C++ Ray::calcPosition方法代码示例

vec3 Sphere::closestPoint( const Ray &ray ) const
{
	float 		t;
	vec3		diff 	= ray.getOrigin() - mCenter;
	float 		a 		= dot( ray.getDirection(), ray.getDirection() );
	float 		b 		= 2 * dot( diff, ray.getDirection() );
	float 		c 		= dot( diff, diff ) - mRadius * mRadius;
	float 		disc	= b * b - 4 * a * c;

	if( disc > 0 ) {
		float e = math<float>::sqrt( disc );
		float denom = 2 * a;
		t = (-b - e) / denom;    // smaller root

		if( t > EPSILON_VALUE )
			return ray.calcPosition( t );

		t = (-b + e) / denom;    // larger root
		if( t > EPSILON_VALUE )
			return ray.calcPosition( t );
	}
	
	// doesn't intersect; closest point on line
	t = dot( -diff, normalize(ray.getDirection()) );
	vec3 onRay = ray.calcPosition( t );
	return mCenter + normalize( onRay - mCenter ) * mRadius;
	
//	return ray.getDirection() * dot( ray.getDirection(), (mCenter - ray.getOrigin() ) );
}

float RayMarcher::marchSecondary( const Ray &ray )
{
	const float RAY_EPSILON = 0.50f;
	float boxTimes[2];
	if( mBoundingBox.intersect( ray, boxTimes ) != 2 )
		return 0;
		
	Vec3f pointOfDeparture;
	if( boxTimes[0] >= 0 )
		pointOfDeparture = ray.calcPosition( boxTimes[0] );
	else
		pointOfDeparture = ray.calcPosition( boxTimes[1] );
	float span = ray.getOrigin().distance( pointOfDeparture );
	int numSteps = (int)( span / RAY_EPSILON );
	if( numSteps <= 0 ) 
		return 0;

	Vec3f step( ray.getDirection() );
	step *= RAY_EPSILON;

	Vec3f rayPos = ray.getOrigin(); 

	float result = 0;
	for( int i = 0; i < numSteps; ++i ) {
		float D = sampleDensity( rayPos ) * RAY_EPSILON;
		result += D * ( 1.0f - result );
		
		rayPos += step; 
	}

	return result;
}

ColorA RayMarcher::march( const Ray &ray )
{
	const float RAY_EPSILON = 0.25f;
	float boxTimes[2];
	if( mBoundingBox.intersect( ray, boxTimes ) < 2 )
		return ColorA::zero();

	Vec3f pos0, pos1;
	if( boxTimes[0] < boxTimes[1] ) {
		pos0 = ray.calcPosition( boxTimes[0] );
		pos1 = ray.calcPosition( boxTimes[1] );	
	}
	else {
		pos0 = ray.calcPosition( boxTimes[1] );
		pos1 = ray.calcPosition( boxTimes[0] );		
	}

	float span = pos0.distance( pos1 );
	int numSteps = (int)( span / RAY_EPSILON );
	if( numSteps <= 0 ) 
		return ColorA::zero();

	Vec3f step( ray.getDirection() );
	step *= RAY_EPSILON;

	Vec3f rayPos = pos0; 
	Vec3f lightVec = mCamera->getModelViewMatrix().transformVec( Vec3f( 1, 1, 1 ).normalized() );
	float transparency = 1.0f;
	ColorA result = ColorA::zero();
	for( int i = 0; i < numSteps; ++i ) {
		ColorA sample;
		float D = sampleDensity( rayPos ) * RAY_EPSILON;
		if( D >= 0.001f ) {
			sample.a = D;
			float t = sample.a * ( 1.0f - result.a );
			const float ambient = 0.45f;
			const float diffuse = 1.0f - ambient;
			float c = ambient + diffuse * ( 1.0f - marchSecondary( Ray( rayPos, lightVec ) ) );
			result += ColorA( c * t, c * t, c * t, t );

			if( transparency < 0.001f )
				break;
		}
		
		rayPos += step; 
	}

	if( result.r < 0 ) result.r = 0;
	if( result.r > 1 ) result.r = 1;
	if( result.g < 0 ) result.g = 0;
	if( result.g > 1 ) result.g = 1;	
	if( result.b < 0 ) result.b = 0;
	if( result.b > 1 ) result.b = 1;	
	return result;
}

void RodSoundApp::mouseDown(MouseEvent event)
{
  if (event.isRight()) {
    // Set targetPos to the ControlPoint we just clicked
    if (!r) return;
    Vec2i mouse = event.getPos();
    Vec2i windowSize = getWindowSize();
    Ray ray = cam.generateRay((real)mouse.x/windowSize.x,
                            1.0 - (real)mouse.y/windowSize.y,
                            getWindowAspectRatio());
    real tmin = INFINITY;
    bool any = false;
    for (int i=0; i<r->numCPs(); i++) { // A bit slow, but beats keeping a KD-Tree updated
      Sphere s(EtoC(r->cur().POS(i)), constants::radius * 1.5);
      float t;
      if (s.intersect(ray, &t) && t < tmin) {
        any = true;
        tmin = t;
      }
    }
    if (!any) return;
    targetPos = ray.calcPosition(tmin);
    cam.lookAt(targetPos);
  } else {
    if (!running) return;
    isMouseDown = true;
    mouseDrag(event);
  }
}

void gpuPSApp::computeAttractorPosition()
{
    // The attractor is positioned at the intersection of a ray
    // from the mouse to a plane perpendicular to the camera.
    float t = 0;
    Vec3f right, up;
    mMayaCam.getCamera().getBillboardVectors(&right, &up);
    CameraPersp cam = mMayaCam.getCamera();
    float u = mMousePos.x / (float) getWindowWidth();
    float v = mMousePos.y / (float) getWindowHeight();
    Ray ray = cam.generateRay(u , 1.0f - v, cam.getAspectRatio() );
    if (ray.calcPlaneIntersection(Vec3f(0.0f,0.0f,0.0f), right.cross(up), &t)) {
        mAttractor.set(ray.calcPosition(t));
    }
}

void RodSoundApp::mouseDrag(MouseEvent event)
{
  if (!running) return;
  Vec2i mouse = event.getPos();
  Vec2i windowSize = getWindowSize();
  
  Ray r = cam.generateRay((real)mouse.x/windowSize.x,
                          1.0 - (real)mouse.y/windowSize.y,
                          getWindowAspectRatio());
  
  float t;
  if(!r.calcPlaneIntersection(targetPos, targetPos-eyePos, &t)) {
    std::cerr << "Mouse ray did not intersect plane!\n";
  }
  mousePosition = r.calcPosition(t);
}

//------------------------------------------------------------------------------
bool
SceEllipsoid::RayCast(Ray const & ray, 
                      float & t, 
                      Vec3f & point, 
                      Vec3f & normal) const
{
    float tIntersection;

    if (RayCast(ray, tIntersection))
    {
        t = tIntersection;
        point = ray.calcPosition(tIntersection);
        normal = (mMatrixInvTInv * (point - mCenter)).normalized();
        return true;
    }

    return false;
}