d3tesstransform Class Reference

Apply 2D transforms to the meshes points. More...

#include <d3tesstransform.h>

Collaboration diagram for d3tesstransform:

List of all members.

Public Member Functions
void	transEval ()
	Apply trans to all the points in the mesh.
	d3tesstransform (d3tess &_tess)
	Constructor.
void	rotate (double const theta)
	Rotate every point about the origin.
void	multiply (pt2c &row1, pt2c &row2)
	Multiply every point by the transform.
void	translate (pt2c &x)
	Shift every point in the mesh by x.
Public Attributes
d3tess &	tess
	The tessellation.
d2homogeneous	trans
	The current transform.

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Detailed Description

Apply 2D transforms to the meshes points.

There are two ways of using this class. Either use the direct methods to change the mesh or configure trans and call transEval().

The direct methods are simple and as they do not use a 3 by 3 matrix they are more efficient that the homogeneous transform.

But efficiency is relative. The homogeneous trans can have multiple transforms applied to it by multiplying with other d2homogeneous transforms.

It is also easy to pre compute the transform and forever use again by configuring trans and afterwards calling transEval() as opposed for example to using rotate(theta) which re calculates the tranform every time it is called.

Definition at line 31 of file d3tesstransform.h.

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Constructor & Destructor Documentation

d3tesstransform::d3tesstransform

(

d3tess &

_tess

)

Constructor.

Definition at line 7 of file d3tesstransform.cpp.

  : tess(_tess)
{
}

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Member Function Documentation

void d3tesstransform::multiply	(	pt2c &	row1,
		pt2c &	row2
	)

Multiply every point by the transform.

Definition at line 13 of file d3tesstransform.cpp.

References point2< T >::dot(), d3tess::pt, and tess.

Referenced by rotate().

{
  vector<pt3> & pt(tess.pt);
  uintc sz = pt.size();
  for ( uint i=1; i<sz; ++i )
  {
    pt2c w(pt[i]);
    pt[i].x = row1.dot(w);
    pt[i].y = row2.dot(w);
  }
}

void d3tesstransform::rotate

(

double const

theta

)

Rotate every point about the origin.

Definition at line 36 of file d3tesstransform.cpp.

References multiply().

Referenced by d3meshpartitiondraw::rotate().

{
  double const cos_t = cos(theta);
  double const sin_t = sin(theta);
  pt2c r1(cos_t,-sin_t);
  pt2c r2(sin_t,cos_t);

  multiply(r1,r2);
}

void d3tesstransform::transEval

(

)

Apply trans to all the points in the mesh.

Definition at line 47 of file d3tesstransform.cpp.

References d2homogeneous::matrixMultiply(), d3tess::pt, tess, trans, point3< T >::x, point3< T >::y, and point3< T >::z.

{
  vector<pt3> & pt(tess.pt);
  uintc sz = pt.size();
  point3<double> t;
  point3<double> *p;
  double c;
  for ( uint i=1; i<sz; ++i )
  {
    p = & pt[i]; 
    // Preserve the c value of the point
    c = p->z;
    t.x = p->x;
    t.y = p->y;
    // Homogeneous points have 1 as their z value
    t.z = 1.0;
    
    trans.matrixMultiply(*p,t);
   
    // Restore the c value of the point
    p->z = c;
  }
}

void d3tesstransform::translate

(

pt2c &

x

)

Shift every point in the mesh by x.

Definition at line 25 of file d3tesstransform.cpp.

References d3tess::pt, tess, point2< T >::x, and point2< T >::y.

Referenced by d3meshpartitiondraw::translate().

{
  vector<pt3> & pt(tess.pt);
  uintc sz = pt.size();
  for ( uint i=1; i<sz; ++i )
  {
    pt[i].x += x.x;
    pt[i].y += x.y;
  }
}

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Member Data Documentation

d3tess& d3tesstransform::tess

The tessellation.

Definition at line 36 of file d3tesstransform.h.

Referenced by multiply(), transEval(), and translate().

d2homogeneous d3tesstransform::trans

The current transform.

Definition at line 39 of file d3tesstransform.h.

Referenced by transEval().

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The documentation for this class was generated from the following files:

• cetessD2/d3tesstransform.h
• cetessD2/d3tesstransform.cpp