07-30-2021, 05:06 PM
I say now something about the second plugin Parametric curve (polar). It draws curves given in polar form r=f(t) where t is the argument angle (the angle from the positive x axis).
The default values draw a piece of the logarithmic spiral r=exp(t/10). The default start and end values of t are 0 and 4*pi and with those you get 2 rounds of the spiral.
By changing the inputs you can get shorter or longer parts of the spiral. Inputs r(t)=exp(t/20) and start t = -10*pi and end t = 10*pi give a tighter and longer logarithmic spiral:
I used here the default value "fit in the window" = Yes with a little padding, to get the curve fit nicely on the screen.
As another example, the blue curve on the left below is the cardioid. It was drawn with r(t)=1-cos(t), and the start and end value of t are 0 and 2*pi. Also, the curve is closed, so in the GUI it is good to set "closed" to Yes.
Just to try something else I changed r(t) to (1-cos(t))*sin(t). The result is on the right. I don't know if the curve has any name.
These plugins are now so good and easy that you can go experimenting. It is fun. And even better is the third plugin where the function (and perhaps some other data) is read from a file. I shall explain that in the next post. Tomorrow. But best it is explained in doc.pdf, and there are two examples, so you can already try it yourselves.
The default values draw a piece of the logarithmic spiral r=exp(t/10). The default start and end values of t are 0 and 4*pi and with those you get 2 rounds of the spiral.
By changing the inputs you can get shorter or longer parts of the spiral. Inputs r(t)=exp(t/20) and start t = -10*pi and end t = 10*pi give a tighter and longer logarithmic spiral:
I used here the default value "fit in the window" = Yes with a little padding, to get the curve fit nicely on the screen.
As another example, the blue curve on the left below is the cardioid. It was drawn with r(t)=1-cos(t), and the start and end value of t are 0 and 2*pi. Also, the curve is closed, so in the GUI it is good to set "closed" to Yes.
Just to try something else I changed r(t) to (1-cos(t))*sin(t). The result is on the right. I don't know if the curve has any name.
These plugins are now so good and easy that you can go experimenting. It is fun. And even better is the third plugin where the function (and perhaps some other data) is read from a file. I shall explain that in the next post. Tomorrow. But best it is explained in doc.pdf, and there are two examples, so you can already try it yourselves.