- Rewrote AI to determine where ball will land, and some other stuff …

…based on angles

src/client/scenes/slime_volleyball.coffee

@@ -13,6 +13,14 @@ class SlimeVolleyball extends Scene
 		@buttons = { # create a back button
 			back: new Button(@width/2-Constants.BACK_BTN_WIDTH/2, Constants.SCOREBOARD_PADDING, Constants.BACK_BTN_WIDTH, Constants.BACK_BTN_HEIGHT, loader.getAsset('return'), loader.getAsset('return'), this)
 		}
+
+		# Set the difficulty
+		try
+			@percent = document.cookie.match(/AI_DIFFICULTY=(\d\.\d*)/i)[1]
+		catch e
+			@percent = Constants.AI_DIFFICULTY
+		finally
+			Constants.AI_DIFFICULTY = @percent # make sure it is set
 
 		@sprites = []
 		@sprites.push(@bg, @world.pole, @world.p1, @world.p2, @world.ball, @p1Scoreboard, @p2Scoreboard, @buttons.back)
@@ -59,16 +67,52 @@ class SlimeVolleyball extends Scene
 		changed
 
 	moveCPU: -> # implement a basic AI
-		if @ball.x > @pole.x && @ball.y < 200 && @ball.y > 150 && @p2.velocity.y == 0
-			@p2.velocity.y = -8
-		if @ball.x > @pole.x - @p1.width && @ball.x < @p2.x
-			@p2.x -= (Constants.MOVEMENT_SPEED*.75) + (Constants.MOVEMENT_SPEED*Constants.AI_DIFFICULTY)
-		if @ball.x > @pole.x - @p1.width && @ball.x + @ball.width + (@ball.velocity.x * Constants.AI_DIFFICULTY) > @p2.x + @p2.width && @ball.x + @ball.width < @width
-			@p2.x += (Constants.MOVEMENT_SPEED*.75) + (Constants.MOVEMENT_SPEED*Constants.AI_DIFFICULTY)
-		else if @ball.x > @pole.x - @p1.width && @ball.x + @ball.width + (@ball.velocity.x * Constants.AI_DIFFICULTY) > @p2.x + @p2.width && @ball.x + @ball.width >= @width
-			@p2.x -= (Constants.MOVEMENT_SPEED*.75) + (Constants.MOVEMENT_SPEED*Constants.AI_DIFFICULTY)
-		if @ball.x + @ball.radius > @p2.x + 30 && @ball.x + @ball.radius < @p2.x + 34
-			@p2.x += (Constants.MOVEMENT_SPEED*.75) + (Constants.MOVEMENT_SPEED*Constants.AI_DIFFICULTY)
+		return if @freezeGame
+		# Predict where the ball is going to end up
+		# Clone the ball obj
+		ball = {
+			x: @ball.x
+			y: @ball.y
+			velocity: {
+				x: @ball.velocity.x
+				y: @ball.velocity.y
+			}
+			acceleration: {
+				x: @ball.acceleration.x
+				y: @ball.acceleration.y
+			}
+		}
+		floor = @height - Constants.BOTTOM
+		while ball.y < floor - @p2.height # predicting the position where will be at slime height
+			# switch vel if hits wall
+			ball.velocity.x *= -1 if ball.x > @width || ball.x < 0
+			ball.x += ball.velocity.x * Constants.FPS_RATIO
+			ball.y += ball.velocity.y * Constants.FPS_RATIO
+			ball.velocity.y += ball.acceleration.y * Constants.FPS_RATIO
+
+		p2Pos = @p2.x + @p2.width / 2 - 14
+		pastP1 = @ball.x > @p1.x + @p1.width / 2 + @ball.radius
+		pastPole = ball.x > @pole.x
+		ballPos = @ball.x + @ball.radius
+		ballLand = ball.x + @ball.radius
+
+		# Angle between current pos, and land
+		ballAngle = Math.atan2( ballLand - ballPos, @ball.height )
+
+		# Where he wants to be to hit it (based on the angle of the ball and distance from pole)
+		# More weight is on the angle than the distance
+		# the randomness makes him stupider
+		sweetSpot = p2Pos - Constants.AI_DIFFICULTY * ( 1 - ( 1 / Constants.AI_DIFFICULTY ) * Math.random() ) * .8 * ( 2 * ( ( ( p2Pos - @pole.x ) / ( @width / 2 ) ) + 8 * ( 1.57 - Math.abs ballAngle ) ) )
+
+		# jump only if angle is steep enough, or ball will land past
+		if ( Math.abs( ballPos - sweetSpot ) <= 5 || ballPos - sweetSpot > 5 ) && @ball.y < 200 && @ball.y > 100 && @p2.velocity.y == 0 && ( ( ballAngle > -.8 && ballAngle < 0.8 ) )
+			@p2.velocity.y = -8 # jump
+		# ball will pass p2
+		if ballLand > sweetSpot + 5 # have him shoot at a lower angle if it's less steep
+			@p2.x += (Constants.MOVEMENT_SPEED*.55) + (Constants.MOVEMENT_SPEED*Constants.AI_DIFFICULTY)
+		# Ball past 1 and will land past net OR ball heading toward p1 from our side
+		else if ( ( pastP1 && pastPole ) || ( @ball.velocity.x < 0 && @ball.x > @pole.x ) ) && ballLand < sweetSpot - 5
+			@p2.x -= (Constants.MOVEMENT_SPEED*.55) + (Constants.MOVEMENT_SPEED*Constants.AI_DIFFICULTY)
 
 	draw: ->
 		# draw everything!
@@ -118,6 +162,7 @@ class SlimeVolleyball extends Scene
 			setTimeout(( => # start game in 1 second		
 				@world.reset(winner)
 				@displayMsg = null
+				@stepLen = Constants.TICK_DURATION
 				@freezeGame = false
 			), 1000)
 
@@ -126,8 +171,10 @@ class SlimeVolleyball extends Scene
 	step: (timestamp) ->
 		this.next() # constantly demand ~60fps
 		return this.draw() if @freezeGame # don't change anything!
+
 		# apply input and then step
-		@world.step() # step physics
+		@world.step( @stepLen ) # step physics
+		@stepLen = null
 		# end game when ball hits ground
 		if @world.ball.y + @world.ball.height >= @world.height-Constants.BOTTOM
 			winner = if @world.ball.x+@world.ball.radius > @width/2 then @world.p1 else @world.p2

src/shared/constants.coffee

@@ -26,7 +26,7 @@ Constants =
 	MOVEMENT_SPEED: 4
 	JUMP_SPEED: 12
 	SLIME_START_HEIGHT: 91
-	AI_DIFFICULTY: 0.25
+	AI_DIFFICULTY: 0.35
 	MSG_FONT: 'Courier, monospace, sans-serif'
 	FPS_RATIO: 24 / 16 # in relation to what the initial speeds were set for (16ms)
 	TICK_DURATION: 24 #ms

src/shared/world.coffee

@@ -76,13 +76,14 @@ class World
 		@lastStep = now unless dontIncrementClock
 
 		# automatically break up longer steps into a series of shorter steps
-		if interval >= 1.3 * tick
+		if interval >= 1.3 * tick && @deterministic
 			while interval > 0
 				newInterval = if interval >= 1.3 * tick then tick else interval
 				this.step(newInterval, dontIncrementClock)
 				interval -= newInterval
 			return # don't continue stepping
-		else interval = tick
+		else if @deterministic
+			interval = tick
 
 		@numFrames = interval / tick