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I'm drawing 4 rectangles with randomized rotations. They seem randomized in terms of their angels, however I need them to be a little bit different. The rectangles should not be close to each other, they all should be at least 10 degrees apart. And this also should be randomized. How can I define this? Thank you!

rot_angle1=randi(360); 
rot_angle2=randi(360); 
rot_angle3=randi(360); 
rot_angle4=randi(360); 
rect_array=255*ones(1,1);
t1=Screen('MakeTexture',w,rect_array);
t2=Screen('MakeTexture',w,rect_array);
t3=Screen('MakeTexture',w,rect_array);
t4=Screen('MakeTexture',w,rect_array);
t5=Screen('MakeTexture',w,rect_array);

destrect(1,:) = (ul_c + stim_array);
destrect(2,:) = (ur_c + stim_array);
destrect(3,:) = (ll_c + stim_array);
destrect(4,:) = (lr_c + stim_array);

Screen('DrawTexture',w,t2,[],destrect(1,:),rot_angle1);
Screen('DrawTexture',w,t3,[],destrect(2,:),rot_angle2);
Screen('DrawTexture',w,t4,[],destrect(3,:),rot_angle3);
Screen('DrawTexture',w,t5,[],destrect(4,:),rot_angle4);
Screen('Flip',w);
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up vote 0 down vote accepted

instead of rot_angle1=randi(360); lines, define 

rot_angle=randi(36,1,4)*10;

Now there is at least 10 deg apart in each angle, with step size of 10 degrees. Note that this doesn't mean the angles will be unique. using randi there's a chance two rotation angles will be the same. In order to impose uniquness use 

rot_angle=randperm(36)*10;

Use rot_angle(1) instead of rot_angle1 etc.

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Great! Thank you! – Felis Jun 7 '13 at 21:17
    
Felis, see my edit regarding how to impose uniqueness of random angles... – bla Jun 7 '13 at 22:07
    
I tried that. Still they are not always unique. Also, can you explain the reason for 35? I don't get it. Thanks. – Felis Jun 7 '13 at 23:48
    
when I wrote unique I meant non-repeating. randperm assures that the random numbers you'll get are non repeating because it just scrambles all the numbers from one to N. The reason for 35 is a bug it should actually be 36. then you generate a random number from the set (10,20,30...360) – bla Jun 8 '13 at 0:38
    
Ok got it. thank you. – Felis Jun 8 '13 at 1:02

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