OT - math question.

[Member 4148]

Originally posted by Imperator Fyron:
Umm... if you are moving it in a random direction, should you not be able to see where it is moving to?

Either way, measure the vector between the start point and the end point. You can get the angles from this vector with pythagorian theorm used a few times. If you have coordinates, no measurement is required, just calculations.

i think he is looking for y position - he has starting point, path traveled (along surface of sphere), distance traveled, wants ending point

[Fyron]

y position is not height. Not sure what I was thinking with arc length, but you definitely need the angles associated with the vector from the starting point to the ending point. The relative height is just the z component of that vector.

Treating the movement as along a circle only works if the only component that is changing is the z component. If x or y change (but not both), then it is no longer a circle, but an ellipse.

[narf poit chez BOOM]

yes, thank you, will try the calculation.

[Fyron]

Actually... if you have the arc length, that gives you the angles you need to calculate the height, as you can calculate the percent of the 360 degress of the circle that that arc takes up using the 2 * pi * radius calculation for circumference.

[narf poit chez BOOM]

no, that part wasn't stated well. i don't have the arc length, only the x distance moved.

[Member 4148]

Originally posted by Imperator Fyron:
y position is not height.

can be - it depends on coordinate system used
there is no particular reason why the center of the sphere has to be the 0 point - he wanted the answer from the bottom of the sphere after all
likewise there is no particular reason why z has to be up, y back, and x right - reducing to circle makes y up using cartesian so it works as height

Originally posted by Imperator Fyron:
Not sure what I was thinking with arc length, but you definitely need the angles associated with the vector from the starting point to the ending point. The relative height is just the z component of that vector.

Treating the movement as along a circle only works if the only component that is changing is the z component. If x or y change (but not both), then it is no longer a circle, but an ellipse.

you forgetting - he constraining himself to move on surface of sphere - any 'straight line' path constrained so makes for a segment of a perfect circle from some perspective - if you choose that perspective, it reduces to a circle just fine
also, narf specified direction of travel - to the right - which pretty much forces a circle sgement anyway

[narf poit chez BOOM]

x is left/right, y is up/down, z is not used.

it's a random straight line x movement and i need the y position on the sphere that a line straight up would hit.

sorry for not being clear the first time. i guess i need to reread mathamatical Posts at least three times.