OpenGL GLuLookAt keep object on screen

[runedog48]

Greetings, I am using a function to render a health bar using quads. However I need to keep the quads on screen, right now it just floats in 3D space. Here is my current code:

void renderHealth(void)
{
    glColor3f(1.0f, 0.0f, 0.0f);
    glBegin(GL_QUADS);
        glVertex3f(0.0f, 0.0f, 0.0);
        glVertex3f((float)getHealth() / 100, 0.0, 0.0);
        glVertex3f((float)getHealth() / 100, 0.3, 0.0);
        glVertex3f(0.0f, 0.3f, 0.0f);
    glEnd();
}

Right now I'm using the GluLookAt function but when I make any move the healthbar stays in place. Can someone make a suggestion on how to fix this?

If you know of a good 2D graphics library that works with OpenGlut please let me know.

[ledow]

GluLookAt surprisingly changes what you are looking at. It doesn't change where it is in space. i.e. it changes the DIRECTION you look in, not what is in that direction.

If your view is already moving through space, then the health bar ALSO has to move in space.

So all you need to do is draw the health bar JUST IN FRONT of wherever the position / view is currently focused. If you know how to draw any object in 3D space, you know how to do this. Just apply a transform to the points of the heatlhbar, to always put it into view.

[runedog48]

GluLookAt surprisingly changes what you are looking at. It doesn't change where it is in space. i.e. it changes the DIRECTION you look in, not what is in that direction.

If your view is already moving through space, then the health bar ALSO has to move in space.

So all you need to do is draw the health bar JUST IN FRONT of wherever the position / view is currently focused. If you know how to draw any object in 3D space, you know how to do this. Just apply a transform to the points of the heatlhbar, to always put it into view.

Thanks, any suggestions on the math? I'm unfortunately horrible at math.