Psychtoolbox/ Draw four rectangles.

 PsychDefaultSetup(2);
 +Screen('Preference', 'SkipSyncTests', 1);
 +
 +screens = Screen('Screens');
 +screenNumber = max(screens);
 +
 +white = WhiteIndex(screenNumber);
 +black = BlackIndex(screenNumber);
 +
 +[wPtr, rect] = PsychImaging('OpenWindow', screenNumber, black);
 +
 +[screenXpixels, screenYpixels] = Screen('WindowSize', wPtr);
 +[xCenter, yCenter] = RectCenter(rect);
 +
 +baseRect = [0 0 100 100];
 +
 +squareXpos = [screenXpixels * 0.15 screenXpixels * 0.25 screenXpixels * 0.35 screenXpixels * 0.45];
 +squareYpos = [screenYpixels * 0.15 screenYpixels * 0.25 screenYpixels * 0.35 screenYpixels * 0.45];
 +numSquares = length(squareXpos);
 +
 +allColors = [1 0 0; 0 1 0; 0 0 1; 1 0 0];
 +
 +
 +allRects = nan(4, 4);
 +for i = 1:numSquares
 +    allRects(:, i) = CenterRectOnPointd(baseRect, squareXpos(i), squareYpos(i));
 +     
 +end
 +
 +Screen('FillRect', wPtr, allColors, allRects);
 +Screen('Flip', wPtr);
 +
 +KbWait;
 +sca;

I'd like to draw four rectangles. But there is a error like "Screen('FillRect', windowPtr [,color] [,rect] )" . I don't know why this code has a error... Please, help me...!

Answer 1

[Mikel Jimenez]

Hi,

I think you need to provide allColors and allRects as column vectors:

"Instead of filling one rectangle, you can also specify a list of multiple rectangles to be filled - this is much faster when you need to draw many rectangles per frame. To fill n rectangles, provide “rect” as a 4 rows by n columns matrix, each column specifying one rectangle, e.g., rect(1,5)=left border of 5th rectange, rect(2,5)=top border of 5th rectangle, rect(3,5)=right border of 5th rectangle, rect(4,5)=bottom border of 5th rectangle. If the rectangles should have different colors, then provide “color” as a 3 or 4 row by n column matrix, the i’th column specifiying the color of the i’th rectangle."

Not sure if you are doing it this way, yet I guess you have sorted this out by now.

Best,

Mikel