//Surfing on sine waves
//(C) Haruka Kataoka 2004

WaveBuf wb;
Surfer sf;
int surfX = 20;//サーファーの位置
int vx = 1;//ループごとに波を進める量

void setup() 
{ 
  size(200, 200); 
  wb = new WaveBuf(100, 100, 2);
  sf = new Surfer(wb.peek(surfX), surfX, 2);
  stroke(255,255,255);
  framerate(60);
} 
 
void loop() 
{ 
  background(0,0,0); 
  wb.forward(vx);
  sf.move(vx, wb.peek(surfX), wb.peekv(surfX));
  int dispY = sf.height();
  wb.display(100-dispY);
  sf.display(100-dispY);
} 

//class Wave buffer
class WaveBuf
{ 
	float buf[];
	int bufSize; //バッファサイズ
	int rightBound, leftBound;//バッファ内の波の左右の境界位置
	int displayRange;
	int resolution;//解像度

	//波を発生する振動子の速度と、速度に影響する定数
	//speed -= kst * 振幅;
	float speed=5.0, kst=0.1;
	//波の状態を保持する長さ
	int duration;
	
	//Constructor
	//aSize:  wave bufferの大きさ
	//aResolution: 表示解像度
	WaveBuf(int aSize, int aDispRange, int aResolution) {
		buf = new float[aSize];
		bufSize = aSize;
		displayRange = aDispRange;
		resolution = aResolution;
		leftBound = 0;
		rightBound = aDispRange - 1;
		resetParameter(0);
		fillData_(leftBound, rightBound, -speed);
                duration = 200;
	}
	
	//kst, speedを再設定して波の状態を変える
	void resetParameter(float x) {
		float a = random(10.0, 100.0);//次の最大振幅
		float v = random(0.2, 5.0);//次の最大速度
		kst = (v*v) / (a*a);
		float t = 2*a*a - x*x;
		if (t > 0.0) {
			speed = ((speed>0.0)? 1: -1) * sqrt(kst*t);
		}else{
			speed = 0.0;
		}
	}
	
	//buf[from..to] の中の波データを埋める
	void fillData(int from, int to) {
		if (from <= to) {
			if (from == 0) {
				fillData_(from, to, buf[bufSize-1]);
			}else{
				fillData_(from, to, buf[from-1]);
			}
		}else{
			fillData_(from, bufSize-1, buf[from-1]);
			fillData_(   0,        to, buf[bufSize-1]);
		}
	}
	void fillData_(int from, int to, float preData) {
		for (int i=from; i<=to; i++){
			preData += speed;
			buf[i] = preData;
			speed += - kst * preData;
			if (--duration <= 0) {
				duration = int(random(bufSize/2, bufSize*2));
				resetParameter((float)preData);
			}
		}
	}
	
	//波を val 進める
	void forward(int val) {
		int reFillStart = rightBound + 1;
		if (reFillStart >= bufSize) reFillStart -= bufSize;
		rightBound += val;
		if (rightBound >= bufSize) rightBound -= bufSize;
		leftBound += val;
		if (leftBound >= bufSize) leftBound -= bufSize;
		fillData(reFillStart, rightBound);
	} 
	
	//表示
	void display(int zeroY) {
		if (leftBound <= rightBound) {
			display_(leftBound, rightBound, 0, zeroY);
		}else{
			int x = display_(leftBound,  bufSize-1, 0, zeroY);
			line( x,            zeroY + buf[bufSize-1], 
			      x+resolution, zeroY + buf[0]);
			x += resolution;
			        display_(        0, rightBound, x, zeroY);
		}
	}
	int display_(int from, int to, int x, int y) {
		for(int i=from; i<to; i++){
			line( x,            y + buf[i], 
			      x+resolution, y + buf[i+1]);
			x += resolution;
		}
		return x;
	}
	
	//位置 x の波の高さを返す
	//x: leftBoundからの位置
	float peek(int x) {
		x = leftBound + x;
		if (x >= bufSize) x -= bufSize;
		return buf[x];
	}
	//位置 x の波の傾きを返す
	//x: leftBoundからの位置
	float peekv(int x) {
		int f, b;
		f = leftBound + x + 1;
		b = leftBound + x - 1;
		if (f >= bufSize) f -= bufSize;
		if (b >= bufSize) b -= bufSize;
		return (buf[f] - buf[b]) / 2.0;
	}
} 


class Surfer {
	float height; //サーファーの高さ
	float vy;     //Y方向の速度
	float g=0.2;  //重力(vyを増加させる)
	float r=0.04; //空気抵抗(vyの大きさを規制する)
	int x, resolution;//X 位置, 解像度
	
	//Constractor
	//aHeight: サーファーの初期高さ
	//aX: サーファーの位置 (WaveBuffer での leftBoundからの位置)
	//aResolution: 表示解像度
	Surfer(float aHeight, int aX, int aResolution) {
		height = aHeight;
		vy = 0.0;
		x = aX*aResolution;
		resolution = aResolution;
	}
	
	//dX サーファーを進める
	//aHeight, wbv : 進んだ先の波の高さと傾き
	void move(int dX, float aHeight, float wbv) {
		height += vy * dX;
		if (height > aHeight) {
			vy = wbv;
			height = aHeight;
		}else{
			vy = vy + g - r*vy;
		}
	}
	
	//表示
	void display(int zeroY) {
		float rad = atan2(-vy, 1);
		int cs = (int)(resolution*2*cos(rad));
		int sn = (int)(resolution*2*sin(rad));
		//board
		int lx, ly, rx, ry;
		lx = x - cs;
		ly = zeroY+(int)height + sn;
		rx = x + cs;
		ry = zeroY+(int)height - sn;
		line(lx, ly, rx, ry);
		//legs
		int ax, ay;
		ax = x - (int)(resolution * rad);
		ay = zeroY+(int)height - resolution*4;
		line(lx, ly, ax, ay);
		line(rx, ry, ax, ay);
		//body
		int ny = ay - resolution*3;
		line(ax, ay, x, ny);
		//head
		line(x,  ny, x, ny - resolution);
		//arms
		line(x, ny, x-cs*2, ny + resolution*2);
		line(x, ny, x+cs*2, ny + resolution*2);
	}
	
	//サーファーの高さを返す
	int height() {
		return (int)height;
	}
}