Mouse rollover on moving objects

Programming Questions

sorwyn

Mouse rollover on moving objects

in Programming Questions • 9 months ago

I'm playing around with some code and I'm trying to get the orbiting circle to change colour when hovered over. I'm not really sure what I'm doing wrong here.

// Angle of rotation around sun and planets

float theta = 0;

float x,y,w;

boolean mouse;

void setup() {

size(200,200);

smooth();

x = 0;

y = 0;

w = 10;

mouse = false;

}

void draw() {

background(255);

stroke(0);

// Translate to center of window to draw the sun.

//position of rotate origin

translate(width/2,height/2);

fill(255,200,50);

ellipse(0,0,20,20);

// The earth rotates around the sun

pushMatrix();

rotate(theta);

//position relative to sun

translate(50,0);

fill(50,200,255);

ellipse(x,y,w,w);

if (mouse) {

fill(0);

} else {

fill(50,200,255);

}

popMatrix();

theta += 0.001;

}

void rollover(int mx, int my) {

if (mx > x && mx < x + w && my > y && my < y + w) {

mouse = true;

} else {

mouse = false;

}

Replies(6)

asimes

Re: Mouse rollover on moving objects

9 months ago

The main problem is that although transformations like translate() and rotate() draw shapes to different parts of the screen they don't actually affect your x and y variables. If you want to test for hovering then you should position the ellipse by changing its x and y values.

On a side note, the hovering code you have is for testing the area of a square. You can test for the area of a circle by seeing if the mouse is within the radius of a circle using the Pythagorean Theorem.

float theta = 0;
float x, y, w;
void setup() {
size(200, 200);
smooth();
stroke(0);
w = 10;
}
void draw() {
background(255);
fill(255, 200, 50);
ellipse(width/2, height/2, 20, 20);
x = width/2+cos(theta)*50;
y = height/2+sin(theta)*50;
// This actually tests for the mouse being in a square
/*if (mouseX > x-w/2 && mouseX < x+w/2 && mouseY > y-w/2 && mouseY < y+w/2) fill(255, 0, 0);
else fill(50, 200, 255);*/
// Test for a circle using the Pythagorean Theorem
if (sqrt(sq(mouseX-x)+sq(mouseY-y)) < w/2) fill(255, 0, 0);
else fill(50, 200, 255);
ellipse(x, y, w, w);
theta += 0.001;
}

sorwyn

Re: Mouse rollover on moving objects

9 months ago

Thanks. Two more questions: How would I go about staggering the objects? In my original code I could just change the y value in translate. However if I try changing it in the y = height/2+sin(theta)*50; it changes the location of the orbit point. Second question, to add a mousePressed function would I add an if statement like this?

if (sqrt(sq(mouseX-x)+sq(mouseY-y)) < w/2) {
if (mousePressed) {
rect(x,y,50,10);
}
fill(255, 0, 0);
} else {
fill(50, 200, 255);
}

asimes

Re: Mouse rollover on moving objects

9 months ago

If by stagger you mean make them orbit at a larger / shorter distance from the central ellipse then just make the *50 bigger / smaller.

I don't understand what you want to do with the rect(). If you want something to happen while the mouse is pressed that is fine, if you want something to happen once when the mouse is pressed use this: http://processing.org/reference/mousePressed_.html

sorwyn

Re: Mouse rollover on moving objects

9 months ago

By stagger I mean if they had the same x position but different locations around the central ellipse so that they're not rotating on each other. Right now if I change the *50 it changes the distance from which the circle orbits. How would I have the objects orbit at the same distance but stagger them so that they are not over top of each other when they are moving? I hope this is clearer.

I also figured out what I wanted the rect() thing to do.

PhiLho

Re: Mouse rollover on moving objects

9 months ago

You just need a different theta value for each object.

asimes

Re: Mouse rollover on moving objects

9 months ago

I think you mean change the center of rotation? If you want them to have the same x then leave that part alone but change y's center of rotation value. For example:

y = 100+sin(theta)*50;

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