intersect.java

JAVA3D矩陈的相关类

    else if(dir.y != 0.0) {
      if(pnt.x != ori.x)
	return false;
      flag = 1;
      dist[0] = (pnt.y - ori.y)/dir.y;
    }
    else if(dir.z != 0.0) {
      if((pnt.x != ori.x)||(pnt.y != ori.y))
	return false;
      flag = 2;
      dist[0] = (pnt.z - ori.z)/dir.z;
           
    }
    else
      return false;

    if(dist[0] < 0.0)
      return false;

    if(flag == 0) {
      temp = ori.y + dist[0] * dir.y;
      if((pnt.y < (temp - Double.MIN_VALUE)) || (pnt.y > (temp + Double.MIN_VALUE)))
	return false;    
    }
    
    if(flag < 2) {
      temp = ori.z + dist[0] * dir.z;
      if((pnt.z < (temp - Double.MIN_VALUE)) || (pnt.z > (temp + Double.MIN_VALUE)))
	return false;
    }

    return true;
    
  }

  private static boolean rayAndPoly( Point3d coordinates[], 
				     PickRay ray, double dist[] ) {
    
    Vector3d vec0 = new Vector3d(); // Edge vector from point 0 to point 1;
    Vector3d vec1 = new Vector3d(); // Edge vector from point 0 to point 2 or 3;
    Vector3d pNrm = new Vector3d();
    double  absNrmX, absNrmY, absNrmZ, pD = 0.0;
    Vector3d tempV3d = new Vector3d();
    double pNrmDotrDir = 0.0; 
    int axis, nc, sh, nsh;
    Point3d origin = new Point3d();
    Vector3d direction = new Vector3d();

    Point3d iPnt = new Point3d(); // Point of intersection.
    
    double uCoor[] = new double[4]; // Only need to support up to quad.
    double vCoor[] = new double[4];
    double tempD;

    int i, j;

    // Compute plane normal.
    for(i=0; i<coordinates.length-1;) {
      vec0.x = coordinates[i+1].x - coordinates[i].x;
      vec0.y = coordinates[i+1].y - coordinates[i].y;
      vec0.z = coordinates[i+1].z - coordinates[i++].z;
      if(vec0.length() > 0.0)
	break;
    }
        
    for(j=i; j<coordinates.length-1; j++) {
      vec1.x = coordinates[j+1].x - coordinates[j].x;
      vec1.y = coordinates[j+1].y - coordinates[j].y;
      vec1.z = coordinates[j+1].z - coordinates[j].z;
      if(vec1.length() > 0.0)
	break;
    }
    
    if(j == (coordinates.length-1)) {
      // System.out.println("(1) Degenerated polygon.");
      return false;  // Degenerated polygon.
    }

    /* 
       System.out.println("Triangle/Quad :");
       for(i=0; i<coordinates.length; i++) 
       System.out.println("P" + i + " " + coordinates[i]);
       */

    pNrm.cross(vec0,vec1);
    
    if(pNrm.length() == 0.0) {
      // System.out.println("(2) Degenerated polygon.");
      return false;  // Degenerated polygon.
    }

    ray.get(origin, direction);
    // System.out.println("Ray orgin : " + origin + " dir " + direction);

    // Compute plane D.
    tempV3d.set((Tuple3d) coordinates[0]);
    pD = pNrm.dot(tempV3d);

    pNrmDotrDir = pNrm.dot(direction);
    
    // Ray is parallel to plane. 
    if(pNrmDotrDir== 0.0) {
      // System.out.println("Ray is parallel to plane.");
      return false;        
    }

    tempV3d.set((Tuple3d) origin);

    dist[0] = (pD - pNrm.dot(tempV3d))/ pNrmDotrDir;

    // Ray intersects the plane behind the ray's origin.
    if(dist[0] < 0.0 ) {
      // System.out.println("Ray intersects the plane behind the ray's origin.");
      return false;
    }

    // Now, one thing for sure the ray intersects the plane.
    // Find the intersection point.
    iPnt.x = origin.x + direction.x * dist[0];
    iPnt.y = origin.y + direction.y * dist[0];
    iPnt.z = origin.z + direction.z * dist[0];
    
    // System.out.println("dist " + dist[0] + " iPnt : " + iPnt);

    // Project 3d points onto 2d plane and apply Jordan curve theorem. 
    // Note : Area of polygon is not preserve in this projection, but
    // it doesn't matter here. 
    
