a disk constantly facing the user

OpenGL OpenGL: Advanced Coding
1

Hi,

Can someone tell me how to rotate the z-axis such that it will always face outward from the screen (toward the human user)? The reason I ask is I want to draw a disk (gluDisk()) that always faces me no matter how I rotate the model. Please help. Thanks.

Tony

2

http://www.gamedev.net/community/forums/topic.asp?topic_id=205092

Flip z with glScale if required.

3

Hi,

Flipping z axis is not what I want. I have a mouse move event handler that rotates the model in response to the mouse moving. However, I want to draw a disk (using gluDisk()) that always faces toward the user from the screen. To draw this disk, I need to do the following. The question is about how to feed parameters to glRotatef(…) below.

glPushMatrix();
glTranslatev(v); // the disk’s location
glRotatef(…)
gluDisk(qobj, 0.0, fRadius, 4, 1);
glPopMatrix();

Thanks.

Tony

4

perhaps
glPushMatrix();
glLoadIdentity(); // reset the modelview matrix
glTranslatev(v); // the disk’s location;
gluDisk(qobj, 0.0, fRadius, 4, 1);
glPopMatrix();

5

Hi,

I tried your way before but it didn’t work. It’s because the disk won’t be in its right position. After glLoadIdentity(), the disk faces you, which is what I want, but its location is at a location without considering the original rotation effect. Maybe I can recaulcate the disk location before glLoadIdentity(). But I don’t know how.

Tony

6

And you’ve posted this in the advanced forum because…?
You can’t possibly, not even for a minute, consider this advanced? Even someone without any prior knowledge of computers couldn’t imagine that making a disk face the viewer could be construde by anyone other than their grandmother as an advanced graphics question…
I’m astounded zed has tried to help you. You should be very grateful.

7

This is not an advanced question, and your identical post was answered in beginners the day before you posted here. If you need additional info in a thread then ask for it, but please don’t repost/crosspost.