MousePressed In Specific spot

Programming Questions

benlen

MousePressed In Specific spot

in Programming Questions • 9 months ago

Hey folks. I'm doing a rollover and when I click within my sketch, the line changes from black to red. However, I want my mousePressed command only to change the color of the line when I click the line itself. How do I do that. Do I use an "if" function?

here's my code:

void setup() {
size(240,120);
smooth();
strokeWeight(0);
}

void draw(){
background(#FFFFFF);
stroke(102);
if (mousePressed){
stroke(#C00000);
}else{
}
line(0,0,50,50);
}

Replies(6)

tgptialves

Re: MousePressed In Specific spot

9 months ago

It's not easy, but it's not difficult:

You need to calculate the line equation:

-> y = m*x + b

->m=(y2-y1)/(x2-x1)

->b=y1-m*x1 or b=y2-m*x2

-> once you have this, you just have to do this: if(mouseY==m*mouseX+b) then mouse is on the line.

NOTES: When calculating m, you may come to a indertermination, because x2 might be equal to x1 making m equal to infinite. In that case you just need check if mouseX is equal to x2 or equal to x1.

benlen

Re: MousePressed In Specific spot

9 months ago

Thank you for your reply. I'm completely new to processing so when you say "calculate" I imagine it'll make sense to me as I continue in my studies (doing Processing for a graduate school intro class, it's not exactly my forte) but I have another question:

Would it be easier if instead of making this a mousePressed, it was a rollover instead? As in, if I roll the mouse over the line and it changed color, would that be easier for a newbie to code?

Thank you so much!

tgptialves

Re: Re: MousePressed In Specific spot

9 months ago

No, it would be the same, since you have to check if the mouse touched the line.

It's not that difficult to code that, in fact it's something that can be done in less than 5 minutes and I already gave you almost anything for it to be done, but I know it's not a easy thing to do when you're new to programming, but I might do that to you later.

tgptialves

Re: MousePressed In Specific spot

9 months ago

Here you go:

Point[] line = new Point[2];
public void setup()
{
line[0]=new Point(20, 30);
line[1]=new Point (70, 30);
size(300, 300);
}
public void draw()
{
background(255);
if(touchedLine())
stroke(255, 0, 0);
else
stroke(0);
line(line[0].x, line[0].y, line[1].x, line[1].y);
}
public boolean touchedLine()
{
if(line[0].x==line[1].x)
if(mouseX==line[0].x)
return true;
else
return false;
double m, b;
m=(double)(line[1].y-line[0].y)/(double)(line[1].x-line[0].x);
b=(double)line[1].y-m*(double)line[1].x;
System.out.println("Rato: "+mouseY);
System.out.println("Recta: "+(m*mouseX+b));
if(mouseY==(int)(m*mouseX+b))
return true;
return false;
}

GoToLoop

Re: MousePressed In Specific spot

9 months ago

There's a similar concept example in this post:
topic/decisions-if-and-co

Take a peek there!

benlen

Re: MousePressed In Specific spot

9 months ago

Thank you both for your help! I am brand new to programming with Processing and taking it for a class, so I can understand my lack of understanding must be frustrating. Again, thank you for answering, I figure as I learn more about this program I'll gradually become more capable! Thank you!

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