/* Filename: BasicLineBounce.cpp
 *
 * Author: Br. David Carlson
 *
 * Date: July 6, 2009
 *
 * Description:  This GDK program bounces a vertical lightray off the walls of the window.
 * A sound is made at each bounce off a wall. The user can press the ESC key to exit.
 */
#include "DarkGDK.h"

const int START = 0;
const int NORMAL = 1;
const int INCOMING = 2;
const int OUTGOING = 3;

const DWORD black = dbRGB(0, 0, 0);
const DWORD cyan = dbRGB(0, 250, 250);

// Main function:
void DarkGDK()
{
	int CenterX, MinY, MaxY, FrontY, RearY, WallY, State, DeltaY, Count;
	const int RayLength = 99;  // Must be odd.

	dbSetWindowTitle("Vertical Light Ray");
	CenterX = dbScreenWidth() / 2;
	MinY = 0;
	MaxY = dbScreenHeight() - 1;
	dbInk(cyan, black);
	dbLoadSound("cowbell.wav", 1);  // Sound file must be in the current directory for this to work.

	dbSyncOn();
	dbSyncRate(1000);

	State = START;
	FrontY = MaxY;  // Points to the next spot to color in for the lightray.
	RearY = MaxY;  // Points to the last spot to color in for the lightray.
	Count = 1;
	DeltaY = -1;

	while (LoopGDK())
	{
	   dbCLS();   // Clear the screen.

		if (State == START)
		{
			dbLine(CenterX, RearY, CenterX, FrontY);
			Count++;
			FrontY += DeltaY;
			if (Count == RayLength)
			   State = NORMAL;
		}
		else if (State == NORMAL)
		{
			dbLine(CenterX, RearY, CenterX, FrontY);
			FrontY += DeltaY;
			RearY += DeltaY;
			if (FrontY == MinY)
			{
				State = INCOMING;
				DeltaY = 1;
				WallY = MinY;
				dbPlaySound(1);
			}
			else if (FrontY == MaxY)
			{
				State = INCOMING;
				DeltaY = -1;
				WallY = MaxY;
				dbPlaySound(1);
			}
		}
		else if (State == INCOMING)
		{
			dbLine(CenterX, RearY, CenterX, WallY);
			FrontY += DeltaY;
			RearY -= DeltaY;
			if (FrontY == RearY)
			   State = OUTGOING;
		}
		else if (State == OUTGOING)
		{
			dbLine(CenterX, WallY, CenterX, FrontY);		
			FrontY += DeltaY;
			RearY -= DeltaY;
			if ((RearY == MinY) || (RearY == MaxY))
			   State = NORMAL;
		}

		dbSync();
	}
}