Find correct corresponding point to extend line
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I tried this at stackoverflow but was told it's more of a geometry problem than programming. So here goes.
I have two non parallel lines(XA and YB) which I need to extend to a curved line piece(PQ). The lines are made of arrays of (x,y) points. A is the last point in XA line and B is the last point in YB line. P and Q are the edge points of the curve.
Now, I need to extend point A to P and point B to Q. Is there a way I can find the correct corresponding point of PQ curve so that A->P and B->Q and not A->Q and B->P, in the latter case the extended lines would intersect, that shouldn't happen.
Previously I had tried a simple boolean, but it was incorrect.
What I tried;
if(abs(A.x() - P.x()) < abs(B.x() - P.x())
// extend A to P
// extend B to Q
else
// extend A to Q
// extend B to P
The above wouldn't work for the image shown below, as then line A would be extended to point Q and line B to P (extension drawn in red).
Any help would be appreciated.
geometry
asked Dec 17 '18 at 11:18
MadzMadz
1225
$endgroup$
add a comment |
$begingroup$
I tried this at stackoverflow but was told it's more of a geometry problem than programming. So here goes.
I have two non parallel lines(XA and YB) which I need to extend to a curved line piece(PQ). The lines are made of arrays of (x,y) points. A is the last point in XA line and B is the last point in YB line. P and Q are the edge points of the curve.
Now, I need to extend point A to P and point B to Q. Is there a way I can find the correct corresponding point of PQ curve so that A->P and B->Q and not A->Q and B->P, in the latter case the extended lines would intersect, that shouldn't happen.
Previously I had tried a simple boolean, but it was incorrect.
What I tried;
if(abs(A.x() - P.x()) < abs(B.x() - P.x())
// extend A to P
// extend B to Q
else
// extend A to Q
// extend B to P
The above wouldn't work for the image shown below, as then line A would be extended to point Q and line B to P (extension drawn in red).
Any help would be appreciated.
geometry
asked Dec 17 '18 at 11:18
MadzMadz
1225
$endgroup$
$begingroup$
Maybe you can try using the y-coordinate instead of the x-coordinate?
$endgroup$
– Math Girl
Dec 17 '18 at 11:26
$begingroup$
That woudn't work either. The Y can vary as well. I think the best solution would be to find if the AP and BQ intesect.. but I'm not sure on how to check that..
$endgroup$
– Madz
Dec 17 '18 at 11:30
$begingroup$
Does my answer below help?
$endgroup$
– Math Girl
Dec 17 '18 at 12:28
add a comment |
$begingroup$
I tried this at stackoverflow but was told it's more of a geometry problem than programming. So here goes.
I have two non parallel lines(XA and YB) which I need to extend to a curved line piece(PQ). The lines are made of arrays of (x,y) points. A is the last point in XA line and B is the last point in YB line. P and Q are the edge points of the curve.
Now, I need to extend point A to P and point B to Q. Is there a way I can find the correct corresponding point of PQ curve so that A->P and B->Q and not A->Q and B->P, in the latter case the extended lines would intersect, that shouldn't happen.
Previously I had tried a simple boolean, but it was incorrect.
What I tried;
if(abs(A.x() - P.x()) < abs(B.x() - P.x())
// extend A to P
// extend B to Q
else
// extend A to Q
// extend B to P
The above wouldn't work for the image shown below, as then line A would be extended to point Q and line B to P (extension drawn in red).
Any help would be appreciated.
geometry
asked Dec 17 '18 at 11:18
MadzMadz
1225
$endgroup$
I tried this at stackoverflow but was told it's more of a geometry problem than programming. So here goes.
I have two non parallel lines(XA and YB) which I need to extend to a curved line piece(PQ). The lines are made of arrays of (x,y) points. A is the last point in XA line and B is the last point in YB line. P and Q are the edge points of the curve.
Now, I need to extend point A to P and point B to Q. Is there a way I can find the correct corresponding point of PQ curve so that A->P and B->Q and not A->Q and B->P, in the latter case the extended lines would intersect, that shouldn't happen.
Previously I had tried a simple boolean, but it was incorrect.
What I tried;
if(abs(A.x() - P.x()) < abs(B.x() - P.x())
// extend A to P
// extend B to Q
else
// extend A to Q
// extend B to P
The above wouldn't work for the image shown below, as then line A would be extended to point Q and line B to P (extension drawn in red).
Any help would be appreciated.
geometry
geometry
asked Dec 17 '18 at 11:18
MadzMadz
1225
asked Dec 17 '18 at 11:18
MadzMadz
1225
asked Dec 17 '18 at 11:18
MadzMadz
1225
asked Dec 17 '18 at 11:18
MadzMadz
1225
asked Dec 17 '18 at 11:18
MadzMadz
1225
1225
$begingroup$
Maybe you can try using the y-coordinate instead of the x-coordinate?
