Hi Gianni,
attached you find a quick example using a simple texture to let the user
"draw" different colors at different positions.
Basically it modifies the image data and samples it back when drawing.
I've created a mesh, but basically this would work with a simple quad
too. Is this maybe closer to what you want?
Cheers
Sebastian
SMesserschmidt wrote:
I can try to make a
minimal example, if you give me some time (I can do this after work).
Sebastian,
yes thanks, when you have time is fine. In the meanwhile I try to understand
the solutions you suggested.
Regards,
Gianni
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=68789#68789
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#include <osg/Geometry>
#include <osg/Geode>
#include <osg/MatrixTransform>
#include <osg/PolygonOffset>
#include <osgViewer/CompositeViewer>
#include <osgViewer/ViewerEventHandlers>
#include <osgGA/MultiTouchTrackballManipulator>
#include <osg/PolygonMode>
#include <osg/LineWidth>
#include <osg/ShadeModel>
#include <osgGA/StateSetManipulator>
#include <osgDB/ReadFile>
//#include <osgQt/GraphicsWindowQt>
#include <iostream>
const unsigned int DIMENSION = 64;
class SelectModelHandler : public osgGA::GUIEventHandler
{
public:
SelectModelHandler(osg::ref_ptr<osg::Group> group, osg::Image* image)
: _selector(0), currentPrimitiveSetIndex(0), _root(group),
_image(image)
{}
virtual bool handle(const osgGA::GUIEventAdapter& ea,
osgGA::GUIActionAdapter& aa)
{
if (ea.getEventType() == osgGA::GUIEventAdapter::RELEASE &&
ea.getButton() ==
osgGA::GUIEventAdapter::LEFT_MOUSE_BUTTON &&
ea.getModKeyMask() &
osgGA::GUIEventAdapter::MODKEY_CTRL)
{
osgViewer::View* viewer =
dynamic_cast<osgViewer::View*>(&aa);
if (viewer)
{
osg::ref_ptr<osgUtil::LineSegmentIntersector>
intersector = new osgUtil::LineSegmentIntersector(osgUtil::Intersector::WINDOW,
ea.getX(), ea.getY());
osgUtil::IntersectionVisitor
iv(intersector.get());
osg::Camera* camera = viewer->getCamera();
camera->accept(iv);
if (intersector->containsIntersections())
{
osgUtil::LineSegmentIntersector::Intersection result =
*(intersector->getIntersections().begin());
doUserOperations(result);
}
}
}
return false;
}
virtual void
doUserOperations(osgUtil::LineSegmentIntersector::Intersection& result)
{
osg::Geometry* geom =
dynamic_cast<osg::Geometry*>(result.drawable.get());
osg::Vec3 tc;
//the result seems slightly off
osg::Texture* tex = result.getTextureLookUp(tc);
if (tex && tex->getImage(0))
{
tex->getImage(0)->setColor(osg::Vec4d(1, 1, 1, 1), tc);
tex->getImage(0)->dirty();
tex->dirtyTextureObject();
}
}
protected:
osg::ref_ptr<osg::Geometry> _selector;
unsigned int currentPrimitiveSetIndex;
osg::ref_ptr<osg::Group> _root;
osg::ref_ptr<osg::Image> _image;
};
osg::Vec3Array* buildVertices(unsigned int num_rows)
{
//create a grid
osg::Vec3Array* v = new osg::Vec3Array(num_rows* num_rows);
for (unsigned int i = 0; i < num_rows; ++i)
{
for (unsigned int j = 0; j < num_rows; ++j)
{
(*v)[i * num_rows + j] = osg::Vec3(i, j, 0);
}
}
return v;
}
osg::Vec2Array* buildTexCoords(unsigned int num_rows)
{
//create a grid
osg::Vec2Array* v = new osg::Vec2Array(num_rows* num_rows);
for (unsigned int i = 0; i < num_rows; ++i)
{
for (unsigned int j = 0; j < num_rows; ++j)
{
(*v)[i * num_rows + j] = osg::Vec2(i /
