How can I draw these rectangles in a loop using psychtoolbox... there must be a better way than what I've done. Thanks for your help!!

% Draw base rectangle
r1=[0 0 20 20];

r2=OffsetRect(r1, 200,200);
r3=OffsetRect(r1, 200,235);
r4=OffsetRect(r1, 235,200);
r5=OffsetRect(r1, 235,235);

r6=OffsetRect(r1, 300,235);
r7=OffsetRect(r1, 300,200);
r8=OffsetRect(r1, 335,200);
r9=OffsetRect(r1, 335,235);

r10=OffsetRect(r1, 200,100);
r11=OffsetRect(r1, 200,135);
r12=OffsetRect(r1, 235,100);
r13=OffsetRect(r1, 235,135);

r14=OffsetRect(r1, 300,100);
r15=OffsetRect(r1, 300,135);
r16=OffsetRect(r1, 335,100);
r17=OffsetRect(r1, 335,135);

Screen('FillRect',win, [0, 0, 1], r2);
Screen('FillRect',win, [0, 0, 1], r3);
Screen('FillRect',win, [0, 0, 1], r4);
Screen('FillRect',win, [0, 0, 1], r5);

Screen('FillRect',win, [0, 0, 1], r6);
Screen('FillRect',win, [0, 0, 1], r7);
Screen('FillRect',win, [0, 0, 1], r8);
Screen('FillRect',win, [0, 0, 1], r9);

Screen('FillRect',win, [0, 0, 1], r10);
Screen('FillRect',win, [0, 0, 1], r11);
Screen('FillRect',win, [0, 0, 1], r12);
Screen('FillRect',win, [0, 0, 1], r13);

Screen('FillRect',win, [0, 0, 1], r14);
Screen('FillRect',win, [0, 0, 1], r15);
Screen('FillRect',win, [0, 0, 1], r16);
Screen('FillRect',win, [0, 0, 1], r17);

% Show it on the display:
Screen('Flip', win);

Answer 1

[Jeff Miller]

One simple improvement is to make r a cell array. Add a command at the top like

r=cell(17,1);

Then, instead of commands like

r2=OffsetRect(r1, 200,200);

you would use

r{2}=OffsetRect(r{1}, 200,200);

Then, at the end, you could draw all the rectangles with 3 lines:

for i=2:17
  Screen('FillRect',win, [0, 0, 1], r{i});
end

Screen('flip');

I'm sure you could do even better by working out a pattern to compute the various values of r, 2-17, but I'm not sure that would be worth the effort.

Answer 2

[Olivia Krieger]

Thank you for your help! I would also like to compute a pattern (the computation I'm not worried about, but figuring out how to implement it is where I'm a little stuck.) I will have 64 squares total (which will most often be in the same position), however some boxes will change position. So I think it will be worthwhile for me to implement a pattern (at least for the main pattern).

[Jeff Miller]

There would be be many different ways to do this, and it is tough to say which one will be most convenient without studying your full pattern in detail. But you will probably want to use some kind of loop like this:

for i=2:17
    newx = ???; % compute values here depending on your pattern.
    newy = ???; % You will need 'if' statements if the values depend on i.
    r{i}=OffsetRect(r1, newx,newy);
end

[Olivia Krieger]

Thank you! I will try this