/*  Prinzip : Turtle von LOGO, aber in 3D.  
Daher hat die Turtle nicht nur x und y,
sondern auch z-Position und nicht nur einen
Winkel, sondern zwei.
*/
float TurtleX;             /*   Turtledaten */
float  TurtleY;
float  TurtleZ;
int WinkelVertikal;
int WinkelHorizontal;
color  TurtleColor;
boolean StiftHoch =  false;
// Ende Turtledaten
/* =====================    Inits   &   TOOLS            ================================ */
void setup() {
 size ( screen.width, screen.height, P3D );  
 TurtleColor = color(255, 0, 0 );  
 color ( TurtleColor);    
 background(110);
 TurtleX = width / 2;
 TurtleY = height / 2;
 TurtleZ = 10;
 WinkelVertikal = 0 ;
 WinkelHorizontal = 0 ;
 smooth();
}
void CheckWinkel()
{
 // Bereichsüberprüfung
 if (WinkelHorizontal > 359) {
   WinkelHorizontal  = WinkelHorizontal  - 360;
 }
 if (WinkelHorizontal > 359) {
   WinkelHorizontal  = WinkelHorizontal  - 360;
 }
 if (WinkelHorizontal > 359) {
   WinkelHorizontal  = WinkelHorizontal  - 360;
 }
 if (WinkelVertikal > 359) {
   WinkelVertikal = WinkelVertikal - 360;
 }
 if (WinkelVertikal > 359) {
   WinkelVertikal = WinkelVertikal - 360;
 }
 if (WinkelVertikal > 359) {
   WinkelVertikal = WinkelVertikal - 360;
 }
 if (WinkelHorizontal < 0) {
   WinkelHorizontal = 360 + WinkelHorizontal;
 }
 if (WinkelVertikal < 0) {
   WinkelVertikal = 360 + WinkelVertikal;
 }
}
// ===========================================
// Ende Tools
// Begin Turtle-Basics
void Forward(float Lang) {
 // move forward
 /*
  Malt ggf. (Wenn not Stifthoch gilt) eine Linie und
  ändert in jedem Fall die Turtle-Position.
  Die Linie verbindet alte und neue Turtle-Position.
  */
 float OldX, OldY, OldZ;
 float LangZ=0;
 float LangNeu=0;

 // Bereichsüberprüfung
 CheckWinkel();
 // alte Werte sichern:
 OldX = TurtleX;
 OldY = TurtleY;
 OldZ = TurtleZ;
 // Matrix befüllen
 pushMatrix();
 // translate and turn
 translate (OldX,OldY,OldZ);
 rotateX(WinkelVertikal);     // xrot
 rotateZ(WinkelHorizontal);   // zrot
 point (OldX,OldY,OldZ);
 // it was drawn at ( .., .., ..), store that location
 float x = modelX(OldX,OldY,OldZ);
 float y = modelY(OldX,OldY,OldZ);
 float z = modelZ(OldX,OldY,OldZ);
 // clear out all the transformations (read out Matrix)
 popMatrix();
 // get the (x, y, z) coordinate
 TurtleX = x; //  
 TurtleY = y; //  
 TurtleZ = z; //  
 if (!StiftHoch){
   stroke ( TurtleColor);
   line ( OldX, OldY, OldZ, TurtleX, TurtleY, TurtleZ );
 }
}
void Backward(int Length)
{
 // move backward  
 Forward (-Length);
}
void Right(int Winkel)
{
 // Turn right
 WinkelHorizontal += Winkel;
}
void Left(int Winkel)
{
 // Turn left
 Right(-Winkel);
}
void Up(int Winkel)
{  
 // Turn up
 WinkelVertikal += Winkel;
}
void Down(int Winkel)
{  
 // Turn down
 Up(-Winkel);
}
void JumpTo ( int a, int b, int c ) {
 // verwendet absolute Koordinaten
 TurtleX = a;
 TurtleY = b;
 TurtleZ = c;
}
// Ende Turtle Commands
/* ------------------------------------ */
// Beginn Turtle-Programme 1
void Quadrat(int Laenge)
{
 StiftHoch = false;
 for (int i = 0; i < 4; i = i+1)  
 {    
   Forward ( Laenge );
   Right (90);
 }
}
// ==================================================
// Beginn Turtle-Programme 2
void QuadratUp(int Laenge)
{
 StiftHoch = false;
 for (int i = 0; i < 4; i = i+1)  
 {    
   Forward ( Laenge );
   Up (90);
 }
}
void Wuerfel(int Laenge)
{
 // paint cube  
 println("Start Cube");
 StiftHoch = false;
 WinkelVertikal = 0 ;
 WinkelHorizontal = 0 ;
 // Start Position  
 TurtleX=560;
 TurtleY=340;
 TurtleZ=10;
 // for Number of Planes
 for (int j = 0; j < 4; j = j+1)  
 {
   // Sides of a plane
   for (int i = 0; i < 4; i = i+1)  
   {    
     Forward ( Laenge );
     Right (90);
   }  // Ende for i

   Forward(Laenge);
   Up(90);

 } // Ende for j
 println("Ende Cube");
}

void Igel3D(int Laenge)
{

 StiftHoch = false;
 lights();
 noStroke();

 // color ( TurtleColor);  

 for (int j = 0; j < 361; j = j+40)  
 {
   for (int i = 0; i < 361; i = i+40)  
   {    
     JumpTo ( 600,400,400 );
     WinkelVertikal = j;
     WinkelHorizontal = i;
     Forward ( Laenge );
   }
 }
}

void Spirale3D()
{
 JumpTo (600,400,10);
 Up(10);
 for (int j = 0; j < 360; j = j+2 )  {
   Right (10);
   Forward (14);
 } // Ende for
} // Ende function

// ================================================================================
==========
// Hauptprogramm

void draw()
{

 println ( "" );
 println ( "Starting." );

 JumpTo ( 300, 444, 30 );
 Quadrat (30);
 Up(90);
 Quadrat (30);

 // Wuerfel(40);
 // Quadrat(40);
 // Spirale3D();
 // Igel3D(90);

 noLoop();

 println ( "End. ");
 println ( "");  

}