C++ randf函数代码示例

static void display(void)
{
	glClearColor(randf(), randf(), randf(), 1.0f);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glutSwapBuffers();
	glutPostRedisplay();
}

glm::mat4 randMat()
{
	float theta = randf(-PI / 2, PI / 2), phi = randf(0.0f, 2 * PI);
	glm::mat4 rotation = glm::rotate(glm::mat4(1.0), phi, glm::vec3(1.0, 0.0, 0.0));
	rotation = glm::rotate(rotation,     theta, glm::vec3(0.0, 1.0, 0.0));
	return rotation;
}

void Server::broadcastFaultyData(const char* data, unsigned int size) {
	packetNumber++;
	// lose messages every so often
	if (randf() * 100 < m_packetlossPercentage)
		return;

	// delay messages every so often
	if (randf() * 100 < m_delayPercentage) {
		DelayedBroadcast* b = new DelayedBroadcast;
		b->stream.Write((RakNet::MessageID)GameMessages::ID_ENTITY_LIST);
		b->stream.Write(size);
		b->stream.Write(packetNumber);
		b->stream.Write(data, size);
		float delay = randf() * m_delayRange;
		b->delayMicroseconds = (double)(delay * 1000.0 * 1000.0);
		m_delayedMessages.push_back(b);
	}
	else {
		// just send the stream
		RakNet::BitStream stream;
		stream.Write((RakNet::MessageID)GameMessages::ID_ENTITY_LIST); 
		stream.Write(size);
		stream.Write(packetNumber);
		stream.Write(data, size);
		sendBitStream(&stream);
	}
}

void FlowShower::update()
{
	scale += (scaleb - scale) * 0.1;
	if (game->isMiddleDown() && !painting)
	{
		viewX = pressViewX + (pressX - float(game->getMouseX())
				/ float(game->getResY())) / scale;
		viewY = pressViewY - (pressY - float(game->getMouseY())
				/ float(game->getResY())) / scale;
	}
	inkNew+=0.1f;
	while(inkNew>=1.0f)
	{
		inkNew-=1.0f;
		inkRed=inkRedNew;
		inkGreen=inkGreenNew;
		inkBlue=inkBlueNew;
		inkRedNew=randf(1.0f);
		inkGreenNew=randf(1.0f);
		inkBlueNew=randf(1.0f);
	}
	clock_t curentClock = clock();
	/*if (lastClock != 0 || dt != 0)
	 dt = float(curentClock - lastClock) / 1000.0f;*/
	lastClock = curentClock;

}

void Tile::Init(float roughness) {
  // Zufallsgenerator initialisieren
  srand(static_cast<unsigned int>(time(0)));

  // x- und z-Koordinaten berechnen.
  // Das Wurzel-Tile ersteckt sich entlang der x- und z-Achse immer im Bereich
  // [-2.5, 2.5]
  int i = 0;
  for (int y = 0; y < size_; ++y) {
    for (int x = 0; x < size_; ++x, ++i) {
      vertices_[i].x = x * 5.0f / (size_ - 1) - 2.5f;
      vertices_[i].z = y * 5.0f / (size_ - 1) - 2.5f;
    }
  }

  // Ecken mit Zufallshöhenwerten initialisieren
  int block_size = size_ - 1;
  vertices_[I(0, 0)].y = randf();
  vertices_[I(0, block_size)].y = randf();
  vertices_[I(block_size, 0)].y = randf();
  vertices_[I(block_size, block_size)].y = randf();

  // Verfeinerungsschritte durchführen bis sämtliche Werte berechnet sind
  while (block_size > 1) {
    Refine(block_size, roughness);
    block_size = block_size / 2;
  }
}

static inline float RandFloat(const float min, const float max) {
	// we work with large floats here (1e22 etc.) we cannot blend them without overflows, so do it a bit differently
	if (rand() & 1) {
		return max * randf();
	}
	return min * randf();
}

void metro(double *m, double *T) /*Metropolitan algorithm*/
{
 	int i, x, y, xdown, xup, ydown, yup, sum;
 	double deltaE;
 
 	for (i = 0; i < LX*LY; i++)
 	{
  		x = randf()*LX;	/* Choose a random coordinate in the lattice */
  		y = randf()*LY;
  
  		xup = (x + 1)%LX;		/*determine neighbor sites, with periodic BCs */
  		xdown = (x + LX - 1)%LX;
  		yup = (y + 1)%LY;
  		ydown = (y + LY - 1)%LY;
 
