Thread: How can I Drag a Point (represented as a Circle) along the Perimeter of a Circle ?

Hello everybody.

I'm trying to solve the following programming exercise:



(Drag points)

Draw a circle with three random points on the circle.

Connect the points to form a triangle.

Display the angles in the triangle.

Use the mouse to drag a point along the perimeter of the circle.

As you drag it, the triangle and angles are
redisplayed dynamically, as shown in Figure.

For computing angles in a triangle, see Listing 4.1.


In order to solve this exercise, I need to solve several "sub-exercise" challenges.

I've already solved the majority of the issues stopping me to solve this problem.


I already know how to draw a circle with three random points on the perimeter of that same circle.


I already know how to connect three points to form a Triangle.

I've created a Triangle class that allows for the creation of two types of Triangles.

One Triangle only receives the length of the three sides.

The second Triangle receives three Points(x, y) and it calculates the sides.


I already know how to Display the angles in the triangle.

The Triangle class has a method to get the angles of the three vertices of the Triangle.


I already know how to Drag a Point Vertice (represented as a Circle) of a Triangle and
after I stop draggging it, the triangle and angles are redisplayed dynamically.


I just don´t know how to drag a Point (represented as a Circle) along the Perimeter of a Circle.

Thank you,

Rogério

Hello Norm.

Thank you for your answer.

I've kept the same approach for moving circles as the previous Thread I've posted in this Forum, in the Java FX Section.

I've created a program to solve a previous programming exercise:



(Geometry: display angles)

Write a program that enables the
user to drag the vertices of a triangle and
displays the angles dynamically as the
triangle shape changes,
as shown in Figure.

The formula to compute angles is given in Listing 4.1.

This program allows the user to click inside any part of the Circle (that is also one vertice of the Triangle) to be dragged, and drag it anywhere.

When the user releases the Button (stops dragging the circle), the Triangle lines are updated and the Triangle Angles are also updated dinamycally.

My problem is not with the drag of the circle, but as to make the dragging "precise".

I need the dragging "precise" so that if I have a Circle with Center (x, y) inside the perimeter of another Circle (Big Circle) before drag, I can only drag that Circle to another position inside the perimeter of the Circle (Big Circle).

Right now I have a sort of "Free Drag", that is, I can Drag one Circle to any position inside the Scene.

Thank you,

Rogério

Hello Norm.

I'm having a problem with the Math necessary to solve this exercise.

I can create the initial "Random" points in the perimeter of the Circle (Big Circle).

I have to use random angles and I can easily place three (or even more) points in the Perimeter of the Big Circle.

I know I'm repeating myself but the problem is to drag the point (circle) and make it appear that is being dragged along the Perimeter of the Big Circle.

I wish you all a good weekend.

Thank you

Rogério

Hello Norm,

Thank you,

Rogério