It’s not clear what you want. And I think you don’t need an extension for that, it’s just a calculation.
I can give you the distance in pixels between two points with this:
The list of pixels in between two points can be obtained by using 2 FOR loops, one for the x and another for the y increments until the point is reached. Is not going to be fast if the distance is long, so if it’s made in an extension, it would be better, but is not impossible to make with blocks.
You can’t print the list of coordinates of points at distance 3 because the coordinates increase in both x-component and y-component.
But I have another idea. You can calculate the equation of the straight line and check individually for each coordinate. But you know there are millions of coordinates. Therefore its not possible.
Uhm… Your post says basically the same thing I said. Try to add information to the discussions, not repeat what others say just to count more comments towards your badges.