Hi all,
I also need to query the height of the ocean. Based on Dimitrios posted
code, I modified it to do a bi-linear interpolation. Below is the code I
would like to share. Should there be general interest in height query of
the ocean, then it would be good to put this or similar code in the
repository.
Note: This method always gets the height from the highest detail mipmap.
float FFTOceanSurface::getHeightAt(float x, float y )
{
if(_isDirty)
build();
// Translate x, y to oceanSurface origin coordinates
float oceanX = -_startPos.x() + x;
float oceanY = _startPos.y() - y;
// Calculate the corresponding tile on the ocean surface
unsigned int ix = oceanX/_tileResolution;
unsigned int iy = oceanY/_tileResolution ;
// Test if the tile is valid
if( ix < _numTiles && iy < _numTiles ) {
// Select the tile for the specific frame
const OceanTile& data = _mipmapData[_oldFrame][0];
// Calculate the coordinates on the specific tile we're
intersted
float tile_x = oceanX - ix*_tileResolution;
float tile_y = oceanY - iy*_tileResolution;
// Do the bi-linear interpolation
return data.biLinearInterp(tile_x, tile_y);
}
else
{
return 0.f;
}
}
float OceanTile::biLinearInterp(float x, float y ) const
{
float dx = x/_spacing;
float dy = y/_spacing;
unsigned int ix = dx;
unsigned int iy = dy;
dx -= ix;
dy -= iy;
float s00 = getVertex(ix , iy ).z();
float s01 = getVertex(ix+1, iy ).z();
float s10 = getVertex(ix , iy+1).z();
float s11 = getVertex(ix+1, iy+1).z();
return s00*(1.f-dx)*(1.f-dy) + s01*dx*(1.f-dy) + s10*(1.f-dx)*dy +
s11*dx*dy;
}
Other topic:
When you include <windows.h> before <osgOcean/OceanScene> there is a
conflict with the macro near/far of the windows header (line 261 and 275
of OceanScene). I can't change the include order in my project so I had
to use some undef pragmas to successfully compile the code.
To avoid these windows header conflicts, would it be possible to change
OceanScene headers from:
inline void setDOFNear( float near ) {
_dofNear = near;
...
inline void setDOFFar(float far ) {
_dofFar = far;
to
inline void setDOFNear( float dofNear ) {
_dofNear = dofNear;
...
inline void setDOFFar(float dofFar ) {
_dofFar = dofFar;
Regards,
Jean-Claude
On Wed, 30 Sep 2009 09:33 +0100, "Kim Bale" <kcb...@googlemail.com>
wrote:
> Hi Dimitrios,
>
> The interpolation function in OceanTile works on indices fetching the
> vertices from the vertex array within it. So you pass it the 4 unique
> row/column indices that make up the surrounding four points and then a
> row and a column index for the target point (tx & ty).
>
> For your application you'll need to make a modified version that takes
> in x,y coords rather than indices but the mathematical approach is the
> same.
>
> Regards,
>
> Kim.
>
>
>
> 2009/9/30 Dimitrios Filiagos <dfili...@yahoo.com>:
> > Hi,
> > I saw the Update function and understood that you're absolutely right!
> > I saw more accurate results also!
> > Yesterday I changed the function to retrieve the normal too. Now with the
> > normal I can make the models not only to move up and down but rotate also
> > when a wave passes.
> >
> > I will try to use biLinearInterp to interpolate the height between four
> > vertices. For that function you must provide the indices (x,y) of three
> > vertices? Is that correct?
> >
> >
> > Thanks
> >
> > Cheers,
> > Dimitrios
> >
> > ------------------
> > Read this topic online here:
> > http://forum.openscenegraph.org/viewtopic.php?p=17735#17735
> >
> >
> >
> >
> >
> > _______________________________________________
> > osg-users mailing list
> > osg-users@lists.openscenegraph.org
> > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
> >
> _______________________________________________
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--
Jean-Claude Monnin
jc_mon...@emailplus.org
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