function SpinningCubeDemo
% SpinningCubeDemo - Demonstrate use of MATLAB-OpenGL toolbox
%
% This demo demonstrates use of OpenGL commands in a Matlab script to
% perform some funky 3D animation in Psychtoolbox.
% It shows a randomly spinning, textured cube. The six sides of the cube
% are textured via binary texture data loaded from a file.
%
% Stop the demo by pressing any key.
%
% Notable implementation details:
% The call InitializeMatlabOpenGL(1) at the top of the script initializes the
% Matlab-OpenGL toolbox and enables the 3D gfx support in Psychtoolbox to
% allow proper interfacing between the OpenGL toolbox and Psychtoolbox.
%
% After this call, all OpenGL functions are made available to Matlab with
% the same - or a very similar - calling syntax as in the C programming
% language. OpenGL constants are made available in C-Style, e.g.,
% GL_DEPTH_TEST, and in a format that is optimized for Matlab, where the
% first underscore is replaced by a dot, e.g., GL.DEPTH_TEST. The former
% style is more convenient if you want to copy & paste OpenGL code written
% in C into a Matlab M-File for use, but it only works if you put all your
% code into one single M-File or function. The second style works in
% subfunctions as well, if you place the commands "global GL" and "global
% GLU" at the top of each function... This inconvenience is unavoidable due
% to the design of Matlab.
%
% In order to execute OpenGL 3D drawing commands to draw 3D stims into a
% Psychtoolbox Onscreen- or offscreen window, one needs to call
% Screen('BeginOpenGL', windowPtr). After OpenGL drawing and before
% execution of standard Screen() commands, one needs to call
% Screen('EndOpenGL', windowPtr) to tell Psychtoolbox that 3D drawing is
% finished.
%
% Some OpenGL functions that return complex parameters to Matlab are not
% yet implemented - this is work in progress. The performance will be also
% lower than when coding in a compiled language like C++ or C -- that's the
% Matlab tax you'll have to pay ;-)
%
% Apart from that, use of OpenGL for Matlab is the same as OpenGL for the C
% programming language. If you are used to OpenGL coding in C, it should be
% a zero effort transition to code in Matlab+PTB. If you don't know OpenGL
% then get yourself one of the many good books or visit one of the many
% OpenGL tutorials on the internet.
%
% The OpenGL Red Book is a great introduction and reference for OpenGL
% programming. Release 1.0 is available online, later releases can be
% purchased in any good book store:
%
% http://www.opengl.org/documentation/red_book_1.0/
%
% For more infos, code samples, tutorials, online documentation, go to:
%
% http://www.opengl.org
%
% The OpenGL for Matlab toolbox was developed and contributed under
% GPL license by Prof. Richard F. Murray, University of York, Canada.
%
% 15-Dec-2005 -- created (RFM)
% 21-Jan-2006 -- Modified for use with OpenGL-Psychtoolbox (MK)
% 16-Feb-2006 -- Modified for use with new MOGL (MK)
% 05-Mar-2006 -- Cleaned up for public consumption (MK)
% 06-Apr-2013 -- Make compatible with OpenGL-ES1.1. (MK)
% Is the script running in OpenGL Psychtoolbox?
AssertOpenGL;
% Find the screen to use for display:
screenid=max(Screen('Screens'));
% Setup Psychtoolbox for OpenGL 3D rendering support and initialize the
% mogl OpenGL for Matlab wrapper:
InitializeMatlabOpenGL(1);
% Open a double-buffered full-screen window on the main displays screen.
