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//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.3
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
// mcseemagg@yahoo.com
// http://www.antigrain.com
//----------------------------------------------------------------------------
//
// Bilinear 2D transformations
//
//----------------------------------------------------------------------------
#ifndef AGG_TRANS_BILINEAR_INCLUDED
#define AGG_TRANS_BILINEAR_INCLUDED
#include "agg_basics.h"
#include "agg_simul_eq.h"
namespace agg
{
//==========================================================trans_bilinear
class trans_bilinear
{
public:
//--------------------------------------------------------------------
trans_bilinear() : m_valid(false) {}
//--------------------------------------------------------------------
// Arbitrary quadrangle transformations
trans_bilinear(const double* src, const double* dst)
{
quad_to_quad(src, dst);
}
//--------------------------------------------------------------------
// Direct transformations
trans_bilinear(double x1, double y1, double x2, double y2,
const double* quad)
{
rect_to_quad(x1, y1, x2, y2, quad);
}
//--------------------------------------------------------------------
// Reverse transformations
trans_bilinear(const double* quad,
double x1, double y1, double x2, double y2)
{
quad_to_rect(quad, x1, y1, x2, y2);
}
//--------------------------------------------------------------------
// Set the transformations using two arbitrary quadrangles.
void quad_to_quad(const double* src, const double* dst)
{
double left[4][4];
double right[4][2];
unsigned i;
for(i = 0; i < 4; i++)
{
unsigned ix = i * 2;
unsigned iy = ix + 1;
left[i][0] = 1.0;
left[i][1] = src[ix] * src[iy];
left[i][2] = src[ix];
left[i][3] = src[iy];
right[i][0] = dst[ix];
right[i][1] = dst[iy];
}
m_valid = simul_eq<4, 2>::solve(left, right, m_mtx);
}
//--------------------------------------------------------------------
// Set the direct transformations, i.e., rectangle -> quadrangle
void rect_to_quad(double x1, double y1, double x2, double y2,
const double* quad)
{
double src[8];
src[0] = src[6] = x1;
src[2] = src[4] = x2;
src[1] = src[3] = y1;
src[5] = src[7] = y2;
quad_to_quad(src, quad);
}
//--------------------------------------------------------------------
// Set the reverse transformations, i.e., quadrangle -> rectangle
void quad_to_rect(const double* quad,
double x1, double y1, double x2, double y2)
{
double dst[8];
dst[0] = dst[6] = x1;
dst[2] = dst[4] = x2;
dst[1] = dst[3] = y1;
dst[5] = dst[7] = y2;
quad_to_quad(quad, dst);
}
//--------------------------------------------------------------------
// Check if the equations were solved successfully
bool is_valid() const { return m_valid; }
//--------------------------------------------------------------------
// Transform a point (x, y)
void transform(double* x, double* y) const
{
double tx = *x;
double ty = *y;
double xy = tx * ty;
*x = m_mtx[0][0] + m_mtx[1][0] * xy + m_mtx[2][0] * tx + m_mtx[3][0] * ty;
*y = m_mtx[0][1] + m_mtx[1][1] * xy + m_mtx[2][1] * tx + m_mtx[3][1] * ty;
}
//--------------------------------------------------------------------
class iterator_x
{
double inc_x;
double inc_y;
public:
double x;
double y;
iterator_x() {}
iterator_x(double tx, double ty, double step, const double m[4][2]) :
inc_x(m[1][0] * step * ty + m[2][0] * step),
inc_y(m[1][1] * step * ty + m[2][1] * step),
x(m[0][0] + m[1][0] * tx * ty + m[2][0] * tx + m[3][0] * ty),
y(m[0][1] + m[1][1] * tx * ty + m[2][1] * tx + m[3][1] * ty)
{
}
void operator ++ ()
{
x += inc_x;
y += inc_y;
}
};
iterator_x begin(double x, double y, double step) const
{
return iterator_x(x, y, step, m_mtx);
}
private:
double m_mtx[4][2];
bool m_valid;
};
}
#endif
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