    // Find the axis of projection.
    absNrmX = Math.abs(pNrm.x);
    absNrmY = Math.abs(pNrm.y);
    absNrmZ = Math.abs(pNrm.z);

    if(absNrmX > absNrmY)
      axis = 0;
    else 
      axis = 1;

    if(axis == 0) {
      if(absNrmX < absNrmZ)
	axis = 2;
    }    
    else if(axis == 1) {
      if(absNrmY < absNrmZ)
	axis = 2;
    }    
    
    // System.out.println("Normal " + pNrm + " axis " + axis );
    
    for(i=0; i<coordinates.length; i++) {
      switch (axis) {
      case 0:
	uCoor[i] = coordinates[i].y - iPnt.y;
	vCoor[i] = coordinates[i].z - iPnt.z;
	break;
	
      case 1:
      	uCoor[i] = coordinates[i].x - iPnt.x;
	vCoor[i] = coordinates[i].z - iPnt.z;
	break;
	
      case 2:
	uCoor[i] = coordinates[i].x - iPnt.x;
	vCoor[i] = coordinates[i].y - iPnt.y;
	break;      
      } 
     
      // System.out.println("i " + i + " u " + uCoor[i] + " v " + vCoor[i]); 
    }
    
    // initialize number of crossing, nc.
    nc = 0;
   
    if(vCoor[0] < 0.0)
      sh = -1;
    else 
      sh = 1;

    for(i=0; i<coordinates.length; i++) {
      j= i+1;
      if(j==coordinates.length)
	j=0;
      
      if(vCoor[j] < 0.0)
	nsh = -1;
      else
	nsh = 1;

      if(sh != nsh) {
	if((uCoor[i] > 0.0) && (uCoor[j] > 0.0)) {
	  // This line must cross U+.
	  nc++;
	}
	else if((uCoor[i] > 0.0) || (uCoor[j] > 0.0)) {
	  // This line might cross U+. We need to compute intersection on U azis.
	  tempD = uCoor[i]-vCoor[i]*(uCoor[j]-uCoor[i])/(vCoor[j]-vCoor[i]);
	  if(tempD > 0)
	    // This line cross U+.
	    nc++;	  
	}	
	sh = nsh;
      } // sh != nsh
    }

    // System.out.println("nc " + nc);
   
    if((nc%2) == 1) {
      
	// calculate the distance
	dist[0] *= direction.length();

	// System.out.println("Ray Intersected!");	
	/* 
	   System.out.println("Ray orgin : " + origin + " dir " + direction);
	   System.out.println("Triangle/Quad :");
	   for(i=0; i<coordinates.length; i++) 
	   System.out.println("P" + i + " " + coordinates[i]);
	   System.out.println("dist " + dist[0] + " iPnt : " + iPnt);
	   */
	return true;
    }
    else {
	// System.out.println("Ray Not Intersected!");
	return false;
    }
  }

  /**
   *  Return true if triangle or quad intersects with segment and the distance is 
   *  stored in dist[0].
   * */
     
  private static boolean segmentAndPoly( Point3d coordinates[], 
						  PickSegment segment, 
						  double dist[] ) {
    
    Vector3d vec0 = new Vector3d(); // Edge vector from point 0 to point 1;
    Vector3d vec1 = new Vector3d(); // Edge vector from point 0 to point 2 or 3;
    Vector3d pNrm = new Vector3d();
    double  absNrmX, absNrmY, absNrmZ, pD = 0.0;
    Vector3d tempV3d = new Vector3d();
    Vector3d direction = new Vector3d();
    double pNrmDotrDir = 0.0; 
    int axis, nc, sh, nsh;
    Point3d start = new Point3d(); 
    Point3d end = new Point3d(); 

    Point3d iPnt = new Point3d(); // Point of intersection.
    
    double uCoor[] = new double[4]; // Only need to support up to quad.
    double vCoor[] = new double[4];
    double tempD;

    int i, j;

    // Compute plane normal.
    for(i=0; i<coordinates.length-1;) {
      vec0.x = coordinates[i+1].x - coordinates[i].x;
      vec0.y = coordinates[i+1].y - coordinates[i].y;
      vec0.z = coordinates[i+1].z - coordinates[i++].z;
      if(vec0.length() > 0.0)
	break;
    }
        
    for(j=i; j<coordinates.length-1; j++) {
      vec1.x = coordinates[j+1].x - coordinates[j].x;
      vec1.y = coordinates[j+1].y - coordinates[j].y;
      vec1.z = coordinates[j+1].z - coordinates[j].z;
      if(vec1.length() > 0.0)
	break;
    }
    
    if(j == (coordinates.length-1)) {
      // System.out.println("(1) Degenerated polygon.");
      return false;  // Degenerated polygon.
    }
    
