Moving object question - URGENT!

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yanisvaks

Moving object question - URGENT!

in General Discussion • Other • 1 year ago

Hi everyone,

I was trying to create a simple game just to fire a small ball from the gun(straight line) after mouse click but I'm not sure what will work best - update function, loop or array? Could someone help me please?

Thanks.

Replies(2)

tfguy44

Re: Moving object question - URGENT!

1 year ago

I assume you have a Bullet class already that contains everything a bullet needs to know about itself.

I also assume that your Bullet class has a draw() and update() functions, to draw the Bullet and update its position, respectively.

Do you want, or is, there a limit to the number of Bullets on the screen at any time?

YES, ONE: You want a single instance of the Bullet class. draw() will call this Bullet's update() and draw() member functions.
YES, MANY: You want an Array of Bullets. draw() will loop through this Array, calling each Bullet's update() and draw() member functions in turn.
NO, NO LIMIT: You want an ArrayList of Bullets. draw() will loop through this ArrayList, calling each Bullet's update() and draw() member functions in turn.

For additional help, post your current code.

jamesmano..

Re: Moving object question - URGENT!

1 year ago

PVectors are a good way of targeting and animating objects. It will work best with OOP but can be used without.

See, below for a basic example:

http://processing.org/learning/pvector/

here is some code I wrote based on Daniel Shiffman's Zoog character from his Learning Processing book.

class Zoog {
String name;
PVector loc;
PVector vel;
float topSpeed;
float w;
float h;
float s; // scale
float r; // rotation
color c;
color cMouseOver;
color cMouseDown;
Zoog() {
loc = new PVector(width/2, height/2);
vel = new PVector(0,0);
w = 30;
h = 60;
s = 1.0; // scale
topSpeed = 2.0;
c = color(255,0,0);
cMouseOver = c + color(255);
cMouseDown = color(c, 128);
}
Zoog(PVector startLoc) {
this();
loc = startLoc;
}
Zoog(float startX, float startY) {
this(new PVector(startX, startY));
}
Zoog(PVector startLoc, float wVal, float hVal) {
this();
loc = startLoc;
w = wVal;
h = hVal;
}
void setLoc(PVector newLoc) {
loc = newLoc;
}
void setLoc(float newX, float newY) {
setLoc(new PVector(newX, newY));
}
void display() {
ellipseMode(CENTER);
if (within(mouseX, mouseY) && mousePressed) fill(cMouseDown);
else if (within(mouseX, mouseY)) fill(cMouseOver);
else fill(c);
ellipse(loc.x,loc.y, w*s, h*s);
}
void target(PVector targetV) {
// derived from Daniel Shiffman at http://processing.org/learning/pvector/
PVector dir = PVector.sub(targetV,loc); // Find vector pointing towards mouse
dir.normalize(); // Normalize
dir.mult(0.5); // Scale
PVector acceleration = dir; // Set to acceleration
// Motion 101! Velocity changes by acceleration. Location changes by velocity.
vel.add(acceleration);
vel.limit(topSpeed);
}
void calc() {
vel.limit(topSpeed);
loc.add(vel);
}
}

Basically for each time you run through loop, you would call zoog.calc(); then zoog.display();

First you set the target with zoog.target(new PVector(mouseX, mouseY);

Good luck!

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