Classify Beziers, use DeCasteljau for CPU renderer

[ipdf/code.git] / src / bezier.h

diff --git a/src/bezier.h b/src/bezier.h
index 7ff4f87..a7124af 100644 (file)
--- a/src/bezier.h
+++ b/src/bezier.h
@@ -25,16 +25,72 @@ namespace IPDF
                Real x2; Real y2;
                Real x3; Real y3;
                
-               typedef enum {LINE, QUADRATIC, CUSP, LOOP, SERPENTINE} Type;
+               typedef enum {UNKNOWN, LINE, QUADRATIC, CUSP, LOOP, SERPENTINE} Type;
                Type type;
                
                Bezier() = default; // Needed so we can fread/fwrite this struct... for now.
-               Bezier(Real _x0, Real _y0, Real _x1, Real _y1, Real _x2, Real _y2, Real _x3, Real _y3) : x0(_x0), y0(_y0), x1(_x1), y1(_y1), x2(_x2), y2(_y2), x3(_x3), y3(_y3) 
+               Bezier(Real _x0, Real _y0, Real _x1, Real _y1, Real _x2, Real _y2, Real _x3, Real _y3) : x0(_x0), y0(_y0), x1(_x1), y1(_y1), x2(_x2), y2(_y2), x3(_x3), y3(_y3), type(UNKNOWN)
                {
-                       //TODO: classify the curve
-                       type = SERPENTINE;
+
                }
                
+               const Type & GetType()
+               {
+                       if (type != Bezier::UNKNOWN)
+                               return type;
+                       // From Loop-Blinn 2005, with w0 == w1 == w2 == w3 = 1
+                       // Transformed control points: (a0 = x0, b0 = y0)
+                       Real a1 = (x1-x0)*3;
+                       Real a2 = (x0- x1*2 +x2)*3;
+                       Real a3 = (x3 - x0 + (x1 - x2)*3);
+                       
+                       Real b1 = (y1-y0)*3;
+                       Real b2 = (y0- y1*2 +y2)*3;
+                       Real b3 = (y3 - y0 + (y1 - y2)*3);
+                       
+                       // d vector (d0 = 0 since all w = 1)
+                       Real d1 = a2*b3 - a3*b2;
+                       Real d2 = a3*b1 - a1*b3;
+                       Real d3 = a1*b2 - a2*b1;
+                       
+                       if (d1 == d2 && d2 == d3 && d3 == 0)
+                       {
+                               type = LINE;
+                               //Debug("LINE %s", Str().c_str());
+                               return type;
+                       }
+                       
+                       Real delta1 = -d1*d1;
+                       Real delta2 = d1*d2;
+                       Real delta3 = d1*d3 -d2*d2;
+                       if (delta1 == delta2 && delta2 == delta3 && delta3 == 0)
+                       {
+                               type = QUADRATIC;
+                               
+                               //Debug("QUADRATIC %s", Str().c_str());
+                               return type;
+                       }
+                       
+                       Real discriminant = d1*d3*4 -d2*d2;
+                       if (discriminant == 0)
+                       {
+                               type = CUSP;
+                               //Debug("CUSP %s", Str().c_str());
+                       }
+                       else if (discriminant > 0)
+                       {
+                               type = SERPENTINE;
+                               //Debug("SERPENTINE %s", Str().c_str());
+                       }
+                       else
+                       {
+                               type = LOOP;
+                               //Debug("LOOP %s", Str().c_str());
+                       }
+                       return type;
+               }
+               
+               
                std::string Str() const
                {
                        std::stringstream s;
@@ -46,7 +102,7 @@ namespace IPDF
                 * Construct absolute control points using relative control points to a bounding rectangle
                 * ie: If cpy is relative to bounds rectangle, this will be absolute
                 */
-               Bezier(const Bezier & cpy, const Rect & t = Rect(0,0,1,1)) : x0(cpy.x0), y0(cpy.y0), x1(cpy.x1), y1(cpy.y1), x2(cpy.x2),y2(cpy.y2), x3(cpy.x3), y3(cpy.y3), type(cpy.type)
+               Bezier(const Bezier & cpy, const Rect & t = Rect(0,0,1,1)) : x0(cpy.x0), y0(cpy.y0), x1(cpy.x1), y1(cpy.y1), x2(cpy.x2),y2(cpy.y2), x3(cpy.x3), y3(cpy.y3), type(UNKNOWN)
                {
                        x0 *= t.w;
                        y0 *= t.h;