Processing – (Not so) Glitchy Gravity
Posted By: Jordan ParsonsWell I’m trying to wrap my head around vectors in processing because I am not giving up on my flocking simulation and vectors seem to be key to the navigation. So I am following some tutorials by Daniel Shiffman. They are some very nice tutorials and I worked on adapting his gravity tutorial, so that the objects rotate, and move side to side and decelerate when they hit walls. I am having some serious issues with glitching when they settle to the floor and every now an then one goes right through a wall. I can’t really explain it. As always any tips or thoughts are appreciated and welcome. By the way hit space to smack the boids up in the air. http://www.jordanparsons.com/processing/gravity_v1/
Edit:
Thanks to Adam Thomas I made a series of changes to the code, and its much more stable. I also added a holder class so that I can implement the boids with a for loop instead of by hand. The new source is bellow, the old is still avaliable if you check the old app above. Here is the new version.
http://www.jordanparsons.com/processing/gravity_v2/
Gravity:
int bcolors,bcolor,color_ball;
Ball_h ball_h;
void setup(){
smooth();
ellipseMode(CENTER);
size(300,700);
background(100);
ball_h = new Ball_h();
for (int i = 0; i < 4; i++) {
PVector a = new PVector(0,random(.1,.5));
PVector v = new PVector(random(1,8),random(10,25));
PVector l = new PVector(random(1,8),height-random(0,50));
color_ball = int(random(0,255));
ball_h.addBall(new Ball(a,v,l,color_ball));
}
}
void draw(){
background(100);
ball_h.run();
}
void drawVector(PVector v, PVector loc, float scayl) {
pushMatrix();
float arrowsize = 4;
// Translate to location to render vector
translate(loc.x,loc.y);
stroke(0);
// Call vector heading function to get direction (note that pointing up is a heading of 0) and rotate
rotate(v.heading2D());
// Calculate length of vector & scale it to be bigger or smaller if necessary
float len = v.mag()*scayl;
// Draw three lines to make an arrow (draw pointing up since we've rotate to the proper direction)
line(0,0,len,0);
line(len,0,len-arrowsize,+arrowsize/2);
line(len,0,len-arrowsize,-arrowsize/2);
popMatrix();
}
Ball:
class Ball{
PVector loc;
PVector acc;
PVector vel;
PVector flat;
int once, twice, bcolors, bcolor, rotate_on;
float x_loss, y_loss,x_pos,y_pos, turn;
Ball(PVector a, PVector v, PVector l,int bcolors){
acc=a.get();
bcolor=bcolors;
vel=v.get();
loc=l.get();
once=1;
rotate_on=1;
x_loss=.75;
y_loss=2;
PVector flat = new PVector(width/2,height/2);
}
void run(ArrayList balls){
update();
render();
}
void update(){
if(keyPressed) {
if (key == ' '){
vel.y=-10;
rotate_on=1;
if(vel.x==0){
vel.x=6;
acc.y=random(.1,.5);
once=1;
}
}
}
if(loc.x>width){
vel.x*=-1; // change direction
vel.x+=x_loss; // dampen the velocity
loc.x=width; // set location to outside the collision area
}
if(loc.x<0){
vel.x*=-1;
vel.x-=x_loss;
loc.x=1;
}
if(loc.y>height){
vel.y*=-1;
vel.y+=y_loss;
vel.x-=x_loss; // also dampen the x movement a bit
loc.y=height;
// may as well only do this test when you are bouncing on the ground
// remember that your velocities can be negative too!
if(loc.y>height-3){
//println("yes");
//acc.x=0;
// vel.x=0;
//vel.y=0;
if(vel.y<.9 && vel.y>-.9){
if(vel.x<2 && vel.x>-2){
vel.x=0;
vel.y=0;
acc.y=0;
rotate_on=0;
// println("yessssssss");
}
}
}
}
vel.add(acc);
loc.add(vel);
//println(vel.get());
x_pos=loc.x;
y_pos=loc.y;
turn = vel.heading2D();
}
void render(){
ellipseMode(CENTER);
stroke(0);
fill(bcolor,150);
pushMatrix();
translate(loc.x,loc.y);
if(rotate_on==1){
rotate(turn);
}
ellipse(0,0,30,10);
popMatrix();
drawVector(vel,loc,5);
}
}
Balls:
class Ball_h{
ArrayList balls;
Ball_h(){
balls = new ArrayList();
}
void run(){
for(int n=0; n < balls.size(); n++){
Ball b = (Ball) balls.get(n);
b.run(balls);
}
}
void addBall(Ball b){
balls.add(b);
}
}
March 30, 2009 at 2:12 am | 3 Comments »
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March 31, 2009 @ 2:05 am
Hey, found you on #processing.
Had a play with your code. Here are a few of the changes I made to simplify the changes in x velocity
set your x_loss to be between 0 and 1. eg. 0.90
this will set the x velocity to 90% of the old velocity
this dampening should mean that eventually you will match the condition to clamp the velocities and acceleration
if(loc.x>width){ vel.x*=-1; // change direction vel.x*=x_loss; // dampen the velocity loc.x=width; // set location to outside the collision area } if(loc.xheight){ vel.y*=-1; vel.y*=y_loss; vel.x*=x_loss; // also dampen the x movement a bit loc.y=height; // may as well only do this test when you are bouncing on the ground // remember that your velocities can be negative too! if(vel.y-.9){ if(vel.x-.5){ acc.x=0; vel.x=0; vel.y=0; } } }March 31, 2009 @ 2:11 am
arg. silly me! not escaping the < > and it would appear that <code> doesn’t work either. let me try again.
if(loc.x>width){ vel.x*=-1; // change direction vel.x*=x_loss; // dampen the velocity loc.x=width; // set location to outside the collision area } if(loc.x<0){ vel.x*=-1; vel.x*=x_loss; loc.x=(1); } if(loc.y>height){ vel.y*=-1; vel.y*=y_loss; vel.x*=x_loss; // also dampen the x movement a bit loc.y=height; // may as well only do this test when you are bouncing on the ground // remember that your velocities can be negative too! if(vel.y<.9 && vel.y>-.9){ if(vel.x<.5 && vel.x>-.5){ acc.x=0; vel.x=0; vel.y=0; } } }March 31, 2009 @ 8:45 am
Thanks for the edits, I’ll have to try them out after class today and I’ll let you know how it goes.
By the way I use this for syntax highlighting.
<pre class=”brush: java”>
</pre>