Commit a065f0049ab9cfdae94c7064aa5c251cc129cb29
2008-05-06T21:19:42
* Refactor FTContour::ComputeOutsetPoint so that it's twice as short, even with the additional comments.
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diff --git a/src/FTContour.cpp b/src/FTContour.cpp
index fee1e78..86c59d4 100644
--- a/src/FTContour.cpp
+++ b/src/FTContour.cpp
@@ -93,53 +93,32 @@ void FTContour::evaluateCubicCurve(FTPoint A, FTPoint B, FTPoint C, FTPoint D)
}
}
-FTGL_DOUBLE FTContour::NormVector(const FTPoint &v)
-{
- return sqrt(v.X() * v.X() + v.Y() * v.Y());
-}
-void FTContour::RotationMatrix(const FTPoint &a, const FTPoint &b, FTGL_DOUBLE *matRot, FTGL_DOUBLE *invRot)
+// This function is a bit tricky. Given a path ABC, it returns the
+// coordinates of the outset point facing B on the left at a distance
+// of 64.0. Ask Sam for details, even ASCII art cannot possibly explain
+// this properly.
+FTPoint FTContour::ComputeOutsetPoint(FTPoint A, FTPoint B, FTPoint C)
{
- FTPoint abVect(b.X() - a.X(), b.Y() - a.Y(), 0);
- FTGL_DOUBLE abNorm = NormVector(abVect);
- invRot[0] = matRot[0] = -abVect.X() / abNorm;
- invRot[2] = matRot[1] = -abVect.Y() / abNorm;
- invRot[1] = matRot[2] = abVect.Y() / abNorm;
- invRot[3] = matRot[3] = -abVect.X() / abNorm;
-}
+ /* Build the rotation matrix from 'ba' vector */
+ FTPoint ba = (A - B).Normalise();
+ FTPoint bc = C - B;
-void FTContour::MultMatrixVect(FTGL_DOUBLE *mat, FTPoint &v)
-{
- FTPoint res;
- res.X(v.X() * mat[0] + v.Y() * mat[1]);
- res.Y(v.X() * mat[2] + v.Y() * mat[3]);
- v.X(res.X());
- v.Y(res.Y());
-}
+ /* Rotate bc to the left */
+ FTPoint tmp(bc.X() * -ba.X() + bc.Y() * -ba.Y(),
+ bc.X() * ba.Y() + bc.Y() * -ba.X());
-void FTContour::ComputeBisec(FTPoint &v)
-{
+ /* Compute the vector bisecting 'abc' */
FTGL_DOUBLE sgn = -64.0;
- if((v.Y() / NormVector(v)) < 0)
+ FTGL_DOUBLE norm = sqrt(tmp.X() * tmp.X() + tmp.Y() * tmp.Y());
+ if((tmp.Y() / norm) < 0)
sgn = 64.0;
- v.X(sgn * sqrt((NormVector(v) - v.X()) / (NormVector(v) + v.X())));
- v.Y(64.0);
-}
+ tmp.X(sgn * sqrt((norm - tmp.X()) / (norm + tmp.X())));
+ tmp.Y(64.0);
-FTPoint FTContour::ComputeOutsetPoint(FTPoint a, FTPoint b, FTPoint c)
-{
- FTGL_DOUBLE mat[4], inv[4];
- /* Build the rotation matrix from 'ab' vector */
- RotationMatrix(b, a, mat, inv);
- /* 'h' is the second vector 'bc' */
- FTPoint h = c - b;
- /* Apply the rotation to the second vector 'bc' */
- MultMatrixVect(mat, h);
- /* Compute the vector bisecting 'bh' */
- ComputeBisec(h);
- /* Apply the inverted rotation matrix to 'bh' */
- MultMatrixVect(inv, h);
- return h;
+ /* Rotate the new bc to the right */
+ return FTPoint(tmp.X() * -ba.X() + tmp.Y() * ba.Y(),
+ tmp.X() * -ba.Y() + tmp.Y() * -ba.X());
}
void FTContour::outsetContour()