Vectors with different origins to the same draw panel

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kvent85

Vectors with different origins to the same draw panel

in General Discussion • Other • 4 months ago

Hello guys,

I would like to draw vectors with different origins. How this is possible as in PVector() you can assign only the end of the vector? I used translate() function but changes the origin of all the draw panel.

Replies(5)

janjacobsv

Re: Vectors with different origins to the same draw panel

4 months ago

How are you drawing the vectors? If you are using line() you could use the origin for the first three coordinates, no translations needed.

kvent85

Re: Vectors with different origins to the same draw panel

4 months ago

For example I need a vector starting from (0,0) and end to (100,100) and another from (200,200) to (400,400). Also I need to use the heading() function to calculate the angle of rotation.

janjacobsv

Re: Vectors with different origins to the same draw panel

4 months ago

A vector is either a point in space or a direction, if you want to visualize a vector usually you draw a line. Visualizing vector (0,0) to (100,100) and (200,200) to (400,400) can be done:

line(0,0,100,100);
line(200,200,400,400);

The PVector is just a storage bin to store the x,y,z coordinates of a vector, this you can use for calculating the angle of rotation:

myVector = new PVector(100, 100);
println(myVector.heading());

Should you want the rotation of your (200,200) to (400,400) vector you will first have to substract the two points of your vector to get the direction (400-200, 400-200).

Hope this helps you.

kvent85

Re: Vectors with different origins to the same draw panel

4 months ago

Thanks a lot. I actually have a thought to connect cloud points with vectors in pairs in order to understand if there are a part of a plane by calculate there heading, i.e if the angle is close to 0, is a plane. I did some test but with no luck till now....

janjacobsv

Re: Vectors with different origins to the same draw panel

4 months ago

I dont know exatly what you mean but what i do know is that there is
1 always a plane through three given points
2 always a plane through one point and one vector

Getting that plane using angle between is not the easiest method i think. There are a lot of math websites that show you ways to calculate.

If you mean to find out if two lines are in the same plane you have to check 2 things:
are the lines (vectors) paralel (just normalize them and check if the normalised vectors are the same or inverse)
do the lines intersect, http://processingjs.org/learning/custom/intersect/ a processing script containing that code

if one of these conditions is met then the vectors are in the same plane

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