osg实现天空盒

osg实现天空盒

class MoveEarthySkyWithEyePointTransform : public osg::Transform {

public:

virtual bool computeLocalToWorldMatrix(osg::Matrix&

matrix,osg::NodeVisitor* nv) const

{

osgUtil::CullVisitor* cv =

dynamic_cast(nv);

if (cv)

{

osg::Vec3 eyePointLocal = cv->getEyeLocal();

matrix.preMult(osg::Matrix::translate(eyePointLocal)); }

return true;

}

virtual bool computeWorldToLocalMatrix(osg::Matrix&

matrix,osg::NodeVisitor* nv) const

{

osgUtil::CullVisitor* cv =

dynamic_cast(nv);

if (cv)

{

osg::Vec3 eyePointLocal = cv->getEyeLocal();

matrix.postMult(osg::Matrix::translate(-eyePointLocal)); }

return true;

}

};

// Update texture matrix for cubemaps

struct TexMatCallback : public osg::NodeCallback

{

public:

TexMatCallback(osg::TexMat& tm) :

_texMat(tm)

{

}

virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)

{

osgUtil::CullVisitor* cv =

dynamic_cast(nv);

if (cv)

{

const osg::Matrix& MV = *(cv->getModelViewMatrix());

const osg::Matrix R =

osg::Matrix::rotate( osg::DegreesToRadians(112.0f), 0.0f,0.0f,1.0f)* osg::Matrix::rotate( osg::DegreesTo Radians(90.0f), 1.0f,0.0f,0.0f);

osg::Quat q = MV.getRotate();

const osg::Matrix C = osg::Matrix::rotate( q.inverse() );

_texMat.setMatrix( C*R );

}

traverse(node,nv);

}

osg::TexMat& _texMat;

};

//添加天空盒

//需要六张天空图片

osg::TextureCubeMap* CSkyLight::readCubeMap(std::string path)

{

osg::TextureCubeMap* cubemap = new osg::TextureCubeMap;

std::string fileName = path+"Front.bmp";

osg::Image* imagePosX = osgDB::readImageFile(fileName);

fileName = path+"Back.bmp";

osg::Image* imageNegX = osgDB::readImageFile(fileName);

fileName = path+"Right.bmp";

osg::Image* imagePosZ = osgDB::readImageFile(fileName);

fileName = path+"Left.bmp";

osg::Image* imageNegZ = osgDB::readImageFile(fileName);

fileName = path+"Down.bmp";

osg::Image* imagePosY = osgDB::readImageFile(fileName);

fileName = path+"Up.bmp";

osg::Image* imageNegY = osgDB::readImageFile(fileName);

if (imagePosX && imageNegX && imagePosY && imageNegY && imagePosZ && imageNegZ)

{

cubemap->setImage(osg::TextureCubeMap::POSITIVE_X, imagePosX); cubemap->setImage(osg::TextureCubeMap::NEGATIVE_X, imageNegX); cubemap->setImage(osg::TextureCubeMap::POSITIVE_Y, imagePosY); cubemap->setImage(osg::TextureCubeMap::NEGATIVE_Y, imageNegY); cubemap->setImage(osg::TextureCubeMap::POSITIVE_Z, imagePosZ); cubemap->setImage(osg::TextureCubeMap::NEGATIVE_Z, imageNegZ);

cubemap->setWrap(osg::Texture::WRAP_S,

osg::Texture::CLAMP_TO_EDGE);

cubemap->setWrap(osg::Texture::WRAP_T,

osg::Texture::CLAMP_TO_EDGE);

cubemap->setWrap(osg::Texture::WRAP_R,

osg::Texture::CLAMP_TO_EDGE);

cubemap->setFilter(osg::Texture::MIN_FILTER,

osg::Texture::LINEAR_MIPMAP_LINEAR);

cubemap->setFilter(osg::Texture::MAG_FILTER,

osg::Texture::LINEAR);

}

return cubemap;

}

osg::Node* CSkyLight::createSkyBox(std::string path)

{

osg::StateSet* stateset = new osg::StateSet();

osg::TexEnv* te = new osg::TexEnv;

te->setMode(osg::TexEnv::REPLACE);

stateset->setTextureAttributeAndModes(0, te,

osg::StateAttribute::ON);

osg::TexGen *tg = new osg::TexGen;

tg->setMode(osg::TexGen::NORMAL_MAP);

stateset->setTextureAttributeAndModes(0, tg,

osg::StateAttribute::ON);

osg::TexMat *tm = new osg::TexMat;

stateset->setTextureAttribute(0, tm);

osg::TextureCubeMap* skymap = readCubeMap(path);

stateset->setTextureAttributeAndModes(0, skymap,

osg::StateAttribute::ON);

stateset->setMode( GL_LIGHTING, osg::StateAttribute::OFF );

stateset->setMode( GL_CULL_FACE, osg::StateAttribute::OFF );

// clear the depth to the far plane.

osg::Depth* depth = new osg::Depth;

depth->setFunction(osg::Depth::ALWAYS);

depth->setRange(1.0,1.0);

stateset->setAttributeAndModes(depth, osg::StateAttribute::ON ); stateset->setRenderBinDetails(-1,"RenderBin");

osg::Drawable* drawable = new osg::ShapeDrawable(new

osg::Sphere(osg::Vec3(0.0f,0.0f,0.0f),1));

osg::Geode* geode = new osg::Geode;

geode->setCullingActive(false);

geode->setStateSet( stateset );

geode->addDrawable(drawable);

osg::Transform* transform = new MoveEarthySkyWithEyePointTransform; transform->setCullingActive(false);

transform->addChild(geode);

osg::ClearNode* clearNode = new osg::ClearNode;

clearNode->setCullCallback(new TexMatCallback(*tm));

clearNode->addChild(transform);

return clearNode; }