Getting Current Translation And Rotation In OpenGL

Nick

Sage

Posts: 1,066
Joined: 2004.07

Post: #1

Jul 26, 2006 — 09:34 AM

I'm trying to create some trees procedurally, but I'm having a bit of trouble. It's probably really simple, but I can't seem to find the answer.

Basically, I have a Node class which contains an std::list of Node*s. When I go to draw the nodes, I use the glRotatef and glTranslatef functions to rotate and position the branch correctly. This works fine... for a while. I just added the second generation of branches, but they just come off of the top of my tree (because that's where OpenGL was last told (0, 0, 0) was).

How can I get the current translation and rotation so that I can add that in to my drawing routines? I have almost all of it done, but those two comments in there are what I'm trying to do. I checked with glGet but couldn't find either rotations or translations. What function should I be searching for?

Code:

        glRotatef( mYaw, 0, 1, 0 );

        glRotatef( mPitch, 0, 0, 1 );

        glBegin( GL_LINES );

        glColor3f( mR, mG, mB );

        glVertex3f( 0, 0, 0 );

        glVertex3f( 0, mLength, 0 );

        glEnd();

        glTranslatef( 0, mLength, 0 );

        if ( !mChildren.empty() )

        {

                        //store the current translation and rotation

            std::list< Node* >::iterator itr;

            for ( itr = mChildren.begin(); itr != mChildren.end(); ++itr )

            {

                               //call glLoadIdentity() and restore translation and rotation

                ( *itr )->draw();

            }

        }

unknown

Sage

Posts: 1,403
Joined: 2005.07

Post: #2

Jul 26, 2006 — 10:17 AM

using glGetFloatv but instead you want to just glPushMatrix and glPopMatrix

Sir, e^iÏ€ + 1 = 0, hence God exists; reply!

Nick

Sage

Posts: 1,066
Joined: 2004.07

Post: #3

Jul 26, 2006 — 10:36 AM

Thanks. I'm used to using DirectX and now the Ogre engine, so I'm forgetting things here and there.

kelvin

Member

Posts: 469
Joined: 2002.10

Post: #4

Jul 26, 2006 — 11:16 AM

Don't forget to mind your stack depth.

---Kelvin--
15.4" MacBook Pro revA
1.83GHz/2GB/250GB

Possibly Related Threads...

Thread:		Author	Replies:	Views:	Last Post
	SDL. Current music position	e40pud	0	3,366	Mar 9, 2010 08:46 AM Last Post: e40pud
	OpenGL Center of rotation?	3DTOPO	7	16,051	Sep 26, 2008 01:30 PM Last Post: haegarr
	Retrieving new object coordinates after translation/rotation	chris69m	4	8,773	Apr 13, 2008 06:47 PM Last Post: chris69m
	OpenGl rotation/translation problems?	wyrmmage	2	6,299	Jan 6, 2008 01:58 PM Last Post: wyrmmage
	2D OpenGL With SDL Rotation + Scaling Problem	Greywhind	4	5,518	Jun 2, 2006 04:16 PM Last Post: Greywhind