// splash.js

// home page animation for sparkplug.ca

// Javascript by Gordon Hicks, Gherkin Works <hicks@gherkin.com>, (C) copyright 2005, all rights reserved



	// Global vars
	
		// persona dramatis
		var spritePlugA ;
		var spritePlugB ;
		var spriteSparks ;
		var spriteExplosion ;
		var spriteBigEyes ;
		var buttonBoost ;
		var staticNav ;
		var staticLogo ;
		var staticFooter ;
		


		// animation:
		var frameRate = 20; // target rate to update screen - time slice
		var frameCount = 0;
		var animationRunning = false; 
		var gameCounter = 0;

		// plug pixel position - measured from top of screen
		var pxPositionDatum = 257; // px - datum position - when position = 0
		var pxPosition = pxPositionDatum; // px - current position

		// kinematic variables:
		var positionZero = 0;       // px - above datum at beginning of time slice
		var position = 0;			// px - above datum at end of time slice
		var velocityZero = 0;
		var positionMax = 0;		// px - maximum height
		var velocity = 0;			// px/s
		var acceleration = 0;		// px/s^2 - remains constant
		var floorPosition = 0;		// initial position of the 'floor'
		var floorElasticity = 0;	// floorElasticity of bounce - 1 = no speed loss
		var boostSpeed = 0;			// px/s  boost adds this speed
		var time = 0;				// elapsed time in seconds of the animation */
		var timeDelta = 0;			// elapsed time in seconds from the last position calc */

		// dates, timers, flags
		var curDate = new Date();
		var prevDate = curDate;
		var navTimer = 0; // seconds - used to run nav reveal sequence
		var jumpUpTimer = 0; // seconds - used to control floor level adjustment timing
		var shutdownTimer = 0; // seconds - used to run shutdown sequence
		var flag = new Array();

		// IE kludge to prevent screen flicker:
		var IEKludgeNeeded = 0;
		IEKludgeNeeded = IEWinVersion();
		if (IEKludgeNeeded > 6) { IEKludgeNeeded = 0 } ; // exempt version 7 and up


	function init() {
		// once the page elements are read the cast can be arranged
			
		// persona dramatis - get a handle for each member of the cast:
		if (document.layers){
			spritePlugA = document.layers.plugA ;
			spritePlugB = document.layers.plugB ;
			spriteSparks = document.layers.sparks ;
			spriteExplosion = document.layers.explosion ;
			spriteBigEyes = document.layers.bigEyes ;
			buttonBoost = document.layers.boost ;
			staticNav = document.layers.gNav ;
			staticLogo = document.layers.logo ;
			staticFooter = document.layers.footer ;
		}
		else if (document.all) {
			spritePlugA = document.all.plugA.style ;
			spritePlugB = document.all.plugB.style ;
			spriteSparks = document.all.sparks.style ;
			spriteExplosion = document.all.explosion.style ;
			spriteBigEyes = document.all.bigEyes.style ;
			buttonBoost = document.all.boost.style ;
			staticNav = document.all.gNav.style ;
			staticLogo = document.all.logo.style ;
			staticFooter = document.all.footer.style ;
		}
		else if (document.getElementById) {
			spritePlugA = document.getElementById('plugA').style ;
			spritePlugB = document.getElementById('plugB').style ;
			spriteSparks = document.getElementById('sparks').style ;
			spriteExplosion = document.getElementById('explosion').style ;
			spriteBigEyes = document.getElementById('bigEyes').style ;
			buttonBoost = document.getElementById('boost').style ;
			staticNav = document.getElementById('gNav').style ;
			staticLogo = document.getElementById('logo').style ;
			staticFooter = document.getElementById('footer').style ;
		}

		// initial screen appearance:
		staticNav.visibility = 'hidden' ;
		staticLogo.visibility = 'hidden' ;
		staticFooter.visibility = 'hidden' ;
		
		spritePlugA.visibility = 'hidden' ;
		spritePlugB.visibility = 'hidden' ;
		spriteSparks.visibility = 'hidden' ;
		spriteExplosion.visibility = 'hidden' ;
		spriteBigEyes.visibility = 'hidden' ;
		
		spritePlugA.top = '-900px' ; // off the screen, to the top
		spritePlugB.top = '-900px' ;
	}


	function runAnimation() {
		gameCounter++ ;
		
		if (gameCounter == 1 ) {
			// first time through (on load)
			setTimeout("animation()",300); // ms delay before animation begins
		} else {
			// re-animate!		

