every demo or link I can find does this a different way with too many code other bits added making it hard to work out. http://www.helixsoft.nl/articles/circle/sincos.htm
so i have been trying to make a SIMPLE needle\Line that responds to a mapped analogRead that's defines the pos. of x1 and y1 on a 128x64 screen.
display.drawLine(64, 64, x1, y1, WHITE);
the closest I have got is
z = map(analogRead(0), 0, 1024, 0, 6);
int x, y; int length = 128; float angle = z;
// calculate x, y from a vector with known length and angle x = length * cos (angle); y = length * sin (angle);
display.drawLine(64, 50, x, y, WHITE);
issue is the needle length is no defined the start and finish points are not defined
but it does move and respond to my POT input smooth and to ratio.
any help will be appreciated. thanks