int WIDTH=799;
int HEIGHT=490;
int BLOB_R=5;
float ECOL=0.9;
float EDRAG=0.999;
float EG=0.0;
int N;
int NS;
long CT=0;
int MODE=0;
int ITT=4;

float[] PX = new float[4];
float[] PY = new float[4];
float[] PX_OLD = new float[4];
float[] PY_OLD = new float[4];

int STICKA[] = new int[5];
int STICKB[] = new int[5];
float STICKLENGTH[] = new float[5];


boolean RUNNING=true;

boolean GRAVITY=false;

void setup() {
  size(800, 590, P2D);
  reset();
}

void draw() {

background(0,0,0,0);
noFill();
stroke(255);
rect(0,0,WIDTH,HEIGHT);

renderbuttons();
if(CT++>3000) {reset(); RUNNING=false;} //fuze

if (RUNNING) {
updatepoints();

for (int i=0;i<ITT;i++) {
updatesticks();
constrainpoints();
}

renderpoints();
}


}

void renderpoints() {

  //draw sticks
stroke(255,0,0);
for(int i=0;i<NS;i++) {
line(PX[STICKA[i]],PY[STICKA[i]],PX[STICKB[i]],PY[STICKB[i]]); 
}
  
  //draw points
stroke(164,164,164); 
fill(255,255,0);
for (int i=0;i<N;i++)
{
ellipse(PX[i],PY[i],BLOB_R*2,BLOB_R*2);  
}
  
}

void updatesticks() {
for (int i=0;i<NS;i++) {
  float dx,dy, dist, diff, percent, offx, offy;
  dx=PX[STICKA[i]]-PX[STICKB[i]];
  dy=PY[STICKA[i]]-PY[STICKB[i]];
  dist=sqrt((dx*dx)+(dy*dy));
  diff=STICKLENGTH[i]-dist;
  percent=diff/dist/2;
  offx=dx*percent;
  offy=dy*percent;
  
  PX[STICKB[i]]-=offx;
  PX[STICKA[i]]+=offx;
  PY[STICKB[i]]-=offy;
  PY[STICKA[i]]+=offy;
}
}


void constrainpoints() {
 
 float VX,VY;

for (int i=0;i<N;i++)
{

  
  VX=(PX[i]-PX_OLD[i])*EDRAG;
  VY=(PY[i]-PY_OLD[i])*EDRAG;


if (PX[i]>(WIDTH-BLOB_R)) 
 {
   PX[i]=(WIDTH-BLOB_R);
   PX_OLD[i]=(PX[i]+(VX*ECOL));
 }
 else if (PX[i]<BLOB_R)
  {
    PX[i]=BLOB_R;
    PX_OLD[i]=(PX[i]+(VX*ECOL));
  }
  
  if (PY[i]>(HEIGHT-BLOB_R)) 
 {
   PY[i]=(HEIGHT-BLOB_R);
   PY_OLD[i]=(PY[i]+(VY*ECOL));
 }
 else if (PY[i]<BLOB_R)
  {
    PY[i]=BLOB_R;
    PY_OLD[i]=(PY[i]+(VY*ECOL));
  }
  
} 

}




void updatepoints() {
 
 float VX,VY;

for (int i=0;i<N;i++)
{
 
  VX=(PX[i]-PX_OLD[i])*EDRAG;
  VY=(PY[i]-PY_OLD[i])*EDRAG;
  PX_OLD[i]=PX[i];
  PY_OLD[i]=PY[i];
  PX[i]+=VX;
  PY[i]+=VY;
  PY[i]+=EG;

} 

}

void reset() {


 switch(MODE) {
  case 0: N=2;NS=1;
   twothree();
   STICKA[0]=0;STICKB[0]=1;STICKLENGTH[0]=calclength(0,1);
   break;
  
  case 1: N=3;NS=3;
   twothree();
   STICKA[0]=0;STICKB[0]=1;STICKLENGTH[0]=calclength(0,1);
   STICKA[1]=0;STICKB[1]=2;STICKLENGTH[1]=calclength(0,2);
   STICKA[2]=1;STICKB[2]=2;STICKLENGTH[2]=calclength(1,2);
   break;
  
  case 2: N=4;NS=4;
   four();
   STICKA[0]=0;STICKB[0]=1;STICKLENGTH[0]=calclength(0,1);
   STICKA[1]=0;STICKB[1]=2;STICKLENGTH[1]=calclength(0,2);
   STICKA[2]=1;STICKB[2]=3;STICKLENGTH[2]=calclength(1,3);
   STICKA[3]=2;STICKB[3]=3;STICKLENGTH[3]=calclength(2,3);
   break;
  
  case 3: N=4;NS=5;
   four();
   STICKA[0]=0;STICKB[0]=1;STICKLENGTH[0]=calclength(0,1);
   STICKA[1]=0;STICKB[1]=2;STICKLENGTH[1]=calclength(0,2);
   STICKA[2]=1;STICKB[2]=3;STICKLENGTH[2]=calclength(1,3);
   STICKA[3]=2;STICKB[3]=3;STICKLENGTH[3]=calclength(2,3);
   STICKA[4]=0;STICKB[4]=3;STICKLENGTH[4]=calclength(0,3);
   break;
  } 