			// re-initialize
			time = 0;				// elapsed time in seconds of the animation */
			timeDelta = 0;			// elapsed time in seconds from the last position calc */
			curDate = new Date();
			prevDate = curDate;
			navTimer = 0; // seconds - used to run nav reveal sequence
			jumpUpTimer = 0; // seconds - used to control floor level adjustment timing
			shutdownTimer = 0; // seconds - used to run shutdown sequence
			flag = new Array();


			animation();
		}
	}

	function boost() {

		if ( animationRunning ) {
			// boost the speed
			if (velocityZero >= 0 ) {
				velocityZero = velocityZero + boostSpeed;
			} else {
				velocityZero = velocityZero - boostSpeed;
			} 
		} else {
			// let's play some more...
			runAnimation() ;
		}
	}


	function animation() {

		animationRunning = true;

		/*** Time Calcs ***/

		// get time and timeDelta
		prevDate = curDate;
		curDate = new Date();
		timeDelta = (curDate - prevDate)/1000;
		
		// if timeDelta is too large, then set it to something realistic.
		// this occurs if the animation is interrupted (to resize screen, for example)
		if (timeDelta > 3/frameRate) timeDelta = 1/frameRate;
		time = time + timeDelta;

		var curSpeed = Math.abs(velocityZero);

		// nav timer
		if (( positionZero < 100 && curSpeed < 120 )  ||  flag['logo visible'] ) {
			// increment
			navTimer = navTimer + timeDelta ;
		} else {
			// reset 
			navTimer = 0 ;
		}	

		// jump up timer
		if (( flag['nav visible']  && curSpeed < 100 )  ||  flag['jump up'] ) {
			// increment
			jumpUpTimer = jumpUpTimer + timeDelta ;
		} else {
			// reset 
			jumpUpTimer = 0 ;
		}	

		// shutdown timer
		if (( flag['floor moved'] && curSpeed < 100 )  || flag['sparks off'] ) {
			// increment
			shutdownTimer = shutdownTimer + timeDelta ;
		} else {
			// reset 
			shutdownTimer = 0 ;
		}	


		/*** Events ***/

		if ( !flag['go'] ) {
		
			// make visible:
			spriteSparks.visibility = 'visible' ;
			buttonBoost.visibility = 'visible' ;
			spritePlugA.visibility = 'visible' ;
			if (IEKludgeNeeded) spritePlugB.visibility = 'visible' ;
			
			flag['go'] = true;
		}	

		if ( !flag['initialized'] && gameCounter == 1 ) {
			
			// initial kinematics: 
			positionZero = 450;
			positionMax = 0;
			velocityZero = -620;
			acceleration = -900;
			floorPosition = -55; // plug fits into head
			floorElasticity = 0.55;
			boostSpeed = 400;
			
			flag['initialized'] = true;
		}	

		if ( !flag['initialized'] && gameCounter > 1 ) {
			
			// 'play again' kinematics: 
			velocityZero = 400;
			positionMax = 0;
			floorPosition = -55; // plug fits into head
			
			flag['initialized'] = true;
		}	

		if ( !flag['logo visible'] && navTimer > 0.25 ) {
			staticLogo.visibility = 'visible' ;
			flag['logo visible'] = true;
		}	

		if ( !flag['nav visible'] && navTimer > 0.75 ) {
			staticNav.visibility = 'visible' ;
			flag['nav visible'] = true;
		}	

