Outward Spiral Algorithm

[Govind]

This is very old code of mine that I've recently found after backing up stuff off my old computer. Added some comments to it; thought I'd post it here.

#include <windows.h>
#define D_RIGHT 0
#define D_UP 1
#define D_LEFT 2
#define D_DOWN 3
typedef int DIRECTION;

void WindowSpiral(HWND hWnd, int jumpdiv)
{
	/* Declarations */
	RECT dimensions;  
	int centerX, centerY, jumps = 1, i, curX, curY, xjumpamt, yjumpamt;
	DIRECTION direction = D_RIGHT; 
	POINT p;

	/* Get the rect for dimension and jump configuration */
	GetWindowRect(hWnd,&dimensions);
	/* Integer division but at most we'd be off by one pixel; gets the center of the window */
	centerX = dimensions.left+((dimensions.right-dimensions.left)/2); 
	centerY = dimensions.top+((dimensions.bottom-dimensions.top)/2);
	/* These will be the amount jumped each iteration; integer division but good enough */
	xjumpamt = (dimensions.right-dimensions.left)/jumpdiv;
	yjumpamt = (dimensions.bottom-dimensions.top)/jumpdiv;

	/* Get into the middle of the window before we start */
	curX = centerX; curY = centerY;
	SetCursorPos(curX,curY);
	while(1)
	{
		//if(direction < 3) direction = D_RIGHT;
		for(i = 0; i < jumps; i++) 
		{
			switch(direction%4)
			{
				case D_RIGHT:
					curX+=xjumpamt;
					break;
				case D_UP:
					curY-=yjumpamt;
					break;
				case D_LEFT:
					curX-=xjumpamt;
					break;
				case D_DOWN:
					curY+=yjumpamt;
					break;
			}
			SetCursorPos(curX,curY);
			Sleep(50);
			// The above two lines are NOT necessary; they are only so you can see the current location of the spiral loop.
		}
		jumps++; direction++; // increment jumps and direction each time around so that the spiral will grow outward

		/* Check if we're out of the window rect; if so, no more*/
		GetCursorPos(&p);
		if(p.x >= dimensions.right) break;
		if(p.y >= dimensions.bottom) break;
		if(p.x <= dimensions.left) break;
		if(p.y <= dimensions.top) break;

	}	
}

From here, you can add GetPixel and change the return type to make a color clicker.

The SetCursorPos/GetCursorPos and Sleep lines shouldn't be in a finished application; those are there so the cursor can be used to indicate the path of the spiral. To check if you're finished in an application without those lines, compare curX/curY with the dimension.top/bottom/left/right values.

 

[blindkilla]

Thanks for sharing, SMR!

 

[Aeropsia]

I <3 you SMR!

 

[Govind]

Haha, thanks