RUNNING=false;
CT=0;
}

void twothree() {
float MX,MY, randr, randangle;
MX=random(120,WIDTH-120);
MY=random(120,300);
randr=random(60,100);

PX[0]=coox(MX,MY,randr,0);
PY[0]=cooy(MX,MY,randr,0);
PX_OLD[0]=PX[0]+(random(-150,150)/10);
PY_OLD[0]=PY[0]+(random(-150,150)/10);

PX[1]=coox(MX,MY,randr,500);
PY[1]=cooy(MX,MY,randr,500);
PX_OLD[1]=PX[1]+(random(-50,50)/10);
PY_OLD[1]=PY[1]+(random(-50,50)/10);

randangle=random(100,400);
PX[2]=coox(MX,MY,randr,randangle);
PY[2]=cooy(MX,MY,randr,randangle);
PX_OLD[2]=PX[2]+(random(-50,50)/10);
PY_OLD[2]=PY[2]+(random(-50,50)/10);
}

void four() {
float MX,MY, randr, randangle, opp, leftv, rightv;
MX=random(120,WIDTH-120);
MY=random(120,300);
randr=random(60,100);
opp=random(400,600);
leftv=random(100,opp-100);
rightv=random(opp+100,900);

PX[0]=coox(MX,MY,randr,0);
PY[0]=cooy(MX,MY,randr,0);
PX_OLD[0]=PX[0]+(random(-150,150)/10);
PY_OLD[0]=PY[0]+(random(-150,150)/10);

PX[3]=coox(MX,MY,randr,opp);
PY[3]=cooy(MX,MY,randr,opp);
PX_OLD[3]=PX[3]+(random(-50,50)/10);
PY_OLD[3]=PY[3]+(random(-50,50)/10);

PX[1]=coox(MX,MY,randr,leftv);
PY[1]=cooy(MX,MY,randr,leftv);
PX_OLD[1]=PX[1]+(random(-50,50)/10);
PY_OLD[1]=PY[1]+(random(-50,50)/10);

PX[2]=coox(MX,MY,randr,rightv);
PY[2]=cooy(MX,MY,randr,rightv);
PX_OLD[2]=PX[2]+(random(-50,50)/10);
PY_OLD[2]=PY[2]+(random(-50,50)/10);


}


float calclength(int p1, int p2) {
float dx2,dy2;
dx2=pow(PX[p1]-PX[p2],2);
dy2=pow(PY[p1]-PY[p2],2);
return sqrt(dx2+dy2);
}

void renderbuttons() {
  textSize(16);
  textAlign(CENTER, CENTER);
  stroke(164,164,164);
  String label;
  
  if(RUNNING) {fill(128,110,0); label="RESET";} else {fill(100,100,100); label="Start";}
  rect(0,510,100,30,4);
  fill(255);
  text(label,50,525);
  
  if(GRAVITY) {fill(128,110,0); label="Gravity"; EG=0.5;} else {fill(100,100,100); label="No Gravity"; EG=0.0;}
  rect(110,510,100,30,4);
  fill(255);
  text(label,160,525);
 
 String l;
 for (int i=0;i<=3;i++)
 {

  switch(i) {
  case 0: l="Bar";break;
  case 1: l="Triangle";break;
  case 2: l="Quad";break;
  case 3: l="Braced";break;
  } 
 
  if (i==MODE) {fill(128,110,0);} else {fill(100,100,100);}
  rect(400+(i*90),510,80,30,4);
  fill(255);
  text(l,440+(i*90),525);
 }  
 

  
  //lower buttons
  for (int i=0;i<=3;i++)
 {
  if (i==(ITT-1)) {fill(128,110,0);} else {fill(100,100,100);}
  rect(400+(i*90),550,80,30,4);
  fill(255);
  text(i+1,440+(i*90),565);
 }
 
  textSize(20);
  textAlign(RIGHT, CENTER);
  stroke(164,164,164);
  text("Shape: ",400,525);
  text("Relax Constraints: ",400,565);
}

void mouseClicked() {
 if ( mouseY>=510 && mouseY<=540 && mouseX>0 && mouseX<100) {RUNNING=!RUNNING; if(!RUNNING) {reset();}}
 if ( mouseY>=510 && mouseY<=540 && mouseX>110 && mouseX<210) {GRAVITY=!GRAVITY;}
 if ( mouseY>=510 && mouseY<=540 && mouseX>400 && mouseX<750) {MODE=int((mouseX-400)/90); reset();}
 if ( mouseY>=550 && mouseY<=580 && mouseX>400 && mouseX<750) {ITT=(int((mouseX-400)/90))+1;}
}

float coox(float cx, float cy, float r, float t) {
// calculate x coordinate of point on circle t/1000 of 2PI around
return cx+(r*sin(t*TWO_PI/1000));
}

float cooy(float cx, float cy, float r, float t) {
// calculate x coordinate of point on circle t/1000 of 2PI around
return cy+(r*cos(t*TWO_PI/1000));
}