		if ( !flag['jump up'] && jumpUpTimer > 0.5 ) {
			prevVelocity = 300;
			flag['jump up'] = true;
		}	

		if ( !flag['floor moved'] && jumpUpTimer > 0.6 ) {
			floorPosition = 0;
			spriteExplosion.visibility = 'visible' ;
			flag['floor moved'] = true;
		}	

		if ( !flag['big eyes'] && gameCounter > 1 && positionMax > 450 && jumpUpTimer > 0.8 ) {
			spriteBigEyes.visibility = 'visible' ;
			flag['big eyes'] = true;
		}	


		if ( !flag['explosion done'] && jumpUpTimer > 0.8 ) {
			spriteExplosion.visibility = 'hidden' ;
			flag['explosion done'] = true;
		}	

		if ( !flag['big eyes done'] && flag['big eyes'] && jumpUpTimer > 1.3 ) {
			spriteBigEyes.visibility = 'hidden' ;
			flag['big eyes done'] = true;
		}






		if ( !flag['sparks off'] && shutdownTimer > 2 ) {
			spriteSparks.visibility = 'hidden' ;
			// buttonBoost.visibility = 'hidden' ;
			flag['sparks off'] = true;
		}	

		if ( !flag['done'] && shutdownTimer > 2.5 ) {
			spritePlugA.visibility = 'visible' ;
			spritePlugB.visibility = 'hidden' ;
			staticFooter.visibility = 'visible' ;
			flag['done'] = true;
			animationRunning = false;
			return; // All done!
		}	


		/*** Position ***/

		// calculate new postion:
		freeflight();

		// emergency exit
		if (position < -1000 || position > 5000) return;

		// move the plug to the new position
		movePlug();
		

		/*** Continue ***/

		// one more time!
		positionZero = position;
		positionMax = Math.max( position , positionMax );
		velocityZero = velocity;
		frameCount++;
		setTimeout("animation()",1000/frameRate);
	}
	


	function freeflight() {

		// calculate the position and velocity
		position =  positionZero + ( velocityZero * timeDelta) + ( 0.5 * acceleration * timeDelta * timeDelta );
		velocity = velocityZero + ( acceleration * timeDelta ) ;
		
		// does that take us through the bounce floor?
		if ( position <= floorPosition && velocity < 0 ) {
			// yes
			// at moment of impact
			position = floorPosition;


			var positionDelta = floorPosition-positionZero;
			
			// there are two real solutions to this equation : only the negative square root is calculated
			var timeDeltaBounce =  2*positionDelta / ( velocityZero - Math.sqrt( Math.abs( velocityZero*velocityZero + 2*acceleration*positionDelta ) ) );
			velocity = velocityZero + ( acceleration * timeDeltaBounce ) ;
		
			// post-bounce
			var velocityRebound = -1 * velocity * floorElasticity;
			timeDelta = timeDelta - timeDeltaBounce;

			position =  positionZero + ( velocityRebound * timeDelta) + ( 0.5 * acceleration * timeDelta * timeDelta );
			velocity = velocityRebound + ( acceleration * timeDelta ) ;


			
		}

		// check the floor
		position = Math.max( position, floorPosition );



	}




	function movePlug() {
		// move the plug on the screen
		pxPosition = Math.round( pxPositionDatum - position );
		if (IEKludgeNeeded) {
			// kludge case - alternate moves to avoid flicker
			if (frameCount%2) {		
				spritePlugA.top = pxPosition + 'px' ;
			} else {	
				spritePlugB.top = pxPosition + 'px' ;
			}	
		} else {
			// ordinary case
			spritePlugA.top = pxPosition + 'px' ;
		}
	}	

	function IEWinVersion() {
		var ua = navigator.userAgent;
		var MSIEOffset = ua.indexOf("MSIE ");
		var isWin = ua.indexOf("Win");
		if (MSIEOffset == -1 || isWin == -1) {
			return 0;
		} else {
			return parseFloat(ua.substring(MSIEOffset + 5, ua.indexOf(";", MSIEOffset)));
		}	
	}