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Tooltip question

Started by fcoutel Nov 30, 2005 at 10:11 PM 2 replies 1.8k views

Original Post

Nov 30, 2005 at 10:11 PM

Hi, In my OGL scene I have some objects and I know their name. What I would like to do is some kind of Tooltip i.e draw a rectangle with the object's name when I hover on it with the mouse. Would someone have some example source code for doing this? Many thanks!

Nairb

145

Nairb

Nov 30, 2005 at 10:21 PM

Determining if you're hovering over the object is the trickiest part. You should be able to do it with "Picking", though. Check out nehe or the redbook - they both have examples of how to do this.

After you've done that, you can simply draw a quad with some text inside it above the object to show the tooltip.

Cheers,
--Brian

fcoutel

Author

fcoutel

Nov 30, 2005 at 10:25 PM

Ok but I need to draw the rectangle in orthographic proj I think? Would you have an example on how to do this?

Thanks!

Ademan555

Dec 1, 2005 at 1:02 AM

just use glOrtho()

Note the part that says "typically the matrix mode is GL_PROJECTION", you probably already know that, but then again it probably didnt hurt to reiterate :-).

so to draw in orthographic mode you want something like:

glMatrixMode(GL_PROJECTION);glPushMatrix();glLoadIdentity();glOrtho(0, 640, 0, 480, -1, 1);//this describes a matrix where the viewport covers a 640 x 480 rectangle//where the upper left hand corner is the point <0,0>//wheras glOrtho(0, 640, 480, 0, -1, 1);//would describle a matrix where the lower left hand corner is the point <0,0>//(note the -1, 1) this affects the depth buffer, i'll assume you know a bit about it//this means that things will be drawn from z=-1 to z=1, but since you're drawing//in 2d anyways chances are z will be 0//Drawing CodeglPopMatrix();

hope that helps
-Dan

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