Line and rectangle intersection












0














I have a rectangle and a line segment inside the rectangle, and the line can be extended on both sides. I know the coordinates of the rectangle's four vertices as well as the line's two vertices.



I try to write a function that would return the coordinates of the two intersection points of the line segment and the rectangle. The language I am using is python. The problem is that I am not sure which side of the rectangle the line would intersect with. So it makes my function to be extremely complex, and I am not sure if I've covered all the cases or not.



Is there an algorithm for me to do this?










share|improve this question






















  • Is the rectangle axis-aligned?
    – John Anderson
    Nov 22 at 20:38










  • solve it with all four and check the allowed intervals
    – Nimish Bansal
    Nov 22 at 20:38










  • Yes, the rectangle is axis-aligned
    – Yhqjlyr
    Nov 22 at 20:40










  • Do you mean to compute the "possible intersection pts" first for each line, and then check if they are in the legal interval?
    – Yhqjlyr
    Nov 22 at 20:47










  • Write a routine that finds the intersection, if any, of a line segment with a line that contains another segment. Call that routine four times. This reduces the complexity of the code.
    – Rory Daulton
    Nov 22 at 20:48
















0














I have a rectangle and a line segment inside the rectangle, and the line can be extended on both sides. I know the coordinates of the rectangle's four vertices as well as the line's two vertices.



I try to write a function that would return the coordinates of the two intersection points of the line segment and the rectangle. The language I am using is python. The problem is that I am not sure which side of the rectangle the line would intersect with. So it makes my function to be extremely complex, and I am not sure if I've covered all the cases or not.



Is there an algorithm for me to do this?










share|improve this question






















  • Is the rectangle axis-aligned?
    – John Anderson
    Nov 22 at 20:38










  • solve it with all four and check the allowed intervals
    – Nimish Bansal
    Nov 22 at 20:38










  • Yes, the rectangle is axis-aligned
    – Yhqjlyr
    Nov 22 at 20:40










  • Do you mean to compute the "possible intersection pts" first for each line, and then check if they are in the legal interval?
    – Yhqjlyr
    Nov 22 at 20:47










  • Write a routine that finds the intersection, if any, of a line segment with a line that contains another segment. Call that routine four times. This reduces the complexity of the code.
    – Rory Daulton
    Nov 22 at 20:48














0












0








0







I have a rectangle and a line segment inside the rectangle, and the line can be extended on both sides. I know the coordinates of the rectangle's four vertices as well as the line's two vertices.



I try to write a function that would return the coordinates of the two intersection points of the line segment and the rectangle. The language I am using is python. The problem is that I am not sure which side of the rectangle the line would intersect with. So it makes my function to be extremely complex, and I am not sure if I've covered all the cases or not.



Is there an algorithm for me to do this?










share|improve this question













I have a rectangle and a line segment inside the rectangle, and the line can be extended on both sides. I know the coordinates of the rectangle's four vertices as well as the line's two vertices.



I try to write a function that would return the coordinates of the two intersection points of the line segment and the rectangle. The language I am using is python. The problem is that I am not sure which side of the rectangle the line would intersect with. So it makes my function to be extremely complex, and I am not sure if I've covered all the cases or not.



Is there an algorithm for me to do this?







python polygon graph-algorithm intersection line-intersection






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 22 at 20:36









Yhqjlyr

11




11












  • Is the rectangle axis-aligned?
    – John Anderson
    Nov 22 at 20:38










  • solve it with all four and check the allowed intervals
    – Nimish Bansal
    Nov 22 at 20:38










  • Yes, the rectangle is axis-aligned
    – Yhqjlyr
    Nov 22 at 20:40










  • Do you mean to compute the "possible intersection pts" first for each line, and then check if they are in the legal interval?
    – Yhqjlyr
    Nov 22 at 20:47










  • Write a routine that finds the intersection, if any, of a line segment with a line that contains another segment. Call that routine four times. This reduces the complexity of the code.
    – Rory Daulton
    Nov 22 at 20:48


















  • Is the rectangle axis-aligned?
    – John Anderson
    Nov 22 at 20:38










  • solve it with all four and check the allowed intervals
    – Nimish Bansal
    Nov 22 at 20:38










  • Yes, the rectangle is axis-aligned
    – Yhqjlyr
    Nov 22 at 20:40










  • Do you mean to compute the "possible intersection pts" first for each line, and then check if they are in the legal interval?
    – Yhqjlyr
    Nov 22 at 20:47










  • Write a routine that finds the intersection, if any, of a line segment with a line that contains another segment. Call that routine four times. This reduces the complexity of the code.
    – Rory Daulton
    Nov 22 at 20:48
















Is the rectangle axis-aligned?
– John Anderson
Nov 22 at 20:38




Is the rectangle axis-aligned?
– John Anderson
Nov 22 at 20:38












solve it with all four and check the allowed intervals
– Nimish Bansal
Nov 22 at 20:38




solve it with all four and check the allowed intervals
– Nimish Bansal
Nov 22 at 20:38












Yes, the rectangle is axis-aligned
– Yhqjlyr
Nov 22 at 20:40




Yes, the rectangle is axis-aligned
– Yhqjlyr
Nov 22 at 20:40












Do you mean to compute the "possible intersection pts" first for each line, and then check if they are in the legal interval?
– Yhqjlyr
Nov 22 at 20:47




Do you mean to compute the "possible intersection pts" first for each line, and then check if they are in the legal interval?
– Yhqjlyr
Nov 22 at 20:47












Write a routine that finds the intersection, if any, of a line segment with a line that contains another segment. Call that routine four times. This reduces the complexity of the code.
– Rory Daulton
Nov 22 at 20:48




Write a routine that finds the intersection, if any, of a line segment with a line that contains another segment. Call that routine four times. This reduces the complexity of the code.
– Rory Daulton
Nov 22 at 20:48












1 Answer
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Your rectangle can be characterized as xmin, xmax, ymin, and ymax. Find the equation of your line (see this). Then solve your line for each of xmin, xmax, ymin, and ymax.
Eliminate solutions that have x < xmin or x > xmax or y < ymin or y > ymax.






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    1 Answer
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    active

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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    0














    Your rectangle can be characterized as xmin, xmax, ymin, and ymax. Find the equation of your line (see this). Then solve your line for each of xmin, xmax, ymin, and ymax.
    Eliminate solutions that have x < xmin or x > xmax or y < ymin or y > ymax.






    share|improve this answer


























      0














      Your rectangle can be characterized as xmin, xmax, ymin, and ymax. Find the equation of your line (see this). Then solve your line for each of xmin, xmax, ymin, and ymax.
      Eliminate solutions that have x < xmin or x > xmax or y < ymin or y > ymax.






      share|improve this answer
























        0












        0








        0






        Your rectangle can be characterized as xmin, xmax, ymin, and ymax. Find the equation of your line (see this). Then solve your line for each of xmin, xmax, ymin, and ymax.
        Eliminate solutions that have x < xmin or x > xmax or y < ymin or y > ymax.






        share|improve this answer












        Your rectangle can be characterized as xmin, xmax, ymin, and ymax. Find the equation of your line (see this). Then solve your line for each of xmin, xmax, ymin, and ymax.
        Eliminate solutions that have x < xmin or x > xmax or y < ymin or y > ymax.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 22 at 20:57









        John Anderson

        2,3581412




        2,3581412






























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