问题
For my application, i need to divide diagonally the screen of my iphone in 4 parts and detect which of the part was touched. I am very confused because my areas are triangles and not squares and I can't find a solution to detect which of the triangle was touched...
I get the touched Point with method touchesBegan, and there I'm stuck... :( How to define triangle shapes and test if it was touched? with View? layer?
It could be really cool if someone could help me.
回答1:
This website show some algorithms to check if a point is inside a triangle or not.
http://www.blackpawn.com/texts/pointinpoly/default.html
Depending on how fast your application should run, you might want to precompute and store a matrix will all possible x and y coordinates. This matrix would look something like this:
point_inside[X][Y][triangle]
Where X and Y are the coordinates in your screen and "triangle" is pointer to which triangle should be in that point.
回答2:
Given width, height of the rectangle and x, y of a point in the rectangle you can do this...
int s = y * width / height;
int code = (x > s) + 2*(x > width - s);
code will be a number from 0 to 3 representing which part has been selected.
来源：https://stackoverflow.com/questions/3001487/how-to-detect-touch-in-triangle-area