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光线追踪

2024-07-05 10:13:32   226人阅读

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#include <osgViewer/Viewer>
#include <osgDB/WriteFile>
const int GRID_WIDTH = 1024;
const int GRID_HEIGHT = 800;
#pragma comment(lib, "osgd.lib")
#pragma comment(lib, "osgViewerd.lib")
#pragma comment(lib, "osgDBd.lib")
class CRay
{
public:
    CRay(osg::Vec3 orgin, osg::Vec3 direction)
        :_orgin(orgin)
        ,_direction(direction)
    {
         
    }
 
    osg::Vec3 GetOrgin()
    {
        return _orgin;
    }
     
    void SetOrgin(osg::Vec3 orgin)
    {
        _orgin = orgin;
    }
 
    osg::Vec3 GetDirection()
    {
        return _direction;
    }
     
    void SetDirection(osg::Vec3 dir)
    {
        _direction = dir;
    }
 
    osg::Vec3 GetPoint(float t)
 
    {
        return _orgin + _direction * t;
    }
 
private:
    osg::Vec3 _orgin;
    osg::Vec3 _direction;
    float     _t;
};
 
class CIntersectResult
{
public:
    CIntersectResult()
        :_isHit(false)
    {
             
    }
    static CIntersectResult NoHit()
    {
        return CIntersectResult();
    }
public:
    bool        _isHit;
    float       _distance;
    osg::Vec3   _position;
    osg::Vec3   _normal;
};
 
class CGeometry
{
public:
    CGeometry()
    {
 
    }
    virtual CIntersectResult IsIntersect(CRay ray) = 0;
};
 
 
class CSphere : public CGeometry
{
public:
    CSphere()
        :CGeometry()
    {
 
    }
    CSphere(osg::Vec3 center, double radius)
        :CGeometry()
        ,_center(center)
        ,_radius(radius)
    {
 
    }
    CSphere(CSphere & s)
    {
        _center = s.GetCenter();
        _radius = s.GetRadius();
    }
 
    void SetCenter(osg::Vec3 & center)
    {
        _center = center;  
    }
    void SetRadius(float radius)
    {
        _radius = radius;
    }
 
    osg::Vec3 GetCenter()
    {
        return _center;
    }
 
    float GetRadius()
    {
        return _radius;
    }
 
    osg::Vec3 GetNormal(osg::Vec3 p)
    {
        return p - _center;
    }
 
    virtual CIntersectResult IsIntersect(CRay ray)
    {
        CIntersectResult result = CIntersectResult::NoHit();
        osg::Vec3 v = ray.GetOrgin() - _center;
        float a0 = v * v - _radius * _radius;
        float dir_dot_v = ray.GetDirection() * v;
 
        if (dir_dot_v < 0)
        {
            float discr = dir_dot_v * dir_dot_v - a0;
            if (discr >= 0)
            {
                result._isHit = true;
                result._distance = -dir_dot_v - std::sqrt(discr);
                result._position = ray.GetPoint(result._distance);
                result._normal = result._position - _center;
                result._normal.normalize();
            }
        }
        return result;
    }
 
private:
    osg::Vec3 _center;
    float     _radius;
};
 
class CPerspectiveCamera
{
public:
    CPerspectiveCamera()
    {
         
    }
    ~CPerspectiveCamera()
    {
 
    }
    CPerspectiveCamera(const osg::Vec3 & eye, const osg::Vec3 & front, const osg::Vec3 & refUp, float fov)
    {
        _eye = eye;
        _front = front;
        _refUp = refUp;
        _fov = fov;
        _right = _front ^ _refUp;
        _up = _right ^ _front;
        _fovScale = std::tan(fov * osg::PI * 0.5 / 180.0) * 2.0;
    }
    CRay GenerateRay(float x, float y)
    {
        osg::Vec3 r = _right * ((x - 0.5f) * _fovScale);
        osg::Vec3 u = _up * ((y - 0.5f) * _fovScale);
        osg::Vec3 temp = _front + r + u;
        temp.normalize();
        return CRay(_eye, temp);
    }
private:
    osg::Vec3 _eye;
    osg::Vec3 _front;
    osg::Vec3 _refUp;
    float     _fov;
    osg::Vec3 _right;
    osg::Vec3 _up;
    float     _fovScale;
};
 
osg::ref_ptr<osg::Image> CreateImage()
{
    osg::ref_ptr<osg::Image> image = new osg::Image;
    image->allocateImage(1024, 800, 1, GL_RGBA, GL_UNSIGNED_BYTE);
    unsigned char * data = http://www.mamicode.com/image->data();
    CPerspectiveCamera camera(osg::Vec3(0.0, 10.0, 10), osg::Vec3(0.0, 0.0, -1.0), osg::Vec3(0.0, 1.0, 0.0), 90);
    float depth = 7.0;
    float maxDepth = 18.0;
    CSphere sphere(osg::Vec3(0.0, 10, -10.0), 10.0);
    float dx = 1.0f/GRID_WIDTH;
    float dy = 1.0f/GRID_HEIGHT;
    float dDepth = 255.0f/maxDepth;
    int i = 0;
    for (int y = 0; y < GRID_HEIGHT; ++y)
    {
        float sy = 1 - dy * y;
        for (int x = 0; x < GRID_WIDTH; ++x)
        {
            float sx = dx * x;
            CRay ray(camera.GenerateRay(sx, sy));
            CIntersectResult result = sphere.IsIntersect(ray);
            if (result._isHit)
            {
                float t = std::min(result._distance * dDepth, 255.0f);
                int depth = (int)(255 - t);
                data[i] = depth;
                data[i+1] = depth;
                data[i+2] = depth;
                data[i+3] = 255;
            }
            i += 4;
        }
    }
    return image.get();
}
 
int main()
{
    osg::ref_ptr<osg::Image> image = CreateImage();
    osgDB::writeImageFile(*image.get(), "H:/1.png");
    return 0;
}

 

 


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