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WS3.0: Pass tile_level, tile_width, tile_height

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Create Uniforms for the tile_level, tile_width and tile_height.

These can be used by the fragment shader to determine the level
of detail to render and also to perform samples for borders of
landclasses.
This commit is contained in:
Stuart Buchanan 2020-11-14 21:01:55 +00:00
parent 2fb20f793b
commit 94630733ff
1 changed files with 35 additions and 0 deletions
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35
simgear/scene/tgdb/VPBTechnique.cxx
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@ -1331,6 +1331,41 @@ void VPBTechnique::generateGeometry(BufferData& buffer, Locator* masterLocator,
}
#endif
// Tile-specific information for the shaders
osg::StateSet *ss = buffer._geode->getOrCreateStateSet();
osg::ref_ptr<osg::Uniform> level = new osg::Uniform("tile_level", _terrainTile->getTileID().level);
level->setDataVariance(osg::Object::STATIC);
ss->addUniform(level);
// Determine the x and y texture scaling. Has to be performed after we've generated all the vertices.
// Because the earth is round, each tile is not a rectangle. Apart from edge cases like the poles, the
// difference in axis length is < 1%, so we will just take the average.
osg::Vec3f bottom_left, bottom_right, top_left, top_right;
bool got_bl = VNG.vertex(0, 0, bottom_left);
bool got_br = VNG.vertex(0, VNG._numColumns - 1, bottom_right);
bool got_tl = VNG.vertex(VNG._numColumns - 1, 0, top_left);
bool got_tr = VNG.vertex(VNG._numColumns - 1, VNG._numRows -1, top_right);
float tile_width = 1.0;
float tile_height = 1.0;
if (got_bl && got_br && got_tl && got_tr) {
auto s = bottom_right - bottom_left;
auto t = top_left - bottom_left;
auto u = top_right - top_left;
auto v = top_right - bottom_right;
tile_width = 0.5 * (s.length() + u.length());
tile_height = 0.5 * (t.length() + v.length());
}
SG_LOG(SG_TERRAIN, SG_ALERT, "Tile Level " << _terrainTile->getTileID().level << " width " << tile_width << " height " << tile_height);
osg::ref_ptr<osg::Uniform> twu = new osg::Uniform("tile_width", tile_width);
twu->setDataVariance(osg::Object::STATIC);
ss->addUniform(twu);
osg::ref_ptr<osg::Uniform> thu = new osg::Uniform("tile_height", tile_height);
thu->setDataVariance(osg::Object::STATIC);
ss->addUniform(thu);
// Force build of KD trees?
if (osgDB::Registry::instance()->getBuildKdTreesHint()==osgDB::ReaderWriter::Options::BUILD_KDTREES &&
osgDB::Registry::instance()->getKdTreeBuilder())