Psychtoolbox>Screen.{mex*} subfunction

Quickly draw an array of dots. “xy” is a two-row vector containing the x and y
coordinates of the dot centers, relative to “center” (default center is [0 0]).
“size” is the diameter of each dot in pixels (default is 1). Instead of a common
size for all dots you can also provide a vector which defines a different dot
size for each dot. Different graphics cards do have different limits on the
maximum size of dots, 10 or 63 are typical limits.
“color” is the the clut index (scalar or [r g b a] vector) that you want to poke
into each dot pixel (default is black). Instead of a single “color” you can
also provide a 3 or 4 row vector,which specifies an individual RGB or RGBA color
for each corresponding point.
“dot_type” is a flag that determines what type of dot is drawn: 0 (default) and
4 draw square dots, whereas 1, 2 and 3 draw round dots (circles) with
anti-aliasing: 1 favors performance, 2 tries to use high-quality anti-aliasing,
if supported by your hardware. 3 Uses a builtin shader-based implementation.
dot_type 1 and 2 may not be supported by all graphics cards and drivers. On some
systems Screen() will then automatically switch to dot_type 3 - our own
implementation - in such a case. If you use round dot_type 1, 2 or 3 you’ll also
need to set a proper blending mode with the Screen(‘BlendFunction’) command,
e.g., GL_SRC_ALPHA + GL_ONE_MINUS_SRC_ALPHA. A dot_type of 4 will draw square
dots like dot_type 0, but may be faster when drawing lots of dots of different
sizes by use of an efficient shader based path.
“lenient” If set to 1, will not check the sizes of dots for validity, so you can
try requesting sizes bigger than what the hardware claims to support.

The optional return arguments [minSmoothPointSize, maxSmoothPointSize,
minAliasedPointSize, maxAliasedPointSize] allow you to query the minimum and
maximum allowed ‘size’ for smooth anti-aliased dots (dot_type 1,2,3) and for non
anti-aliased square dots (dot_type 0 and 4). Calling […] = Screen(‘DrawDots’,
windowPtr) will only query these point size limits without drawing any dots.

###See also: BlendFunction