switching projection modes

Member

Posts: 45
Joined: 2002.04

Post: #1

Aug 10, 2003 — 08:03 PM

ok, so I have a menu system setup when my game initially starts, and from that I want to change over to my game view.

My menus use a 2D view (gluOrtho2D) and I want to switch to a perspective view for my game... (gluPerspective).

I am using GLUT, so I have entirely separate callbacks for each, menus and game..

all I get is a black screen when I switch over..

this is my setup:

Code:

glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    gluPerspective(45, 4.0 / 3.0, 1, 1000);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

    gluLookAt(0.0, 5.0, -5.0,  0.0, 0.0, 0.0,  0.0, 1.0, 0.0);

my draw callback function looks like this:

Code:

    glClear(GL_COLOR_BUFFER_BIT);

    render_xz_plane();

    glColor3f(1.0,1.0,1.0);

    glBegin(GL_QUADS);

    {

        glVertex3f(0.0, 0.0, 0.0);

        glVertex3f(10.0, 0.0, 0.0);

        glVertex3f(10.0, 0.0, 10.0);

        glVertex3f(0.0, 0.0, 10.0);

    }

    glEnd();

    glPushMatrix();

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    gluOrtho2D(0.0, game_settings.width, game_settings.height, 0.0);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

    draw_fps((float)game_settings.width - 250, 20.0);

    //the follow quad is just to test... and it doesn't work..

    glColor3f(1.0,0.0,0.0);

    glBegin(GL_QUADS);

    {

        glVertex2f(0.0, 0.0);

        glVertex2f(10.0, 0.0);

        glVertex2f(10.0, 10.0);

        glVertex2f(0.0, 10.0);

    }

    glEnd();

    glPopMatrix();

    glutSwapBuffers();

I have no idea what is going on..
I just get a black screen..

I was under the impression that one was able to combine different views together.. to achieve different effects...

I want to do all my UI graphics in a 2D space and overlay them on my 3D scene..

how>?

Hank-

/* Drunk...... fix later.... */

OneSadCookie

Luminary

Posts: 5,125
Joined: 2002.04

Post: #2

Aug 10, 2003 — 08:34 PM

You're only pushing and popping the MODELVIEW matrix, not the PROJECTION matrix. You should be pushing and popping both.

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