$endgroup$
– Math Girl
Dec 17 '18 at 11:26
$begingroup$
That woudn't work either. The Y can vary as well. I think the best solution would be to find if the AP and BQ intesect.. but I'm not sure on how to check that..
$endgroup$
– Madz
Dec 17 '18 at 11:30
$begingroup$
Does my answer below help?
$endgroup$
– Math Girl
Dec 17 '18 at 12:28
add a comment |
$begingroup$
Maybe you can try using the y-coordinate instead of the x-coordinate?
$endgroup$
– Math Girl
Dec 17 '18 at 11:26
$begingroup$
That woudn't work either. The Y can vary as well. I think the best solution would be to find if the AP and BQ intesect.. but I'm not sure on how to check that..
$endgroup$
– Madz
Dec 17 '18 at 11:30
$begingroup$
Does my answer below help?
$endgroup$
– Math Girl
Dec 17 '18 at 12:28
$begingroup$
Maybe you can try using the y-coordinate instead of the x-coordinate?
$endgroup$
– Math Girl
Dec 17 '18 at 11:26
$begingroup$
Maybe you can try using the y-coordinate instead of the x-coordinate?
$endgroup$
– Math Girl
Dec 17 '18 at 11:26
$begingroup$
That woudn't work either. The Y can vary as well. I think the best solution would be to find if the AP and BQ intesect.. but I'm not sure on how to check that..
$endgroup$
– Madz
Dec 17 '18 at 11:30
$begingroup$
That woudn't work either. The Y can vary as well. I think the best solution would be to find if the AP and BQ intesect.. but I'm not sure on how to check that..
$endgroup$
– Madz
Dec 17 '18 at 11:30
$begingroup$
Does my answer below help?
$endgroup$
– Math Girl
Dec 17 '18 at 12:28
$begingroup$
Does my answer below help?
$endgroup$
– Math Girl
Dec 17 '18 at 12:28
add a comment |
1 Answer
1
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$begingroup$
if(A.y() > B.x())
if(P.y() > Q.y())
// extend A to P
// extend B to Q
else
// extend A to Q
// extend B to P
else
if(P.y() > Q.y())
// extend A to Q
// extend B to P
else
// extend A to P
// extend B to Q
answered Dec 17 '18 at 11:31
Math GirlMath Girl
625318
$endgroup$
add a comment |
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1 Answer
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1 Answer
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$begingroup$
if(A.y() > B.x())
if(P.y() > Q.y())
// extend A to P
// extend B to Q
else
// extend A to Q
// extend B to P
else
if(P.y() > Q.y())
// extend A to Q
// extend B to P
else
// extend A to P
// extend B to Q
answered Dec 17 '18 at 11:31
Math GirlMath Girl
625318
$endgroup$
add a comment |
$begingroup$
if(A.y() > B.x())
if(P.y() > Q.y())
// extend A to P
// extend B to Q
else
// extend A to Q
// extend B to P
else
if(P.y() > Q.y())
// extend A to Q
// extend B to P
else
// extend A to P
// extend B to Q
answered Dec 17 '18 at 11:31
Math GirlMath Girl
625318
$endgroup$
add a comment |
$begingroup$
if(A.y() > B.x())
if(P.y() > Q.y())
// extend A to P
// extend B to Q
else
// extend A to Q
// extend B to P
else
if(P.y() > Q.y())
// extend A to Q
// extend B to P
else
// extend A to P
// extend B to Q
answered Dec 17 '18 at 11:31
Math GirlMath Girl
625318
$endgroup$
if(A.y() > B.x())
if(P.y() > Q.y())
// extend A to P
// extend B to Q
else
// extend A to Q
// extend B to P
else
if(P.y() > Q.y())
// extend A to Q
// extend B to P
else
// extend A to P
// extend B to Q
answered Dec 17 '18 at 11:31
Math GirlMath Girl
625318
answered Dec 17 '18 at 11:31
Math GirlMath Girl
625318
answered Dec 17 '18 at 11:31
Math GirlMath Girl
625318
answered Dec 17 '18 at 11:31
Math GirlMath Girl
625318
625318
add a comment |
add a comment |
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$begingroup$
Maybe you can try using the y-coordinate instead of the x-coordinate?
$endgroup$
– Math Girl
Dec 17 '18 at 11:26
$begingroup$
That woudn't work either. The Y can vary as well. I think the best solution would be to find if the AP and BQ intesect.. but I'm not sure on how to check that..
$endgroup$
– Madz
Dec 17 '18 at 11:30
$begingroup$
Does my answer below help?
$endgroup$
– Math Girl
Dec 17 '18 at 12:28