Android: Find intersection points of a line and an image

Question

Let's say I know two points that make up a line. I want to know the points in which this line goes through a matrix or a drawable of an image (both of which I have access to, so whichever one would be easier to use is welcome). Any ideas on how I can do this?

Are the points in 3D and the matrix in some defined position in 3D? — Ted Hopp, Jun 25 '12 at 17:27
Ah. When you refer to "the points in which this line goes through a matrix", do you mean the pixels that it intersects? Points have zero dimension and pixels have a defined size. — Ted Hopp, Jun 25 '12 at 17:29
good point. the line is actually a vertical line and i know its x coordinate (ie where on the screen the line is positioned) — ElectronAnt, Jun 25 '12 at 17:32

score 0 · Accepted Answer · answered Jun 25 '12 at 17:49

The starting point for you would be a line drawing algorithm. There are many line drawing algorithms. Check the wiki page.

dx = x2 - x1
dy = y2 - y1
for x from x1 to x2 {
        y = y1 + (dy) * (x - x1)/(dx)
        plot(x, y)
}

Given 2 pointsas input to this algorithm, it will plot all the points in-between them. The points can be then mapped to the image in question.

Android: Find intersection points of a line and an image

1 Answers1