static_cast<float>(num_rows -1), j / static_cast<float>(num_rows -1));
}
}
return v;
}
osg::DrawElementsUInt* buildElements(unsigned int num_rows)
{
osg::DrawElementsUInt* element = new
osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES);
for (unsigned int i = 0; i < num_rows - 1; ++i)
{
for (unsigned int j = 0; j < num_rows - 1; j++)
{
unsigned int offset = i * num_rows + j;
(*element).push_back(offset + 0);
(*element).push_back(offset + 1);
(*element).push_back(offset + num_rows);
(*element).push_back(offset + 1);
(*element).push_back(offset + num_rows + 1);
(*element).push_back(offset + num_rows);
}
}
return element;
}
osg::Vec4Array* buildColors(unsigned int num_rows)
{
osg::Vec4Array* colors = new osg::Vec4Array(num_rows * num_rows);
std::fill(std::begin(*colors), std::end(*colors),
osg::Vec4f(0.5,0.5,0.5,1.0));
return colors;
}
osg::Image* makeDataImage(unsigned int num_rows)
{
osg::Image* image = new osg::Image;
image->allocateImage(num_rows, num_rows, 1, GL_RGB, GL_UNSIGNED_BYTE);
for (unsigned int i = 0; i < num_rows; ++i)
{
for (unsigned int j = 0; j < num_rows; ++j)
{
osg::Vec2 uv(i / static_cast<float>(num_rows - 1), j /
static_cast<float>(num_rows - 1));
//checker
//image->setColor(osg::Vec4(i /
static_cast<float>(num_rows), j / static_cast<float>(num_rows), 0, 1), uv);
if (0 == i % 2 && j % 2 )
{
image->setColor(osg::Vec4(0, 0, 0, 1), uv);
}
else
{
image->setColor(osg::Vec4(1, 0, 0, 1), uv);
}
}
}
return image;
}
osg::Geometry* buildGeometry(osg::Image* image)
{
osg::Geometry* geometry = new osg::Geometry;
geometry->setDataVariance(osg::Object::DYNAMIC);
geometry->setUseVertexBufferObjects(true);
geometry->setVertexArray(buildVertices(DIMENSION));
//geometry->setColorArray(buildColors(DIMENSION),
osg::Array::BIND_PER_VERTEX);
geometry->setTexCoordArray(0, buildTexCoords(DIMENSION));
geometry->addPrimitiveSet(buildElements(DIMENSION));
osg::Texture2D* tex = new osg::Texture2D(image);
tex->setFilter(osg::Texture::MIN_FILTER, osg::Texture::NEAREST);
tex->setFilter(osg::Texture::MAG_FILTER, osg::Texture::NEAREST);
//osg::Texture2D* tex = new
osg::Texture2D(osgDB::readImageFile("d:/work/data/models/checker.tif"));
geometry->getOrCreateStateSet()->setTextureAttributeAndModes(0, tex,
osg::StateAttribute::ON);
return geometry;
}
osg::Node* createScene(osg::Image* image) {
osg::Geode* geode = new osg::Geode;
geode->addDrawable(buildGeometry(image));
return geode;
}
void createShader()
{
}
int main(int argc, char** argv)
{
osg::ArgumentParser arguments(&argc, argv);
osgViewer::Viewer viewer(arguments);
viewer.setUpViewInWindow(0, 0, 1000, 1000, 1);
osg::Image* data_image = makeDataImage(DIMENSION);
osg::ref_ptr<osg::Group> root = new osg::Group;
osg::ref_ptr<osg::Group> selection_root = new osg::Group;
root->addChild(createScene(data_image));
root->addChild(selection_root);
osg::ref_ptr<SelectModelHandler> selector = new
SelectModelHandler(selection_root, data_image);
viewer.setSceneData(root);
viewer.addEventHandler(selector.get());
viewer.setCameraManipulator(new osgGA::TrackballManipulator);
viewer.addEventHandler(new
osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()));
// add the window size toggle handler
viewer.addEventHandler(new osgViewer::WindowSizeHandler);
viewer.run();
}
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