FGFS-4.1/OpenSceneGraph
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From Hatwig Wiesmann, "osg::TransferFunction1D::assignToImage may assign NaN values to the image in case an underflow inside the method occurs. This underflow can be reproduced by the following call sequence:

Browse Source 
osg::TransferFunction1D* tf(new osg::TransferFunction1D());

tf->allocate(18);
tf->setColor(-10000,osg::Vec4(        1.0,        1.0,        1.0,1.0));
tf->setColor(-1e-6,osg::Vec4(        1.0,        1.0,        1.0,1.0));
tf->setColor(   0,osg::Vec4(        0.0,        0.0,        1.0,1.0));

Remark: The value -1e-6 may be added (falsely) because of a rounding error.

The attached fix prevents assigning NaN values to the image.
"
This commit is contained in:
Robert Osfield 2010-04-23 09:29:50 +00:00
parent 75fc7b6598
commit 64acd4df54
1 changed files with 16 additions and 13 deletions
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29
src/osg/TransferFunction.cpp
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@ -69,32 +69,35 @@ void TransferFunction1D::clear(const osg::Vec4& color)
void TransferFunction1D::assignToImage(float lower_v, const osg::Vec4& lower_c, float upper_v, const osg::Vec4& upper_c)
{
int endPos = getNumberImageCells()-1;
float minimum = _colorMap.begin()->first;
float maximum = _colorMap.rbegin()->first;
float endPos = float(getNumberImageCells()-1);
float multiplier = endPos/(maximum - minimum);
float multiplier = float(endPos)/(maximum - minimum);
osg::Vec4* imageData = reinterpret_cast<osg::Vec4*>(_image->data());
float lower_iPos = (lower_v - minimum)*multiplier;
float upper_iPos = (upper_v - minimum)*multiplier;
float start_iPos = ceilf(lower_iPos);
if (start_iPos<0.0f) start_iPos=0.0f;
if (start_iPos>endPos) return;
int start_iPos = static_cast<int>(ceilf(lower_iPos));
if (start_iPos < 0) start_iPos = 0;
if (start_iPos > endPos) return;
float end_iPos = floorf(upper_iPos);
if (end_iPos<0.0f) return;
if (end_iPos>endPos) end_iPos=endPos;
int end_iPos = static_cast<int>(floorf(upper_iPos));
if (end_iPos < 0) return;
if (end_iPos > endPos) end_iPos = endPos;
//osg::notify(osg::NOTICE)<<"TransferFunction1D::assignToImage[lower_v="<<lower_v<<", lower_c="<<lower_c<<", upper_v="<<upper_v<<" upper_c="<<upper_c<<std::endl;
//osg::notify(osg::NOTICE)<<" lower_iPos="<<lower_iPos<<" start_iPpos="<<start_iPos<<std::endl;
//osg::notify(osg::NOTICE)<<" upper_iPos="<<upper_iPos<<" end_iPpos="<<end_iPos<<std::endl;
Vec4 delta_c = (upper_c-lower_c)/(upper_iPos-lower_iPos);
unsigned int i=static_cast<unsigned int>(start_iPos);
for(float iPos=start_iPos;
iPos<=end_iPos;
++iPos, ++i)
// upper_iPos can be identical to lower_iPos in case an underflow occurred while calculation the values;
// if both values are identical delta_c is identical to the null vector otherwise it is calculated like follows:
Vec4 delta_c;
if (upper_iPos != lower_iPos)
delta_c = (upper_c-lower_c)/(upper_iPos-lower_iPos);
float iPos = static_cast<float>(start_iPos);
for(int i=start_iPos; i<=end_iPos; ++i, ++iPos)
{
imageData[i] = lower_c + delta_c*(iPos-lower_iPos);
//osg::notify(osg::NOTICE)<<" imageData["<<i<<"] = "<<imageData[i]<<std::endl;