[Gnash-commit] gnash ChangeLog server/shape.cpp

[Sandro Santilli]

CVSROOT:        /sources/gnash
Module name:    gnash
Changes by:     Sandro Santilli <strk>  07/11/12 10:22:41

Modified files:
        .              : ChangeLog 
        server         : shape.cpp 

Log message:
        pointOnCurve: quicker return for T in (0,1);
        withinSquareDistance: compute distance from segments, not points,
        reducing iterations from 100 to 10 with no detectable precision
        reduction.

CVSWeb URLs:
http://cvs.savannah.gnu.org/viewcvs/gnash/ChangeLog?cvsroot=gnash&r1=1.4831&r2=1.4832
http://cvs.savannah.gnu.org/viewcvs/gnash/server/shape.cpp?cvsroot=gnash&r1=1.48&r2=1.49

Patches:
Index: ChangeLog
===================================================================
RCS file: /sources/gnash/gnash/ChangeLog,v
retrieving revision 1.4831
retrieving revision 1.4832
diff -u -b -r1.4831 -r1.4832
--- ChangeLog   12 Nov 2007 09:38:28 -0000      1.4831
+++ ChangeLog   12 Nov 2007 10:22:40 -0000      1.4832
@@ -1,5 +1,9 @@
 2007-11-12 Sandro Santilli <address@hidden>
 
+       * server/shape.cpp: (pointOnCurve): quicker return for T in (0,1);
+         (withinSquareDistance): compute distance from segments, not points,
+         reducing iterations from 100 to 10 with no detectable precision
+         reduction.
        * testsuite/swfdec/swfdec_gnash_tester: it seems diff -u3 doesn't work
          anymore (as of GNU diffutils 2.8.1)
        * server/: shape.cpp, tesselate.h: minor cleanup

Index: server/shape.cpp
===================================================================
RCS file: /sources/gnash/gnash/server/shape.cpp,v
retrieving revision 1.48
retrieving revision 1.49
diff -u -b -r1.48 -r1.49
--- server/shape.cpp    12 Nov 2007 08:39:27 -0000      1.48
+++ server/shape.cpp    12 Nov 2007 10:22:41 -0000      1.49
@@ -59,6 +59,9 @@
 {
        // See 
http://en.wikipedia.org/wiki/B%C3%A9zier_curve#Quadratic_B.C3.A9zier_curves
 
+       if ( t == 0.0 ) return A;
+       else if ( t == 1.0 ) return B;
+
        point Q1(A, C, t);
        point Q2(C, B, t);
        point R = point(Q1, Q2, t);
@@ -393,40 +396,31 @@
                        //       defined by the triangle ACB and it's square 
                        //       distance from it is > then the requested one
 
-                       // Brute force, try 100 times or give up
+                       // Approximate the curve to segCount segments
+                       // and compute distance of query point from each
+                       // segment.
                        //
-                       // TODO: use a binary search like thing, in where
-                       //       we try to find the 't' value taking the average
-                       //       between the 2 best 't' values found so far
-                       //       (best is the ones giving closer distance)
+                       // TODO: find an apprpriate value for segCount based
+                       //       on rendering scale ?
                        //
                        float minDist = std::numeric_limits<float>::max();
-                       bool gettingCloser = false;
-                       int attempts = 100; 
-                       int i=0;
-                       for (; i<=attempts; ++i)
-                       {
-                               float t = (float)i/attempts;
-                               float d = edge::squareDistancePtCurve(A, C, B, 
p, t);
+                       int segCount = 10; 
+                       point p0 = A;
+                       for (int i=1; i<=segCount; ++i)
+                       {
+                               float t1 = (float)i/segCount;
+                               point p1 = edge::pointOnCurve(A, C, B, t1);
+
+                               // distance from point and segment being an 
approximation
+                               // of the curve 
+                               float d = edge::squareDistancePtSeg(p, p0, p1);
+
+                               //float d = edge::squareDistancePtCurve(A, C, 
B, p, t);
                                //log_debug("Factor %26.26g, distance %g (asked 
%g)", t, sqrt(d), sqrt(dist));
                                if ( d <= dist ) return true;
 
-                               if ( ! i ) minDist = d;
-                               else if ( d < minDist )
-                               {
-                                       minDist = d;
-                                       gettingCloser = true;
-                               }
-                               else if ( d > minDist )
-                               {
-                                       if ( gettingCloser )
-                                       {
-                                               // we were getting closer 
before...
-                                               break;
-                                       }
-                               }
+                               p0 = p1;
                        }
-                       // log_debug("Gave up at attempt %d", i);
                }
 
                px = np;