// Extremely Fast Line Algorithm Var D (Addition Fixed Point)
// Copyright 2001, By Po-Han Lin


// Freely useable in non-commercial applications as long as 
// credits to Po-Han Lin and link to http://www.edepot.com is 
// provided in source code and can been seen in compiled executable.  
// Commercial applications please inquire about licensing the algorithms.
//
// Lastest version at http://www.edepot.com/phl.html

// used by myLine
void myPixel(SURFACE* surface, int x,int y) {
	// PLOT x,y point on surface

}


// THE EXTREMELY FAST LINE ALGORITHM Variation D (Addition Fixed Point)
void myLine(SURFACE* surface, int x, int y, int x2, int y2) {
	bool yLonger=false;
	int incrementVal, endVal;
	int shortLen=y2-y;
	int longLen=x2-x;
	if (abs(shortLen)>abs(longLen)) {
		int swap=shortLen;
		shortLen=longLen;
		longLen=swap;
		yLonger=true;
	}
	endVal=longLen;
	if (longLen<0) {
		incrementVal=-1;
		longLen=-longLen;
	} else incrementVal=1;
	int decInc;
	if (longLen==0) decInc=0;
	else decInc = (shortLen << 16) / longLen;
	int j=0;
	if (yLonger) {	
		for (int i=0;i!=endVal;i+=incrementVal) {
			myPixel(surface,x+(j >> 16),y+i);	
			j+=decInc;
		}
	} else {
		for (int i=0;i!=endVal;i+=incrementVal) {
			myPixel(surface,x+i,y+(j >> 16));
			j+=decInc;
		}
	}


}

void mySquare(SURFACE* surface,int x, int y, int x2, int y2) {
	myLine(surface,x,y,x2,y2);
	myLine(surface,x2,y2,x2+(y-y2),y2+(x2-x));
	myLine(surface,x,y,x+(y-y2),y+(x2-x));
	myLine(surface,x+(y-y2),y+(x2-x),x2+(y-y2),y2+(x2-x));
}


void myRect(SURFACE* surface, int x, int y, int x2, int y2) {
	myLine(surface,x,y,x2,y);
	myLine(surface,x2,y,x2,y2);
	myLine(surface,x2,y2,x,y2);
	myLine(surface,x,y2,x,y);
}