Gardner Lab

Stanford University

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Table of Contents

Main screen functions

mglOpen: Opens the screen

usage: mglOpen(whichScreen, <screenWidth>, <screenHeight>, <frameRate>, <bitDepth>)
purpose: Opens an openGL window

argument value
whichScreen 0=Window, 1=primary screen, 2=secondary screen, etc
<screenWidth> [width] in pixels
<screenHeight> [height] in pixels
<frameRate> [frameRate] in hertz
<bitDepth> [bitDepth] this is usually 32 bits

Open last monitor in list with current window settings 

mglOpen

Open with resolution 800×600 60Hz 32bit fullscreen 

mglOpen(1,800,600,60,32);

Open in a window 

mglOpen(0);


Note that mglOpen hides the mouse cursor as a default. If you want to show the mouse cursor, you should call mglDisplayCursor after opening the screen.

mglFlush: Flips front and back buffer

purpose: swap front and back buffer (waits for one frame tick)
usage: mglFlush
N.B. mglFlush has to be called after each operation that involves drawing or erasing from the currently open window

mglClose: Closes the screen

purpose: close OpenGL screen
usage: mglClose

Other screen functions

mglResolution: Get and set display resolution

availability: mgl 2.0
usage: mglResolution(<whichScreen>, <screenWidth>, <screenHeight>, <frameRate>, <bitDepth>)
purpose: Gets or sets the resolution of a display usage: To get the resolution of the default display:

mglResolution

To get the resolution of display 1:

mglResolution(1)

To set the resolution of display 2 to 1440×900:

mglResolution(2,1440,900)

mglSwitchDisplay: Switch between multiple monitors

usage: mglSwitchDisplay(<displayID>)
purpose: If you are using multiple monitors to display stimuli (like for a dichoptic presentation), you can open up multiple displays using this function.

argument value
<displayID> which display to switch to

You can use this to open up two separate screens and control them independently. For example, say you have two monitors 1 and 2. You open the first in the usual way: 

mglOpen(1)

Then you switch monitors so that you can open up the other one 

mglSwitchDisplay
mglOpen(2)

Now if you want draw to the first display, you can do 

mglSwitchDisplay(1)
mglClearScreen(0.5);
mglFlush;

Similarly, to draw to the second display 

mglSwitchDisplay(2);
mglClearScreen(1);
mglFlush;

You can check the status of all open displays with: 

mglSwitchDisplay(-2);

If you want to close all displays at once, you can do: 

mglSwitchDisplay(-1);

mglMoveWindow: Moves windows created by mglOpen(0)

usage: mglMoveWindow(leftPos,topPos)
purpose: Moves a window created by mglOpen(0)

argument value
leftPos Left position of where the window will be moved to
topPos Top position of where the window will be moved to 
mglOpen(0);
mglMoveWindow(100,100);


mglDescribeDisplays: Get information about your monitor and computer system

usage: [displayInfo computerInfo] = mglDescribeDisplays()
purpose: Gets information about your displays (as an array of structs with values for each monitor). As well as a single struct with info about your computer.

mglFrameGrab: Frame grab to a matlab matrix

usage: mglFrameGrab(<frameRect>)
purpose: Does a frame grab of the current mgl screen and returns it as a matrix of dimensions widthxheightx3

argument value
frameRect Optional argument that is a 1×4 array specifying a rectangular part of the frame to grab in the format [x y width height] 
mglOpen();
mglScreenCoordinates;
mglClearScreen([0 0 0]);
mglPoints2(mglGetParam('screenWidth')*rand(5000,1),mglGetParam('screenHeight')*rand(5000,1));
mglPolygon([0 0 mglGetParam('screenWidth') mglGetParam('screenWidth')],[mglGetParam('screenHeight')/3 mglGetParam('screenHeight')*2/3 mglGetParam('screenHeight')*2/3 mglGetParam('screenHeight')/3],0);
mglTextSet('Helvetica',32,[1 1 1]);
mglTextDraw('Frame Grab',[mglGetParam('screenWidth')/2 mglGetParam('screenHeight')/2]);
frame = mglFrameGrab;
imagesc(mean(frame,3)');colormap('gray')
mglFlush

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