Drawing multiple letters on the screen efficiently

Programming Help
1

Hi, I’m having some trouble with the function Screen("DrawText"). I’m on Windows 10 with PTB version '3.0.16`.

Basically I need to circular arrange 20 letters on the screen like in the picture:

image
image571×545 2.49 KB

I’ve done it using computing the x and y coordinates (using a custom function) and then drawing all elements with a for loop inside the experiment:

% Screen Setup
    
screen_x_size = 1000;
screen_y_size = 800;
[w1, rect] = Screen('OpenWindow', 0, 0, [0 0 screen_x_size screen_y_size]);

% Experiment

for i = 1:20
    Screen('DrawText',w1, letters(i), circ_pos(i, 1),circ_pos(i, 2), 255);
end
Screen('Flip', w1);

WaitSecs(1);
sca;

Inside my matrix circ_pos I have all my coordinates. However, I’m worried about possible performance issues related to having a for loop each trial of my experiment. Does the Screen("DrawText") function can be used in a vectorized way? I’ve tried to put all my coordinates inside the function but didn’t work.

2

Why are you worried, have you measured that its a problem? Try timing that bit of code and see if there is reason to worry.

3

I’m not expert but I’ve read that vectorized operations are better especially within the experimental routine. Can you suggest me how to check timing issues?

4

put something like
t0 = GetSecs();
before the loop and then
elapsed = GetSecs()-t0; after the loop. will tell you how many seconds it took.