[osg-users] Fwd: generate height map using fractal

ami guru dosto.walla at gmail.com
Wed Mar 25 03:55:32 PDT 2009

Thanks Paul,

I tried to generate the terrain according to your suggestion, and it did
work for  incremental value multiplied with the value generated by the
fractals algorithm.

I was scaling the terrain that that is why the terrain looked so flat, so
rescale the normal hoping that the fractals will show up propertly. But the
same flat surface without the incremental value.


---------- Forwarded message ----------
From: Paul Martz <pmartz at skew-matrix.com>
Date: Sun, Mar 22, 2009 at 11:27 PM
Subject: Re: [osg-users] generate height map using fractal
To: OpenSceneGraph Users <osg-users at lists.openscenegraph.org>

 Wow. That article is like 13 years old. I think I wrote it with VC4 and
OpenGL 1.1.

As a debugging technique, try to separate the heightfield population
algorithm from the rendering issue. For example, try populating the
heightfield with an array of linearly increasing values and see if it
renders as you would expect. If it still renders wrong, then you know the
fractal algorithm isn't to blame and the problem is probably with how you
are using OSG. As a result, you'll have a much simpler example to post here.

I'd also suggest using Geometry instead of some other Drawable, as Geometry
is more flexible (you can run them through the Simplifier, for example).

Paul Martz
*Skew Matrix Software LLC*
+1 303 859 9466

*From:* osg-users-bounces at lists.openscenegraph.org [mailto:
osg-users-bounces at lists.openscenegraph.org] *On Behalf Of *ami guru
*Sent:* Sunday, March 22, 2009 7:46 AM
*To:* OpenSceneGraph Users
*Subject:* [osg-users] generate height map using fractal

Hello forum,

I have been using the Paul's article about generating terrain using fractals


I am populating the values in the osg height map structure.

But The rendering is giving me a flat surface.

I hope that Paul sees that as well.


  osg::ref_ptr<osg::Geode> myTerrain = new osg::Geode;

  //Now load the terrain

  osg::ref_ptr<osg::Node> terrainNode (osgDB::readNodeFile("Terrain2.3ds"));

  //generate the 2D fractal
  float *heightData = alloc2DFractArray(512);

  //Define some constants for the fractal terrain
  static const float DEF_HEIGHT_SCALE = 0.1f;
  static float TILING_SURFACE = 3;
  int randomSeed = 1;
  float H = 0.3;
  float iteration = 10;

  fill2DFractArray (heightData,512, randomSeed,DEF_HEIGHT_SCALE,H);

  //using the height field
  osg::ref_ptr<osg::HeightField> heightMap = new osg::HeightField;

  //allocate the space for the height field

  //populate the height map
  for(unsigned int i = 0; i < heightMap->getNumColumns();i++)
      for(unsigned int j = 0; j < heightMap->getNumRows();j++)
      int size = heightMap->getNumRows();

      //std::cout << heightMap->getHeight(i,j) << std::endl;

  //now add the drawable to  the terain
  myTerrain->addDrawable(new osg::ShapeDrawable(heightMap.get()));




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