  /*compute the sum of the spins of sites neighboring coordinate*/
  		sum = spin[xdown][y] + spin[xup][y] + spin[x][yup] + spin[x][ydown];
  
  /*compute change in energy if spin is flipped at coordinate*/
  		deltaE = 2.0*J*spin[x][y]*sum/(*T);
  		if (randf() < exp(-deltaE)) /* decide if flip is accepted*/
  		{
   			*m -= 2.0*spin[x][y]/(LX*LY); /*flip spin and compute m*/
   			spin[x][y] *= -1;
  		}
 	}
}

void generateRandomPyrFrustums( int n,
								float minFOV, float maxFOV,
								float minNear, float maxNear,
								float minFar, float maxFar,
								float minAspectRatio, float maxAspectRatio,
								float minPosX, float maxPosX,
								float minPosY, float maxPosY,
								float minPosZ, float maxPosZ,
								float minRotX, float maxRotX,
								float minRotY, float maxRotY,
								float minRotZ, float maxRotZ,
								std::vector<glPyramidalFrustum>& list )
{
	for(int i = 0; i < n; ++i )
	{
		float FOV = minFOV + randf()*( maxFOV - minFOV );
		float Near = minNear + randf()*( maxNear - minNear );
		float Far = minFar + randf()*( maxFar - minFar );
		float AspectRatio = minAspectRatio + randf()*( maxAspectRatio - minAspectRatio );
		float PosX = minPosX + randf()*( maxPosX - minPosX );
		float PosY = minPosY + randf()*( maxPosY - minPosY );
		float PosZ = minPosZ + randf()*( maxPosZ - minPosZ );
		float RotX = minRotX + randf()*( maxRotX - minRotX );
		float RotY = minRotY + randf()*( maxRotY - minRotY );
		float RotZ = minRotZ + randf()*( maxRotZ - minRotZ );
		glPyramidalFrustum f(FOV, Near, Far, AspectRatio, glVector4f(PosX, PosY, PosZ, 0), RotX, RotY, RotZ );
		list.push_back( f );
	}
}

void cart_rnd_star(int id)
{
	float x = randf(2.0)-1.0;
	float y = randf(2.0)-1.0;
	stars[id][0] = sqrtf(x*x+y*y);
	stars[id][1] = atan2(y,x);
}

PowerUp::PowerUp(float x, float y, int type) :
   SPIN_SPEED(0.002f)
{
   this->x = x;
   this->y = y;
   this->type = type;

   dx = randf(0.5f, 1.2f);
   dy = randf(0.5f, 1.2f);
   radius = 16;
   isDestructable = false;
   hp = 1;

   da = (rand() % 2) ? -SPIN_SPEED : SPIN_SPEED;

   ResourceManager& rm = ResourceManager::getInstance();
   
   switch (type) {
      case POWERUP_LIFE:
         bitmap = (ALLEGRO_BITMAP *)rm.getData(RES_LIFEPOWERUP);
         break;
      default:
         type = POWERUP_WEAPON;
         bitmap = (ALLEGRO_BITMAP *)rm.getData(RES_WEAPONPOWERUP);
         break;
   }
}

//get trigger position/volume relative to sound rects for single grain voice
void GrainClusterVis::getTriggerPos(unsigned int idx, double * playPos, double * playVol,float theDur)
{
    bool trigger = false;
    SoundRect * theRect = NULL;
    if (idx < myGrainsV->size()){
        GrainVis * theGrain = myGrainsV->at(idx);
        //TODO: motion models
        //updateGrainPosition(idx,gcX + randf()*50.0 + randf()*(-50.0),gcY + randf()*50.0 + randf()*(-50.0));
        updateGrainPosition(idx,gcX + (randf()*xRandExtent - randf()*xRandExtent),gcY + (randf()*yRandExtent - randf()*yRandExtent));
        for (int i = 0; i < theLandscape->size(); i++) {
            theRect = theLandscape->at(i);
            bool tempTrig = false;
            tempTrig = theRect->getNormedPosition(playPos,playVol,theGrain->getX(),theGrain->getY(),i);
            if (tempTrig == true)
                trigger = true;
            // cout << "playvol: " << *playPos << ", playpos: " << *playVol << endl;
            
        }
        if (trigger == true){
            theGrain->trigger(theDur);
        }
    }
    
    
}

void setup(){

	map.init( 16, 14, 0.2 );

	printf( " %f \n", map.invStep );

