newDots = bvlExpandContractDots(dots, strDir, delta)
Expansion or contraction of dots in the given direction by the specified amount.
dots - [
Nx2] array of dots to be translated. First column is the x
coordinate, Second Column the y coordinate.
[x1 y1; x2 y2; .... xN yN];
strDir - string specifing the direction
'horiz_out', 'horiz_in', 'vert_out', 'vert_in'
delta - amount to translate
newDots - [
Nx2] translated array
NOTE: Origin is at top-left of screen.
Psychtoolbox/PsychGLImageProcessing/private/bvlExpandContractDots.m