Repo created

3party/agg/agg_trans_bilinear.h

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+//----------------------------------------------------------------------------
+// Anti-Grain Geometry - Version 2.4
+// 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