nerdcruft/libcruft-util
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bezier: use the original distance method

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now the cubic solver is functional the old code appears correct, and it
seems to be more concise and more rigorously derived.
This commit is contained in:
Danny Robson 2015-02-03 02:20:12 +11:00
parent bb89f0e94f
commit 65fdb5e47a
1 changed files with 7 additions and 15 deletions
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22
bezier.cpp
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@ -244,7 +244,6 @@ util::bezier<S>::intersections (point2f p0, point2f p1) const
//-----------------------------------------------------------------------------
namespace util {
// TODO: use a more reliable method like [Xiao-Dia Chen 2010]
template <>
float
bezier<2>::distance (util::point2f target) const
@ -275,23 +274,15 @@ namespace util {
const auto M = target;
const auto M_ = p0 - M;
//float a = dot (B, B);
//float b = 3.f * dot (A, B);
//float c = 2.f * dot (A, A) + dot (M_, B);
//float d = dot (M_, A);
const util::vector2f p102 = {
2 * p1.x - p0.x - p2.x,
2 * p1.y - p0.y - p2.y
};
const float a = dot (B, 2.f * p102);
const float b = dot (B, 4.f * (p0 - p1)) + dot (A, 2.f * p102);
const float c = dot (B, 2.f * (M - p0)) + dot (A, 4.f * (p0 - p1));
const float d = dot (A, 2.f * (M - p0));
float a = dot (B, B);
float b = 3.f * dot (A, B);
float c = 2.f * dot (A, A) + dot (M_, B);
float d = dot (M_, A);
// We have our cubic, so pass off to the solver
auto solutions = util::polynomial::solve<3> ({a, b, c, d});
// Find the smallest distance and return
float dist = std::numeric_limits<float>::infinity ();
for (auto t: solutions) {
@ -343,6 +334,7 @@ float refine_cubic (util::bezier<3> b,
//-----------------------------------------------------------------------------
namespace util {
// TODO: use a more reliable method like [Xiao-Dia Chen 2010]
template <>
float
bezier<3>::distance (util::point2f target) const