Hi,

I am creating a sketch similar in drawing functionality to Amit Pitaru's Sonic Wire Scultpure and I am using the TUIO library ( http://www.tuio.org/?processing ) and  MSARemote (http://www.memo.tv) to add multi-touch functionality.
Everything is working fine except for the z-rotation, I added a 2-finger gesture to rotate-Z but then the mouse coordinates do not match the line.

I used a little code from a post by Markavian here http://processing.org/discourse/yabb2/num_1117920593.html

I really wish my trig / understanding of 3d translations were better but I can't figure this out!

Can someone please tell me how to get my mouse's coordinates to remain relative to the z-rotation so that the line is drawn under the cursor

Here is my code (check applyRotation() & captureMouse()):
Code:

/**
 * 3d drawing tool using TUIO library
 * @author Kyle Phillips - http://labs.hapticdata.com
 */
 
import TUIO.*;
import processing.opengl.*;
import java.util.ArrayList;


TuioProcessing tuioClient;
 
float startRad = 0.0f;
float lastRad = 0.0f;
int depth = 50;
float x,y,z;
float angleX, angleY,angleZ;
float threshold = 0.3f;

int numCursors = 0;
ArrayList segments;
ArrayList currentSegment;


void setup()
{
  size(1280,720,OPENGL);
  segments = new ArrayList();

  frameRate(60);
  strokeWeight(2);
  background(64);

  tuioClient = new TuioProcessing(this);

}

void draw() { 
  // clear screen
  background(64);
  stroke(255,50);
  strokeWeight(1);
  line(0,height/2,width,height/2);
  line(width/2,0,width/2,height);  
  if(mousePressed && currentSegment != null) {
    // if the mouse is being dragged
    // capture new mouse coordinates
    captureMouse();

  } 

  Vector tuioCursorList = tuioClient.getTuioCursors(); 

  for( int j=0;j<tuioCursorList.size();j++)
  {
    TuioCursor tcur = (TuioCursor)tuioCursorList.elementAt(j);
    float vx = tcur.getXSpeed();
    float vy = tcur.getYSpeed();

    if(tuioCursorList.size() == 1)
    {
      lastRad = 0.0f;
      if(abs(vx) > threshold)angleX += radians(vx*-4);
      if(abs(vy) > threshold)angleY += radians(vy*-4);
    }
    else if(tuioCursorList.size() == 2)
    {
     
      //lastRotationZ -= rad;
      lastRad = getRotation(tuioCursorList);
      angleZ = startRad - lastRad;
      //println(angleZ*PI);
    }
    
    println(angleZ);
  }

  applyRotation();
  // draw the shape from the store arrays of points
  if(currentSegment != null) drawShape(); 
  
} 


float getRotation(Vector tuioCursorList)
{
   float y1 = ((TuioCursor)tuioCursorList.elementAt(0)).getY();
      float y2 = ((TuioCursor)tuioCursorList.elementAt(1)).getY();
      float x1 = ((TuioCursor)tuioCursorList.elementAt(0)).getX();
      float x2 = ((TuioCursor)tuioCursorList.elementAt(1)).getX();
      return atan2(y2-y1,x2-x1);
}

// markavian (2005|07|15)
// Reritten rotation method for all vertexes
// taken from david huebner's FVector class (2005|06|05)
void applyRotation(){ 
  for(int j=0;j<segments.size();j++)
  {
    ArrayList seg = (ArrayList)segments.get(j);
    // for every existing vertex in the array... 
    for(int i = 0; i < seg.size(); i++){ 

      float cosval, sinval;
      float tmp1, tmp2;

      PVector pv = (PVector) seg.get(i);
      x = pv.x; 
      y = pv.y; 
      z = pv.z; 

      cosval = cos(angleY); 
      sinval = sin(angleY);
      tmp1   = y*cosval - z*sinval;
      tmp2   = y*sinval + z*cosval;

      y = tmp1;
      z = tmp2;

      cosval = cos(angleX); 
      sinval = sin(angleX);
      tmp1   = x*cosval - z*sinval;
      tmp2   = x*sinval + z*cosval;
      
      x = tmp1;
      z = tmp2;
     

      pv.set(x,y,z); 
    } 
  }
  angleX = 0; 
  angleY = 0; 
  
  translate(width/2,height/2,-height/2);
  rotateZ(-angleZ);
  translate(-width/2,-height/2,height/2);
} 
// Draw the 'wire' onto the stage... 
void drawShape(){ 

  // markavian (2005|07|15) added translate because of change to applyRotation method
  translate(width/2, height/2);

  stroke(255,255,255,100);
  strokeWeight(2); 
  for(int l=0;l<segments.size();l++)
  {
    ArrayList seg = (ArrayList)segments.get(l);

    for(int j = 0; j < seg.size()-1; j++) { 
      PVector lastPV = (PVector)seg.get(j);
      PVector currentPV = (PVector)seg.get(j+1);
      line(lastPV.x, lastPV.y,lastPV.z,currentPV.x,currentPV.y,currentPV.z); 
    } 
  }
} 



void mousePressed() {
  currentSegment = new ArrayList();
  segments.add(currentSegment);
}




// Capture the mouse coordinates. 
void captureMouse(){ 

  int xpoint = mouseX-width/2; 
  int ypoint = mouseY-height/2; 
  int zpoint = 1;
  currentSegment.add(new PVector(xpoint,ypoint,zpoint));
 
} 

void keyPressed()
{
  if(key == 'c')
  {
    segments = new ArrayList();
  }
}

void updateTuioObject(TuioObject tobj)
{
}

void addTuioCursor(TuioCursor tcur)
{

  if(numCursors == 1)
  {
    Vector tuioCursorList = tuioClient.getTuioCursors();
    startRad = getRotation(tuioCursorList) + angleZ;
  }
  
  numCursors++;
}

void removeTuioCursor(TuioCursor tcur)
{
  numCursors--;
}

 

please help!

thank you so much!

I'm really glad that you were able to provide me with a solution and an explanation; I completely understand, thanks again!

-Kyle