// ■地形生成（より単純なアルゴリズム）
//   左クリックのたびに地形を生成します。
#include "myWin.h"
#include "math.h"
#include "stdlib.h"
#include "time.h"
#define MX 512
#define frand() ((double) rand()/(double)(RAND_MAX+1))
static HDC hBuff; static HBITMAP hBM;
double map[MX+1][MX+1];
void setMap(int L, int U, int W, double dH){
	if(W<2)return;
	int WW = W / 2;
	map[L+WW][U+WW] = (map[L][U]+map[L+W][U]+map[L][U+W]+map[L+W][U+WW])*0.25
							+dH*(frand()-0.5);
	setMap(L   ,U   ,WW,dH);
    setMap(L+WW,U   ,WW,dH);
	setMap(L   ,U+WW,WW,dH);
	setMap(L+WW,U+WW,WW,dH);
}
void addFunc(){
	for(int i=0;i<MX+1;i++){
		double ii=(double)(i-MX/4)/(double)MX;double Di=ii*ii;
		for(int j=0;j<MX+1;j++){
			double jj= (double)(j-MX/4)/(double)MX; double Dj=jj*jj;
			double dH=exp(-sqrt(Di+Dj)/5)*10;
			map[i][j] +=dH;
		}
	}
}
void setMap(){
	setMap(0,0, MX,10);
	for(int k=0;k<50;k++)
	for(int i=1;i<MX;i++){
		for(int j=1;j<MX;j++){
			map[i][j]=(	map[i-1][j-1]+map[i-1][j]+map[i-1][j+1]+
						map[i  ][j-1]+map[i  ][j]+map[i+1][j  ]+
					    map[i+1][j-1]+map[i+1][j]+map[i+1][j+1])/9;
		}
	}
}
double minZ(){
	double R=map[0][0];
	for(int i=1;i<MX;i++) for(int j=0;j<MX;j++)if(map[i][j]<R) R=map[i][j];
	return R;
}
double maxZ(){
	double R=map[0][0];
	for(int i=1;i<MX;i++) for(int j=0;j<MX;j++)if(map[i][j]>R) R=map[i][j];
	return R;
}
void draw(){
	double V1=minZ(), V2=maxZ(); if(abs(V2-V1)<0.000001) V2=V1+1;
	double DD=(V2-V1)/768;int C;
	for(int i=1;i<MX;i++)for(int j=1;j<MX;j++){
		int ID=(int)((map[i][j]-V1)/DD);
		if     (ID<256) C = RGB(0     , ID    ,0);
		else if(ID<512) C = RGB(ID-256, 255   ,0);
		else if(ID<768) C = RGB(255   , 767-ID,0);
		else            C = RGB(255   , 0     ,0);
		SetPixel(hBuff,i+20, j+20, C);	
	}
}
void procPaint(HWND hw, WPARAM wp,LPARAM lp){
	PAINTSTRUCT ps;	HDC hdc=BeginPaint(hw, &ps);
	BitBlt(hdc, 0,0,260,260,hBuff,0,0,SRCCOPY);
	EndPaint(hw,&ps);
}
void procLButtonDown(HWND hw, WPARAM wp,LPARAM lp){
	setMap(); draw();
	InvalidateRect(hw,NULL,FALSE);
}
void procRButtonDown(HWND hw, WPARAM wp,LPARAM lp){
	addFunc();draw();
	InvalidateRect(hw,NULL,FALSE);
}
void procCreate(HWND hw, WPARAM wp,LPARAM lp){
	SetWindowText(hw,TEXT("仮想的な地形生成"));
	MoveWindow(hw,0,0,300,320,TRUE);
	HDC hdc=GetDC(hw); hBM=CreateCompatibleBitmap(hdc,260,260);
	hBuff=CreateCompatibleDC(hdc); SelectObject(hBuff,hBM);
	SelectObject(hBuff,GetStockObject(NULL_PEN));
	PatBlt(hBuff,0, 0,260,260,WHITENESS);
	ReleaseDC(hw,hdc);
	srand((unsigned int)time(NULL));
	for(int i=0;i<=MX;i++)
		for(int j=0;j<=MX;j++) map[i][j]=100;
	 procLButtonDown(hw, wp,lp);
}

LRESULT CALLBACK WndProc(HWND hw, UINT msg, WPARAM wp,LPARAM lp){
	switch(msg){
	case WM_DESTROY       : PostQuitMessage(0)         ; return 0;
	case WM_CREATE        : procCreate(hw,wp,lp)       ; return 0;
	case WM_PAINT         : procPaint(hw,wp,lp)        ; return 0;
	case WM_LBUTTONDOWN   : procLButtonDown(hw,wp,lp)  ; break;
	case WM_RBUTTONDOWN   : procRButtonDown(hw,wp,lp)  ; break;
	}
	return DefWindowProc(hw,msg,wp,lp);
}