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| author | Stanislaw Halik <sthalik@misaki.pl> | 2016-05-13 23:59:07 +0200 |
|---|---|---|
| committer | Stanislaw Halik <sthalik@misaki.pl> | 2016-05-13 23:59:07 +0200 |
| commit | ee18bc05ae54bd4b9a959ef544181dd8f597d955 (patch) | |
| tree | da5045cbd013f7411b1aac0b31a6cf6dcb26b34e /pose-widget | |
| parent | c772987dde5c42aa7f236ac7708f6e7d063d4aa7 (diff) | |
pose-widget: avoid too small denominator in perpendicular alignment
With a very small denominator in barycentric coords formula we get a
dissociated octopus that took PCP and LSD in one sitting.
A dead Octopus is just a bunch of blue spheres.
IOW, in division with too small a denominator operand the results are
numerically unstable.
This is done in the constructor in a convoluted way as to avoid
branching during calculating for each pixel.
Issue: #356
Reported-by: @MathijsG
Diffstat (limited to 'pose-widget')
| -rw-r--r-- | pose-widget/glwidget.cpp | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/pose-widget/glwidget.cpp b/pose-widget/glwidget.cpp index a2ed422e..f85e2ae1 100644 --- a/pose-widget/glwidget.cpp +++ b/pose-widget/glwidget.cpp @@ -11,7 +11,6 @@ #include <QPainter> #include <QPaintEvent> -//#include <QDebug> GLWidget::GLWidget(QWidget *parent) : QWidget(parent) { @@ -68,7 +67,17 @@ public: dot00 = v0.dot(v0); dot01 = v0.dot(v1); dot11 = v1.dot(v1); - invDenom = 1 / (dot00 * dot11 - dot01 * dot01); + const num denom = dot00 * dot11 - dot01 * dot01; + if (std::fabs(denom) < 1e-1f) + { + // for perpendicular plane, ensure u and v don't come out right + // this is done here to avoid branching below, in a hot loop + invDenom = -1; + dot00 = dot01 = dot11 = 1; + v0 = v1 = vec2(1, 1); + } + else + invDenom = 1 / denom; } bool barycentric_coords(const vec2& px, vec2& uv) const { |