function [] = StereoTeapotDemo(viewMode)

    % StereoTeapotDemo - Demonstrate the combo of OpenGL 3d and PsychToolbox
    % stereo pipeline (anaglyph, LCD shutter, etc.).
    %
    % This is a reprise of the UtahTeapotDemo with stereo vision support. Set
    % viewMode to 1 for LCD shutter glasses, 2-5 for split screen 6-9 for
    % anaglyph
    %
    % 07-May-2007 - Created by Patrick Mineault

    % Is the script running in OpenGL Psychtoolbox?
    AssertOpenGL;

    % Find the screen to use for display:
    screenid=max(Screen('Screens'));

    % Disable Synctests for this simple demo:
    Screen('Preference','SkipSyncTests',1);

    % Setup Psychtoolbox for OpenGL 3D rendering support and initialize the
    % mogl OpenGL for Matlab wrapper:
    global GL;
    InitializeMatlabOpenGL(1);

    if(nargin() < 1)
        viewMode = 9; %Default to red/blue anaglyph
    end

    % Open a double-buffered full-screen window on the main displays screen.
    [win , winRect] = Screen('OpenWindow', screenid, 0, [0 0 1280 1024], 32, 2, viewMode, 0, kPsychNeedFastBackingStore);

    % Setup the OpenGL rendering context of the onscreen window for use by
    % OpenGL wrapper. After this command, all following OpenGL commands will
    % draw into the onscreen window 'win':

    Screen('BeginOpenGL', win);

    % Get the aspect ratio of the screen:
    ar=winRect(4)/winRect(3);

    % Turn on OpenGL local lighting model: The lighting model supported by
    % OpenGL is a local Phong model with Gouraud shading.
    glEnable(GL.LIGHTING);

    % Enable the first local light source GL.LIGHT_0. Each OpenGL
    % implementation is guaranteed to support at least 8 light sources.
    glEnable(GL.LIGHT0);

    % Enable two-sided lighting - Back sides of polygons are lit as well.
    glLightModelfv(GL.LIGHT_MODEL_TWO_SIDE,GL.TRUE);

    % Enable proper occlusion handling via depth tests:
    glEnable(GL.DEPTH_TEST);

    % Define the cubes light reflection properties by setting up reflection
    % coefficients for ambient, diffuse and specular reflection:
    glMaterialfv(GL.FRONT_AND_BACK,GL.AMBIENT, [ 1 1 1 1 ]);
    glMaterialfv(GL.FRONT_AND_BACK,GL.DIFFUSE, [ .78 .57 .11 1 ]);
    glMaterialfv(GL.FRONT_AND_BACK,GL.SPECULAR, [ 1 1 1 1 ]);
    glMaterialfv(GL.FRONT_AND_BACK,GL.SHININESS,128);

    % Set projection matrix: This defines a perspective projection,
    % corresponding to the model of a pin-hole camera - which is a good
    % approximation of the human eye and of standard real world cameras --
    % well, the best aproximation one can do with 3 lines of code ;-)
    glMatrixMode(GL.PROJECTION);
    glLoadIdentity;

    % Setup modelview matrix: This defines the position, orientation and
    % looking direction of the virtual camera:
    glMatrixMode(GL.MODELVIEW);
    glLoadIdentity;

    % Setup position and emission properties of the light source:

    % Set background color to 'black':
    glClearColor(0,0,0,0);

    % Point lightsource at (1,2,3)...
    glLightfv(GL.LIGHT0,GL.POSITION,[ 0 0 -100 0 ]);

    % Emits white (1,1,1,1) diffuse light:
    glLightfv(GL.LIGHT0,GL.DIFFUSE, [ 1 1 1 1 ]);

    % Emits reddish (1,1,1,1) specular light:
    glLightfv(GL.LIGHT0,GL.SPECULAR, [ 1 0 0 1 ]);

    % There's also some blue, but weak (R,G,B) = (0.1, 0.1, 0.1)
    % ambient light present:
    glLightfv(GL.LIGHT0,GL.AMBIENT, [ .1 .1 .6 1 ]);

