add postInitDots function

Author: Remi-Gau

src/dot/postInitDots.m

@@ -0,0 +1,26 @@
+function cfg = postInitDots(cfg)
+    %
+    % cfg = postInitDots(cfg)
+    %
+    % generic function to finalize dots set up after psychtoolbox initialization
+    %
+    %
+    % (C) Copyright 2022 CPP_PTB developpers
+
+    cfg.dot.matrixWidth = cfg.screen.winWidth;
+
+    % Convert some values from degrees to pixels
+    cfg.dot = degToPix('size', cfg.dot, cfg);
+    cfg.dot = degToPix('speed', cfg.dot, cfg);
+
+    % Get dot speeds in pixels per frame
+    cfg.dot.speedPixPerFrame = cfg.dot.speedPix / cfg.screen.monitorRefresh;
+
+    cfg.aperture = degToPix('xPos', cfg.aperture, cfg);
+
+    % dots are displayed on a square with a length in visual angle equal to the
+    % field of view
+    cfg.dot.number = round(cfg.dot.density * ...
+                           (cfg.dot.matrixWidth / cfg.screen.ppd)^2);
+
+end