Restart speed when mouse clicked

Programming Questions

ecat26

Restart speed when mouse clicked

in Programming Questions • 8 months ago

I am super new to programming. This is what my professor want me to do: Create an animation where a ball is moving inside the display window whose speed gradually slows down. When somebody click the mouse, this ball will be set with a new random speed and move again (will gradually stop again). The ball will bounce if it hits the boundary of the window.

I can't figure out how to get the ball to reset with a new speed.

This is what I have so far:

float x = 50;

float y = 50;

float xspeed = 1.5;

float yspeed = 1;

void setup () {

size (400, 400);

smooth();

noStroke ();

}

void draw () {

x = x + xspeed;

y = y + yspeed;

if ( (x > width-25) || (x < 25) ) {

xspeed = xspeed*(-0.9);

}

if ( (y > height-25) || (y < 25) ) {

yspeed = yspeed*(-0.9);

}

background (255);

ellipseMode (CENTER);

fill (150);

ellipse (x, y, 50, 50);

}

void mouseClicked () {

x = mouseX;

y = mouseY;

xspeed = -xspeed;

yspeed = -yspeed;

}

Any suggestions would be wonderful

Replies(4)

asimes

Re: Restart speed when mouse clicked

8 months ago

I moved a couple of things into setup() because the don't need to be called every frame (I left comments). I noticed that the ellipse() gets stuck, it may happen if xspeed or yspeed is not large enough to get the ball back inside the screen. To solve it I just add or subtract 1.

The answer to your question is using random(). If you give it two numbers, say 0 and 3 like this:

random(0, 3);

It gives you a random number between 0 and 3 including 0 but not 3. This is always positive though, so I doubled the range (0 to 6) and then subtract 3. The new range becomes (about) -3 to 3:

float x = 50;
float y = 50;
float xspeed = 1.5;
float yspeed = 1;
void setup () {
size(400, 400);
smooth();
noStroke();
ellipseMode(CENTER); // Just call this once (not every frame)
/* There is only one object, no need to call this more than once
If you add another object that should have a different color
then you would need this in draw() */
fill(150);
}
void draw () {
x = x + xspeed;
y = y + yspeed;
// I changed this so the ellipse() doesn't get stuck
if (x > width-25) {
x -= 1; // Don't get stuck
xspeed = xspeed*(-0.9);
}
if (x < 25) {
x += 1; // Don't get stuck
xspeed = xspeed*(-0.9);
}
if (y > height-25) {
y -= 1; // Don't get stuck
yspeed = yspeed*(-0.9);
}
if (y < 25) {
y += 1; // Don't get stuck
yspeed = yspeed*(-0.9);
}
background (255);
ellipse(x, y, 50, 50);
}
void mouseClicked () {
x = mouseX;
y = mouseY;
xspeed = random(0, 6)-3; // Random speed between -3 and 3
yspeed = random(0, 6)-3; // Random speed between -3 and 3
}

Edit: Forgot to mention, ellipses() are drawn from the center by default, you actually don't need to specify that.

tfguy44

Re: Restart speed when mouse clicked

8 months ago

Well, you're close.

You have a ball.

The ball is drawn.
The ball moves.

The ball bounces - sometimes.

The ball slows down - but only when it bounces.

You detect when the mouse is clicked.

You adjust the ball's position when the mouse is clicked - but not to a new, random position.

You adjust the ball's speed when the mouse is clicked - but not to a new, random direction.

Hints:
Update the ball's direction before updating it's position.
Adjust the ball's speed each frame - not just when it bounces.
A random point in the frame is ( random(width) , random(height) ).
A random number between 20 and 40 is random(20,40).

asimes

Re: Restart speed when mouse clicked

8 months ago

tfguy44 is giving good advice. The solution I gave is not the only one, it may be worth your while (for learning purposes) to create your own solution to the ellipse() becoming stuck.

When you write:

xspeed = xspeed*(-0.9);

It does two things:

- Reverses the direction

- Slows down the movement

If the ellipse() was moving 1.0 units per frame, and overshoots the right edge by 0.95 units, then the next movement per frame is -0.9 units which means the ellipse() is still off the screen (0.05 units off).

ecat26

Re: Restart speed when mouse clicked

8 months ago

Thank you so much!

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