/*
	Point2D* p = new Point2D( { 10.8, 13.9 } ); 
	printf( " p: %f %f \n",p->x,p->y );
	int ix,iy;
	map.boxIndex( p, ix, iy );
	printf( " ix,iy: %i %i \n",ix,iy );

*/

	for (int i=0; i<1000; i++){
		Point2D* p = new Point2D( { randf(0,2), randf(0,2) } );
		map.insert( p );
		//printf( " i:i0,ii,i0s[ii]  %i: %i %i %i \n", i, i0, ii, map.i0s[ii] );
	};

	map.makeStatic();


}

TestApp::TestApp( int& id, int WIDTH_, int HEIGHT_ ) : AppSDL2OGL( id, WIDTH_, HEIGHT_ ) {

    //int power = 8; int nside = 5;
    //int power = 11; int nside = 20;
    int power = 16; int nside = 300;
    //int power = 20; int nside = 400;
    //int power = 24; int nside = 1500;


	npoints = 4*nside*nside;
	points  = new Vec2d[npoints];
    map.init( 0.5f, power );
	printf( "map: %i %i %i %i \n", map.power, map.mask, map.capacity, map.filled );
	int i = 0;
	for( int iy=-nside+1; iy<nside; iy++ ){
		for( int ix=-nside+1; ix<nside; ix++ ){
			i++;
			points[ i ].set( ( ix + randf() ) * map.step, ( iy + randf() ) * map.step );
			//map.insertNoTest( &(points[i]), points[i].x, points[i].y  );
			map.insertIfNew( &(points[i]), points[i].x, points[i].y  );
			//printf( " insering (%i,%i) %i (%3.3f,%3.3f) \n", ix, iy, i, points[i].x, points[i].y );
		};
	};
	printf( "map: %i %i %i %i \n", map.power, map.mask, map.capacity, map.filled );

	hist.init( 20, 0, 20 );
	for( int i=0; i<map.capacity; i++ ){
		hist.insert( map.fields[i].n + 0.5 );
	}
	printf( "now comes printHistogram( hist );\n" );
	printHistogram( hist );
}

void random_points(point ps[], int count, double min, double max, bool integer)
{
	std::set<std::pair<int, int>> points_set;
	if (integer)
	{
		for (int i = 0; i < count; i++)
		{
			bool unique = true;
			int x, y;
			do
			{
				x = (int)round(min + (max - min) * randf());
				y = (int)round(min + (max - min) * randf());
				if (points_set.find(std::make_pair(x, y)) != points_set.end())
					unique = false;
			} while (!unique);
			ps[i] = point(x, y);
			points_set.insert(std::make_pair(x, y));
		}
	}
	else
	{
		for (int i = 0; i < count; i++)
			ps[i] = point(min + (max - min) * randf(), min + (max - min) * randf());
	}
}

Path SplineGenerator::makeBezier(int points, int nodes, int seed)
{
    srand(seed);
    Path path;
    int minDist = 0.35355;
    std::cout << "MinDist: " << minDist << std::endl;
    Vector2d start(randf(),0);
    Vector2d end(randf(),1);

    for (int node=0 ; node < nodes ; ++node)
    {

        Vector2d p0 = start;
        Vector2d p1(randf(), randf());
//        Vector2d p1(rand()%w,rand()%h);
        Vector2d p2(randf(), randf());
        Vector2d p3(randf(), randf());
        while(p3.getDistance(p1)<minDist)
        {
            p3.x = randf();
            p3.y = randf();
        }

        int pointsPerNode = points / nodes;
        for (int x=0; x<pointsPerNode;++x)
        {
            float t = x/float(pointsPerNode);
            Vector2d res= calculateBezierPoint(t,p0,p1,p2,p3);
            path.push_back(res);
        }

        start = p3;
    }

    //do last link
//    Vector2d p0 = start;
//    Vector2d p1(rand()%w,rand()%h);
//    Vector2d p2(rand()%w,rand()%h);
//    Vector2d p3 = end;
//    for (int x=0; x<steps;++x)
//    {
//        float t = x/float(steps);
//        Vector2d res= calculateBezierPoint(t,p0,p1,p2,p3);
//        if (x!=0)
//        {
//            out << t << "\t" << res.x <<"\t" << res.y << std::endl;
//        }
//        else
//        {
//            out << t << "\t" << res.x <<"\t" << res.y << "\t" << start.x << "\t" << start.y << std::endl;
//        }
//    }




    //end test for bezier curving
    return path;
}