepted Answer · 2012-07-06T18:47:00

glRenderMode() returns 1 means you clicked on any drawn object.

You should check the values in selection buffer, nSelBuf .
Details of selected objects will be available in selection buffer.

Value of PICK_AREA is 1, right ?.

Please share the entire code. or implementation of DrawRect().

The following link will be helpful to understand picking in opengl.
http://content.gpwiki.org/index.php/OpenGL:Tutorials:Picking[^]

glRenderMode function always returns 1

1 solution

Solution 1

Add your solution here

Preview 0

glRenderMode function always returns 1

1 solution

Solution 1

Add your solution here

Preview 0

Existing Members

...or Join us