OSG 天空盒子

OSG 天空盒子

這裏借用osgCookbook中的一個例子 。效果圖如下

#pragma once

#include <osg/TextureCubeMap>
#include <osg/Transform>


class SkyBox : public osg::Transform
{
public:
    SkyBox();

    SkyBox(const SkyBox &copy, osg::CopyOp copyop=osg::CopyOp::SHALLOW_COPY)
        : osg::Transform(copy, copyop){}

    META_Node(osg, SkyBox);

    void setEnvironmentMap( unsigned int unit, osg::Image* posX, osg::Image* negX,
        osg::Image* posY, osg::Image* negY, osg::Image* posZ, osg::Image* negZ );

    virtual bool computeLocalToWorldMatrix(osg::Matrix& matrix,osg::NodeVisitor*) const;
    virtual bool computeWorldToLocalMatrix(osg::Matrix& matrix,osg::NodeVisitor*) const;

protected:
    virtual ~SkyBox() {}

};


#include "skyBox.h"
#include <osg/Depth>
#include <osgUtil/CullVisitor>


SkyBox::SkyBox()
{
    setReferenceFrame(osg::Transform::ABSOLUTE_RF);
    setCullingActive(false);

    osg::StateSet *ss = getOrCreateStateSet();
    ss->setAttributeAndModes(new osg::Depth(osg::Depth::LEQUAL, 1.0f, 1.0f));
    ss->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
    ss->setMode(GL_CULL_FACE, osg::StateAttribute::OFF);
    ss->setRenderBinDetails(5, "RenderBin");
}

void SkyBox::setEnvironmentMap(unsigned int unit, osg::Image *posX, osg::Image* negX, osg::Image* posY, osg::Image* negY, osg::Image* posZ, osg::Image* negZ )
{
    if ( posX && posY && posZ && negX && negY && negZ )
    {
        osg::ref_ptr<osg::TextureCubeMap> cubemap = new osg::TextureCubeMap;
        cubemap->setImage( osg::TextureCubeMap::POSITIVE_X, posX );
        cubemap->setImage( osg::TextureCubeMap::NEGATIVE_X, negX );
        cubemap->setImage( osg::TextureCubeMap::POSITIVE_Y, posY );
        cubemap->setImage( osg::TextureCubeMap::NEGATIVE_Y, negY );
        cubemap->setImage( osg::TextureCubeMap::POSITIVE_Z, posZ );
        cubemap->setImage( osg::TextureCubeMap::NEGATIVE_Z, negZ );

        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 );
        cubemap->setResizeNonPowerOfTwoHint( false );
        getOrCreateStateSet()->setTextureAttributeAndModes( unit, cubemap.get() );
    }
}

/*  在渲染遍歷節點中( rendering Traveral() )，會進行裁剪,裁剪函數中會調用computeLocalToWorldMatrix  */
bool SkyBox::computeLocalToWorldMatrix( osg::Matrix& matrix, osg::NodeVisitor* nv ) const
{
    if ( nv && nv->getVisitorType()==osg::NodeVisitor::CULL_VISITOR )        
    {
        osgUtil::CullVisitor* cv = static_cast<osgUtil::CullVisitor*>( nv );
        //skeBox 隨相機移動
        matrix.preMult( osg::Matrix::translate(cv->getEyeLocal()) );
        return true;
    }
    else
        return osg::Transform::computeLocalToWorldMatrix( matrix, nv );
}

bool SkyBox::computeWorldToLocalMatrix( osg::Matrix& matrix, osg::NodeVisitor* nv ) const
{
    if ( nv && nv->getVisitorType()==osg::NodeVisitor::CULL_VISITOR )
    {
        osgUtil::CullVisitor* cv = static_cast<osgUtil::CullVisitor*>( nv );
        matrix.postMult( osg::Matrix::translate(-cv->getEyeLocal()) );
        return true;
    }
    else
        return osg::Transform::computeWorldToLocalMatrix( matrix, nv );
}