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incomplete impl for chopping rational quads (need to "normalize" so I can get

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the new middle weight).



git-svn-id: http://skia.googlecode.com/svn/trunk@8668 2bbb7eff-a529-9590-31e7-b0007b416f81
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reed@google.com 2013-04-12 21:55:26 +00:00
parent 5ee449af74
commit 0d099557fe
1 changed files with 44 additions and 0 deletions
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44
src/core/SkGeometry.cpp
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@ -1401,6 +1401,34 @@ static SkScalar eval_ratquad(const SkScalar src[], SkScalar w, SkScalar t) {
return SkScalarDiv(numer, denom);
}
struct SkP3D {
SkScalar fX, fY, fZ;
void set(SkScalar x, SkScalar y, SkScalar z) {
fX = x; fY = y; fZ = z;
}
void projectDown(SkPoint* dst) const {
dst->set(fX / fZ, fY / fZ);
}
};
// we just return the middle 3 points, since the first and last are dups of src
//
static void p3d_interp(const SkScalar src[3], SkScalar dst[3], SkScalar t) {
SkScalar ab = SkScalarInterp(src[0], src[3], t);
SkScalar bc = SkScalarInterp(src[3], src[6], t);
dst[0] = ab;
dst[3] = SkScalarInterp(ab, bc, t);
dst[6] = bc;
}
static void ratquad_mapTo3D(const SkPoint src[3], SkScalar w, SkP3D dst[]) {
dst[0].set(src[0].fX * 1, src[0].fY * 1, 1);
dst[1].set(src[1].fX * w, src[1].fY * w, w);
dst[2].set(src[2].fX * 1, src[2].fY * 1, 1);
}
void SkRationalQuad::evalAt(SkScalar t, SkPoint* pt) const {
SkASSERT(t >= 0 && t <= SK_Scalar1);
@ -1411,5 +1439,21 @@ void SkRationalQuad::evalAt(SkScalar t, SkPoint* pt) const {
}
void SkRationalQuad::chopAt(SkScalar t, SkRationalQuad dst[2]) const {
SkP3D tmp[3], tmp2[3];
ratquad_mapTo3D(fPts, fW, tmp);
p3d_interp(&tmp[0].fX, &tmp2[0].fX, t);
p3d_interp(&tmp[0].fY, &tmp2[0].fY, t);
p3d_interp(&tmp[0].fZ, &tmp2[0].fZ, t);
dst[0].fPts[0] = fPts[0];
tmp2[0].projectDown(&dst[0].fPts[1]);
tmp2[1].projectDown(&dst[0].fPts[2]); dst[1].fPts[0] = dst[0].fPts[2];
tmp2[2].projectDown(&dst[1].fPts[1]);
dst[1].fPts[2] = fPts[2];
dst[0].fW = tmp2[0].fZ; // ?????
dst[1].fW = tmp2[2].fZ; // ?????
}