Hi!
I'm new to Processing and tried to make a sketch with a rotating cube. It works but there are strange lines appearing, all going towards one point... I don't understand how I can get rid of them!
Would be nice if you can have a look!
Greetings Powder

int WIDTH, HEIGHT, ANZ_POINTS_1DIM, ANZ_POINTS_GES, DEPTH, ANZ_LINES, anz_lines_straight;
double DELTA, ROT_DELTA, ROT_DELTA_DELTA, rot;
Point pnts[][][];
Line lines[];
Line linesStraight[];

void setup()
{
 frame.removeNotify();
 frame.setUndecorated(true);
 frame.addNotify();
 WIDTH = screen.width;
 HEIGHT = screen.height;
 size(WIDTH, HEIGHT, P3D);
 background(0);
 stroke(255);
 smooth();
 
 // Set up variables
 ANZ_POINTS_1DIM = 4;
 ANZ_LINES = 100;
 DELTA = WIDTH/ANZ_POINTS_1DIM;  //Aenderung
 ANZ_POINTS_GES = ANZ_POINTS_1DIM*ANZ_POINTS_1DIM*ANZ_POINTS_1DIM;
 anz_lines_straight = ANZ_POINTS_GES*2; //Stimmt nicht, nur Testwert
 DEPTH = 100;
 ROT_DELTA = PI/128.0;
 ROT_DELTA_DELTA = 0.1;
 rot = 0;
 
 pnts = new Point[ANZ_POINTS_1DIM][ANZ_POINTS_1DIM][ANZ_POINTS_1DIM];
 lines = new Line[ANZ_LINES];
 
 // Fill Array
 for(int i=0; i<ANZ_POINTS_1DIM; i++)
 {
   for(int j=0; j<ANZ_POINTS_1DIM; j++)
   {
     for(int k=0; k<ANZ_POINTS_1DIM; k++)
     {
       pnts[i][j][k] = new Point(i*DELTA-WIDTH/2, j*DELTA-HEIGHT/2, k*DELTA-DEPTH/2);
     }
   }
 }
 
 //Create Straight Lines
 createStraightLines();
}

void draw()
{
 background(0);
 smooth();
 translate(WIDTH/2, HEIGHT/2, DEPTH/2);
 rotateY((float)rot);
 rotateZ((float)rot*0.5);
 drawAllPnts();
 drawStraightLines();
 rot += ROT_DELTA;
}

void drawAllPnts()
{
 for(int i=0; i<ANZ_POINTS_1DIM; i++)
 {
   for(int j=0; j<ANZ_POINTS_1DIM; j++)
   {
     for(int k=0; k<ANZ_POINTS_1DIM; k++)
     {
       pnts[i][j][k].drawPnt();
     }
   }
 }
}

void createStraightLines()
{
 int curLine = 0;
 for(int i=0; i<ANZ_POINTS_1DIM; i++)
 {
   for(int j=0; j<ANZ_POINTS_1DIM; j++)
   {
     for(int k=0; k<ANZ_POINTS_1DIM; k++)
     {
       checkArraySize(curLine);
       if( pointExistsInArray( i+1, j, k ) )
       {
         Point p1 = new Point( (float)pnts[i][j][k].x, (float)pnts[i][j][k].y, (float)pnts[i][j][k].z);
         Point p2 = new Point( (float)pnts[i+1][j][k].x, (float)pnts[i+1][j][k].y, (float)pnts[i+1][j][k].z);
         lines[curLine] = new Line(p1, p2);
         anz_lines_straight = curLine+1;
         curLine++;          
       }
       if( pointExistsInArray( i, j+1, k ) )
       {  
         lines[curLine] = new Line(new Point( (float)pnts[i][j][k].x, (float)pnts[i][j][k].y, (float)pnts[i][j][k].z ),
                                   new Point( (float)pnts[i][j+1][k].x, (float)pnts[i][j+1][k].y, (float)pnts[i][j+1][k].z ));
         anz_lines_straight = curLine+1;
         curLine++;
       }
       if( pointExistsInArray( i, j, k+1 ) )
       {
         lines[curLine] = new Line(new Point( (float)pnts[i][j][k].x, (float)pnts[i][j][k].y, (float)pnts[i][j][k].z ),
                                   new Point( (float)pnts[i][j][k+1].x, (float)pnts[i][j][k+1].y, (float)pnts[i][j][k+1].z ));
         anz_lines_straight = curLine+1;
         curLine++;
       }  
     }  
   }
 }
}

// Returns new size of array
int checkArraySize(int pos)
{
 if(pos >= (lines.length-1))
   //Double size of Array
   lines = (Line[])expand(lines);
   return lines.length;
}

void drawStraightLines()
{
 stroke( (float)(abs( sin(radians(frameCount)) ) * 225) + 30, 0, 0 );
 for(int i=0; i<anz_lines_straight; i++)
 {
   lines[i].drawLine();
 }
}

boolean pointExistsInArray(int i, int j, int k)
{
 if(i<ANZ_POINTS_1DIM && j<ANZ_POINTS_1DIM && k<ANZ_POINTS_1DIM)
   return true;
 return false;
}

class Point
{
 double x, y, z;
 Point()
 {
   this.x = 0.0;
   this.y = 0.0;
   this.z = 0.0;
 }
 Point(double x, double y, double z)
 {
   this.x = x;
   this.y = y;
   this.z = z;
 }
 void drawPnt()
 {
   point((float)this.x, (float)this.y, (float)this.z);  
 }
}

// Class Line stores 2 3D Points
class Line
{
 Point p1, p2;
 
 Line(Point p1, Point p2)
 {
   this.p1 = p1;
   this.p2 = p2;
 }
 
 void drawLine()
 {
   line((float)p1.x, (float)p1.y, (float)p1.z, (float)p2.x, (float)p2.y, (float)p2.z);
 }
}

Thanks a lot! It works!
But this is strange! Is it a bug?

Any idea what I can do if I want the camera to be inside the cube?

OK thanks! That works really well! For me it doesn't matter if I use P3D or OpenGL!