    %Screen('EndOpenGL', win);

    % Initialize amount and direction of rotation
    theta=0;
    rotatev=[ 0 0 1 ];

    numframes = 1;
    Screen('EndOpenGL', win);
   
    % Animation loop: Run until key press...
    while (1)

        % Calculate rotation angle for next frame:
        theta=mod(theta+0.3,360);
        rotatev=rotatev+0.1*[ sin((pi/180)*theta) sin((pi/180)*2*theta) sin((pi/180)*theta/5) ];
        rotatev=rotatev/sqrt(sum(rotatev.^2));

        RenderScene(0, theta, rotatev, win)
        RenderScene(1, theta, rotatev, win)


        Screen('Flip', win);
        % Check for keyboard press and exit, if so:
        if KbCheck
            break;
        end



        numframes = numframes + 1;
    end


    % Close onscreen window and release all other ressources:
    Screen('CloseAll');

    % Reenable Synctests after this simple demo:
    Screen('Preference','SkipSyncTests',1);

    % Well done!
    %return

%Render the Teapot
function [] = RenderScene(whichEye, theta, rotatev, win)

    global GL;
    %%Render an eye
    Screen('SelectStereoDrawBuffer', win, whichEye);
    Screen('BeginOpenGL', win);
    % Setup cubes rotation around axis:
   
    glMatrixMode(GL.PROJECTION);
    glPushMatrix;
   
    %Appropriate values for each parameter are listed
    %The last parameter is the important one, which defines eye position
    StereoProjection(-6.0, 4.8, 6.0, -4.8, 6.0, -6.0, 0, 10, -0.3+0.6*whichEye);
    glMatrixMode(GL.MODELVIEW);
   
    glPushMatrix;
   
    %rotate us some teapot
    glRotated(theta,rotatev(1),rotatev(2),rotatev(3));

    % Clear out the backbuffer: This also cleans the depth-buffer for
    % proper occlusion handling:
    glClear;
   
    glutSolidTeapot(3   );

    glPopMatrix;
   
    glMatrixMode(GL.PROJECTION);
   
    glPopMatrix;
   
    % Finish OpenGL rendering into PTB window and check for OpenGL errors.
    Screen('EndOpenGL', win);


%Set up the stereo projection matrices. Taken verbatim from Quoc Vuong's
%class Computer Graphics for Vision Research,
%http://www.kyb.mpg.de/bu/people/qvuong/CGV05.html
function [] = StereoProjection(left, top, right, bottom, near, far, zero_plane, dist, eye)

%{
        Perform the perspective projection for one eye's subfield.

    The projection is in the direction of the negative z-axis.

    [default: -6.0, 6.0, -4.8, 4.8]
    left, right, bottom, top = the coordinate range, in the plane of zero parallax setting,
         which will be displayed on the screen.

         The ratio between (right-left) and (top-bottom) should equal the aspect
    ratio of the display.

    [default: 6.0, -6.0]
    near, far = the z-coordinate values of the clipping planes.

    [default: 0.0]
    zero_plane = the z-coordinate of the plane of zero parallax setting.

    [default: 14.5]
    dist = the distance from the center of projection to the plane of zero parallax.

    [default: -0.3]
    eye = half the eye separation; positive for the right eye subfield,
    negative for the left eye subfield.
%}


    dx = right - left;
    dy = top - bottom;

    xmid = (right + left) / 2.0;
    ymid = (top + bottom) / 2.0;

    clip_near = dist + zero_plane - near;
    clip_far  = dist + zero_plane - far;

    n_over_d = clip_near / dist;

    topw = n_over_d * dy / 2.0;
    bottomw = -topw;
    rightw = n_over_d * (dx / 2.0 - eye);
    leftw  = n_over_d *(-dx / 2.0 - eye);

        %// Create a fustrum, and shift it off axis
        %// glTranslate() applies to PROJECTION matrix
    glLoadIdentity();
    glFrustum(leftw,  rightw,  bottomw,  topw, clip_near,  clip_far);
    glTranslatef(-xmid - eye,  -ymid,  -zero_plane -dist);