Repo created

3party/agg/agg_span_gouraud.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
+//----------------------------------------------------------------------------
+
+#ifndef AGG_SPAN_GOURAUD_INCLUDED
+#define AGG_SPAN_GOURAUD_INCLUDED
+
+#include "agg_basics.h"
+#include "agg_math.h"
+
+namespace agg
+{
+
+    //============================================================span_gouraud
+    template<class ColorT> class span_gouraud
+    {
+    public:
+        typedef ColorT color_type;
+
+        struct coord_type
+        {
+            double x;
+            double y;
+            color_type color;
+        };
+
+        //--------------------------------------------------------------------
+        span_gouraud() : 
+            m_vertex(0)
+        {
+            m_cmd[0] = path_cmd_stop;
+        }
+
+        //--------------------------------------------------------------------
+        span_gouraud(const color_type& c1,
+                     const color_type& c2,
+                     const color_type& c3,
+                     double x1, double y1,
+                     double x2, double y2,
+                     double x3, double y3,
+                     double d) : 
+            m_vertex(0)
+        {
+            colors(c1, c2, c3);
+            triangle(x1, y1, x2, y2, x3, y3, d);
+        }
+
+        //--------------------------------------------------------------------
+        void colors(ColorT c1, ColorT c2, ColorT c3)
+        {
+            m_coord[0].color = c1;
+            m_coord[1].color = c2;
+            m_coord[2].color = c3;
+        }
+
+        //--------------------------------------------------------------------
+        // Sets the triangle and dilates it if needed.
+        // The trick here is to calculate beveled joins in the vertices of the 
+        // triangle and render it as a 6-vertex polygon. 
+        // It's necessary to achieve numerical stability. 
+        // However, the coordinates to interpolate colors are calculated
+        // as miter joins (calc_intersection).
+        void triangle(double x1, double y1, 
+                      double x2, double y2,
+                      double x3, double y3,
+                      double d)
+        {
+            m_coord[0].x = m_x[0] = x1; 
+            m_coord[0].y = m_y[0] = y1;
+            m_coord[1].x = m_x[1] = x2; 
+            m_coord[1].y = m_y[1] = y2;
+            m_coord[2].x = m_x[2] = x3; 
+            m_coord[2].y = m_y[2] = y3;
+            m_cmd[0] = path_cmd_move_to;
+            m_cmd[1] = path_cmd_line_to;
+            m_cmd[2] = path_cmd_line_to;
+            m_cmd[3] = path_cmd_stop;
+
+            if(d != 0.0)
+            {   
+                dilate_triangle(m_coord[0].x, m_coord[0].y,
+                                m_coord[1].x, m_coord[1].y,
+                                m_coord[2].x, m_coord[2].y,
+                                m_x, m_y, d);
+
+                calc_intersection(m_x[4], m_y[4], m_x[5], m_y[5],
+                                  m_x[0], m_y[0], m_x[1], m_y[1],
+                                  &m_coord[0].x, &m_coord[0].y);
+
+                calc_intersection(m_x[0], m_y[0], m_x[1], m_y[1],
+                                  m_x[2], m_y[2], m_x[3], m_y[3],
+                                  &m_coord[1].x, &m_coord[1].y);
+
+                calc_intersection(m_x[2], m_y[2], m_x[3], m_y[3],
+                                  m_x[4], m_y[4], m_x[5], m_y[5],
+                                  &m_coord[2].x, &m_coord[2].y);
+                m_cmd[3] = path_cmd_line_to;
+                m_cmd[4] = path_cmd_line_to;
+                m_cmd[5] = path_cmd_line_to;
+                m_cmd[6] = path_cmd_stop;
+            }
+        }
+
+        //--------------------------------------------------------------------
+        // Vertex Source Interface to feed the coordinates to the rasterizer
+        void rewind(unsigned)
+        {
+            m_vertex = 0;
+        }
+
+        //--------------------------------------------------------------------
+        unsigned vertex(double* x, double* y)
+        {
+            *x = m_x[m_vertex];
+            *y = m_y[m_vertex];
+            return m_cmd[m_vertex++];
+        }
+
+    protected:
+        //--------------------------------------------------------------------
+        void arrange_vertices(coord_type* coord) const
+        {
+            coord[0] = m_coord[0];
+            coord[1] = m_coord[1];
+            coord[2] = m_coord[2];
+
+            if(m_coord[0].y > m_coord[2].y)
+            {
+                coord[0] = m_coord[2]; 
+                coord[2] = m_coord[0];
+            }
+
+            coord_type tmp;
+            if(coord[0].y > coord[1].y)
+            {
+                tmp      = coord[1];
+                coord[1] = coord[0];
+                coord[0] = tmp;
+            }
+
+            if(coord[1].y > coord[2].y)
+            {
+                tmp      = coord[2];
+                coord[2] = coord[1];
+                coord[1] = tmp;
+            }
+       }
+
+    private:
+        //--------------------------------------------------------------------
+        coord_type m_coord[3];
+        double m_x[8];
+        double m_y[8];
+        unsigned m_cmd[8];
+        unsigned m_vertex;
+    };
+
+}
+
+#endif
+