I want to understand more about what I found about all point(s) in a polygon intersecting a bitmap in Android. Say I have a bitmap and I use the getPixels function to retrieve all of my pixel values in that bitmap. Then I draw a polygon of any shape such that part of it intersects with the bitmap. (At any part)
I want then is all of the pixel values of the intersect of the bitmap and the polygon.
Here is an example image of what I am talking about:
The shaded part is the intersection of pixels of the bitmap (larger rectangle) and the closed area of the polygon(smaller rectangle) that I want
From the post about "Point in Polygon" describes using ray casting, a straight line/ray horizontally across the shape, we find how many times the ray intersects the polygon's vertices. I think my solution is an extension of this concept but I am stuck about my approach.
I thought of having multiple rays and somehow grab the number of times that the pixels of the polygon and the pixels of the bitmap intersect but I believe this approach is not practical.
Can someone help with this issue?
Please do not write up a solution as I want to write one on my own although example code and how it works are appreicated as I am a beginner in Android.