    /* 
       System.out.println("Triangle/Quad :");
       for(i=0; i<coordinates.length; i++) 
       System.out.println("P" + i + " " + coordinates[i]);
       */

    pNrm.cross(vec0,vec1);
    
    if(pNrm.length() == 0.0) {
      // System.out.println("(2) Degenerated polygon.");
      return false;  // Degenerated polygon.
    }
    // Compute plane D.
    tempV3d.set((Tuple3d) coordinates[0]);
    pD = pNrm.dot(tempV3d);

    segment.get(start, end);
    // System.out.println("Segment start : " + start + " end " + end);

    direction.x = end.x - start.x;
    direction.y = end.y - start.y;
    direction.z = end.z - start.z;

    pNrmDotrDir = pNrm.dot(direction);
    
    // Segment is parallel to plane. 
    if(pNrmDotrDir== 0.0) {
      // System.out.println("Segment is parallel to plane.");
      return false;        
    }

    tempV3d.set((Tuple3d) start);

    dist[0] = (pD - pNrm.dot(tempV3d))/ pNrmDotrDir;

    // Segment intersects the plane behind the segment's start.
    // or exceed the segment's length.
    if((dist[0] < 0.0 ) || (dist[0] > 1.0 )) {
      // System.out.println("Segment intersects the plane behind the start or exceed end.");
      return false;
    }

    // Now, one thing for sure the segment intersect the plane.
    // Find the intersection point.
    iPnt.x = start.x + direction.x * dist[0];
    iPnt.y = start.y + direction.y * dist[0];
    iPnt.z = start.z + direction.z * dist[0];
    
    // System.out.println("dist " + dist[0] + " iPnt : " + iPnt);

    // Project 3d points onto 2d plane and apply Jordan curve theorem. 
    // Note : Area of polygon is not preserve in this projection, but
    // it doesn't matter here. 
    
    // Find the axis of projection.
    absNrmX = Math.abs(pNrm.x);
    absNrmY = Math.abs(pNrm.y);
    absNrmZ = Math.abs(pNrm.z);

    if(absNrmX > absNrmY)
      axis = 0;
    else 
      axis = 1;

    if(axis == 0) {
      if(absNrmX < absNrmZ)
	axis = 2;
    }    
    else if(axis == 1) {
      if(absNrmY < absNrmZ)
	axis = 2;
    }    
    
    // System.out.println("Normal " + pNrm + " axis " + axis );
    
    for(i=0; i<coordinates.length; i++) {
      switch (axis) {
      case 0:
	uCoor[i] = coordinates[i].y - iPnt.y;
	vCoor[i] = coordinates[i].z - iPnt.z;
	break;
	
      case 1:
      	uCoor[i] = coordinates[i].x - iPnt.x;
	vCoor[i] = coordinates[i].z - iPnt.z;
	break;
	
      case 2:
	uCoor[i] = coordinates[i].x - iPnt.x;
	vCoor[i] = coordinates[i].y - iPnt.y;
	break;      
      } 
     
      // System.out.println("i " + i + " u " + uCoor[i] + " v " + vCoor[i]); 
    }
    
    // initialize number of crossing, nc.
    nc = 0;
   
    if(vCoor[0] < 0.0)
      sh = -1;
    else 
      sh = 1;

    for(i=0; i<coordinates.length; i++) {
      j= i+1;
      if(j==coordinates.length)
	j=0;
      
      if(vCoor[j] < 0.0)
	nsh = -1;
      else
	nsh = 1;

      if(sh != nsh) {
	if((uCoor[i] > 0.0) && (uCoor[j] > 0.0)) {
	  // This line must cross U+.
	  nc++;
	}
	else if((uCoor[i] > 0.0) || (uCoor[j] > 0.0)) {
	  // This line might cross U+. We need to compute intersection on U azis.
	  tempD = uCoor[i]-vCoor[i]*(uCoor[j]-uCoor[i])/(vCoor[j]-vCoor[i]);
	  if(tempD > 0)
	    // This line cross U+.
	    nc++;	  
	}	
	sh = nsh;
      } // sh != nsh
    }

    // System.out.println("nc " + nc);
   
    if((nc%2) == 1) {
      
	// calculate the distance
	dist[0] *= direction.length();
	
	// System.out.println("Segment Intersected!");	
	/* 
	   System.out.println("Segment orgin : " + start + " dir " + direction);
	   System.out.println("Triangle/Quad :");
	   for(i=0; i<coordinates.length; i++) 
	   System.out.println("P" + i + " " + coordinates[i]);
	   System.out.println("dist " + dist[0] + " iPnt : " + iPnt);
	   */
	return true;
    }
    else {
	// System.out.println("Segment Not Intersected!");
	return false;
    }
  }
    
}