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From Mathias Fröhlich, "I have a small update to the 'non convex polygon detection' in the ac3d loader

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that is used to tell if tesselation is required or if we will better leave a
polygon as is. It is still not perfect but catches some more cases."
This commit is contained in:
Robert Osfield
2006-12-19 17:30:22 +00:00
parent d9d3b99c2e
commit 4f32039f24
1 changed files with 21 additions and 2 deletions
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23
src/osgPlugins/ac3d/ac3d.cpp
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@@ -769,15 +769,34 @@ class SurfaceBin : public PrimitiveBin {
// Compute the normal times the enclosed area.
// During that check if the surface is convex. If so, put in the surface as such.
bool needTesselation = false;
osg::Vec3 prevEdgeNormal;
osg::Vec3 weightedNormal(0, 0, 0);
osg::Vec3 v0 = _vertexSet->getVertex(_refs[0].index);
for (unsigned i = 2; i < nRefs; ++i) {
osg::Vec3 side1 = _vertexSet->getVertex(_refs[i-1].index) - v0;
osg::Vec3 side2 = _vertexSet->getVertex(_refs[i].index) - v0;
osg::Vec3 newNormal = side1^side2;
if (3 < nRefs && newNormal*weightedNormal < 0)
if (!needTesselation)
{
needTesselation = true;
if (3 < nRefs && newNormal*weightedNormal < 0)
{
needTesselation = true;
}
if (i < 3)
{
prevEdgeNormal = newNormal;
}
else // if (3 <= i) // due to the for loop
{
osg::Vec3 sideim1 = _vertexSet->getVertex(_refs[i-1].index) - _vertexSet->getVertex(_refs[i-2].index);
osg::Vec3 sidei = _vertexSet->getVertex(_refs[i].index) - _vertexSet->getVertex(_refs[i-2].index);
osg::Vec3 edgeNormal = sideim1^sidei;
if (edgeNormal*prevEdgeNormal < 0)
{
needTesselation = true;
}
prevEdgeNormal = edgeNormal;
}
}
weightedNormal += newNormal;