Slow down object's speed

Processing Beginners
1

Hello! I’m a bit stuck with my conditional statement for this basic program I’m working on. Two objects at different y coordinates start moving towards the width of the screen at varying speeds. When they approach each other at a specific distance, both objects need to slow down and once they get past that distance, their original speed also returns.
Here’s the function I created to compute the distance between the objects and adjust the speed accordingly:

void closingDist(Bubble other) { 
    float d = dist(xpos, 0, other.xpos, 0); //declared a float d which computes the distance between the xpos of the two objects
    if (d <= 4) { //made a conditional statement dependent on the value of d
      xspeed--; //if d<=4 (ie if the objects are within 4 pixels horizontally), speed will slow down
      //having a problem since both bubbles start of at the place and the bubble just starts going backwards or just maintains that speed 
      stroke(255, 0, 0);
      line(xpos, ypos, other.xpos, other.ypos); 
    } 
  }

I also tried multiplying the speed by a percentage but it never returns to the original speed even when the distance is more than 4 pixels. I believe my condition works since the part of the code that connects the two bubbles when in the same range works but I’m just stuck with how I can adjust the speed.
Any clarifications would be greatly appreciated.

2

Okay… I don’t get it. If 2 objects are at different y coordinates then why are you calculating the distance like this?

Instead you should calculate the distance like this
float d = dist(xpos, ypos, other.xpos, other.ypos);

3

Oh sorry! I didn’t think it was necessary at first because I thought I only need to compute the distance between the x coordinates so I set it to 0. Noob mistake.

4

I think that’s okay, you can use 0 instead of y when you’re just interested in x

The problem might be elsewhere

5

Do you have a code line that says speed=4; ? It’s not in the code section you posted.

Also 4 pixels is a very small amount. When your xspeed is 4 then this distance might never occur

1 Like
6

Hello @akira,
Could adding an else - statement to the function to switch back to the original speed be a possible solution?
:nerd_face:

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7

Not in the class code! However, it’s part of the arguments for my constructor which looks like this:

Bubble(color tempC, float tempXpos, float tempYpos, float tempXspeed) {
    c = tempC;
    xpos = tempXpos;
    ypos = tempYpos;
    xspeed = tempXspeed;
  }

Unfortunately, the instructions for the project require that the objects must slow down once they’re within 4 pixels of each other so I don’t really know how I should work around that.

Apologies if I used the wrong terms–I’m still familiarizing myself with the concepts!

8

Thank you for your reply! I tried doing that but I don’t know how I can return the original value when it uses a value that was put in my main line of code (this function was written in my class). xspeed = xspeed as an else - statement, for example, shows the error that it has no effect. I’ve written in a previous reply the arguments for the constructor that I made if that helps.

9

To have this in your constructor won’t help, since it is called only once and not throughout. You need to repeat this line, eg in an else-part of your if-clause

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10

Ah!! I had a feeling my suggestion was probably missing something… :slight_smile:

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11

@debxyz : I had just overlooked yours - was on my phone

I am sorry!!

12

It’s alright!! I tried doing your earlier advice about changing the condition from 4 since it’s too small to actually see the difference and you’re right! I also added a new variable that replaces xspeed (slows it down to half its value). Thank you so much for helping me!

1 Like