[win , winRect] = Screen('OpenWindow', screenid);
% 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, [ .33 .22 .03 1 ]);
glMaterialfv(GL_FRONT_AND_BACK,GL_DIFFUSE, [ .78 .57 .11 1 ]);
glMaterialfv(GL_FRONT_AND_BACK,GL_SHININESS,27.8);
% Enable 2D texture mapping, so the faces of the cube will show some nice
% images:
glEnable(GL_TEXTURE_2D);
% Generate 6 textures and store their handles in vecotr 'texname'
texname=glGenTextures(6);
% Load a binary file which contains binary pixel data for the six textures:
matdemopath = [PsychtoolboxRoot 'PsychDemos/OpenGL4MatlabDemos/mogldemo.mat'];
load(matdemopath, 'face')
% Setup textures for all six sides of cube:
for i=1:6,
% Enable i'th texture by binding it:
glBindTexture(GL_TEXTURE_2D,texname(i));
% Compute image in matlab matrix 'tx'
f=max(min(128*(1+face{i}),255),0);
tx=repmat(flipdim(f,1),[ 1 1 3 ]);
tx=permute(flipdim(uint8(tx),1),[ 3 2 1 ]);
% Assign image in matrix 'tx' to i'th texture:
glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,256,256,0,GL_RGB,GL_UNSIGNED_BYTE,tx);
% Setup texture wrapping behaviour:
glTexParameterfv(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_REPEAT);
glTexParameterfv(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_REPEAT);
% Setup filtering for the textures:
glTexParameterfv(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
glTexParameterfv(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
% Choose texture application function: It shall modulate the light
% reflection properties of the the cubes face:
glTexEnvfv(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_MODULATE);
end
% 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;
% Field of view is 25 degrees from line of sight. Objects closer than
% 0.1 distance units or farther away than 100 distance units get clipped
% away, aspect ratio is adapted to the monitors aspect ratio:
gluPerspective(25,1/ar,0.1,100);
% Setup modelview matrix: This defines the position, orientation and
% looking direction of the virtual camera:
glMatrixMode(GL_MODELVIEW);
glLoadIdentity;
% Cam is located at 3D position (3,3,5), points upright (0,1,0) and fixates
% at the origin (0,0,0) of the worlds coordinate system:
gluLookAt(3,3,5,0,0,0,0,1,0);
% 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,[ 1 2 3 0 ]);
% Emits white (1,1,1,1) diffuse light:
glLightfv(GL_LIGHT0,GL_DIFFUSE, [ 1 1 1 1 ]);
% There's also some white, but weak (R,G,B) = (0.1, 0.1, 0.1)
% ambient light present:
glLightfv(GL_LIGHT0,GL_AMBIENT, [ .1 .1 .1 1 ]);
% Initialize amount and direction of rotation
theta=0;
rotatev=[ 0 0 1 ];
% 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));
% Setup cubes rotation around axis:
glPushMatrix;
glRotatef(theta,rotatev(1),rotatev(2),rotatev(3));
% Clear out the backbuffer: This also cleans the depth-buffer for
% proper occlusion handling:
glClear;
% The subroutine cubeface (see below) draws one side of the cube, so we
% call it six times with different settings:
cubeface([ 4 3 2 1 ],texname(1));
cubeface([ 5 6 7 8 ],texname(2));
cubeface([ 1 2 6 5 ],texname(3));
cubeface([ 3 4 8 7 ],texname(4));
cubeface([ 2 3 7 6 ],texname(5));
cubeface([ 4 1 5 8 ],texname(6));
glPopMatrix;
% Finish OpenGL rendering into PTB window and check for OpenGL errors.
Screen('EndOpenGL', win);
% Show rendered image at next vertical retrace:
Screen('Flip', win);
% Switch to OpenGL rendering again for drawing of next frame:
Screen('BeginOpenGL', win);
% Check for keyboard press and exit, if so:
if KbCheck
break;
end;
end
% Delete all allocated OpenGL textures:
glDeleteTextures(length(texname),texname);
% Shut down OpenGL rendering:
Screen('EndOpenGL', win);
% Close onscreen window and release all other ressources:
sca;
% Well done!
return
% Subroutine for drawing of one face of a textured cube:
% Draw a quadrilateral polygon, defined by indices in vector 'i' and apply
% the texture image 'tx' to it:
function cubeface( i, tx )
% We want to access OpenGL constants. They are defined in the global
% variable GL. GLU constants and AGL constants are also available in the
% variables GLU and AGL...
global GL
% Vector v maps indices to 3D positions of the corners of a face:
v=[ 0 0 0 ; 1 0 0 ; 1 1 0 ; 0 1 0 ; 0 0 1 ; 1 0 1 ; 1 1 1 ; 0 1 1 ]'-0.5;
% Compute surface normal vector. Needed for proper lighting calculation:
n=cross(v(:,i(2))-v(:,i(1)),v(:,i(3))-v(:,i(2)));
% Bind (Select) texture 'tx' for drawing:
glBindTexture(GL.TEXTURE_2D,tx);
% Begin drawing of a new quad:
glBegin(GL.QUADS);
% Assign n as normal vector for this polygons surface normal:
glNormal3f(n(1), n(2), n(3));
% Define vertex 1 by assigning a texture coordinate and a 3D position:
glTexCoord2f(0, 0);
glVertex3f(v(1,i(1)),v(2,i(1)),v(3,i(1)));
% Define vertex 2 by assigning a texture coordinate and a 3D position:
glTexCoord2f(1, 0);
glVertex3f(v(1,i(2)),v(2,i(2)),v(3,i(2)));
% Define vertex 3 by assigning a texture coordinate and a 3D position:
glTexCoord2f(1, 1);
glVertex3f(v(1,i(3)),v(2,i(3)),v(3,i(3)));
% Define vertex 4 by assigning a texture coordinate and a 3D position:
glTexCoord2f(0, 1);
glVertex3f(v(1,i(4)),v(2,i(4)),v(3,i(4)));
% Done with this polygon:
glEnd;
% Return to main function:
return