Tutorial 14 - An Extended Ship Class

Colors.lua

--# Colors
-- Make available the predefined colors from UIColor
--
-- Version 1.1

blackColor = color(0, 0, 0)
darkGrayColor = color(85, 85, 85)
lightGrayColor = color(170, 170, 170)
whiteColor = color(255, 255, 255)
grayColor = color(128, 128, 128)
redColor = color(255, 0, 0)
greenColor = color(0, 255, 0)
blueColor = color(0, 0, 255)
cyanColor = color(0, 255, 255)
yellowColor = color(255, 255, 0)
magentaColor = color(255, 0, 255)
orangeColor = color(255, 128, 0)
purpleColor = color(128, 0, 128)
brownColor = color(153, 102, 51)
clearColor = color(0, 0, 0, 0)
lightTextColor = color(255, 255, 255, 153)
darkTextColor = color(0, 0, 0)

-- Reefwing specific Colours

lightRedColor = color(243, 157, 33)
lightBlueColor = color(0, 0, 255, 128)

Main.lua

--# Main
-- SpaceWar!

-- Define display mode and supported iPad orientations.
-- This way we don't forget to handle orientation changes if required.
-- "ANY" is the default assignment.

--displayMode(FULLSCREEN)
supportedOrientations(ANY)

function setup()

   version = 1.0

   saveProjectInfo("Description", "Codea SpaceWar v"..version)
   saveProjectInfo("Author", "Reefwing Software")
   saveProjectInfo("Date", "18th August 2012")
   saveProjectInfo("Version", version)
   saveProjectInfo("Comments", "Original Release.")

   myShip = Ship(100, HEIGHT - 100)
   enemyShip = Ship(WIDTH - 100, 100, true, 180)
   starField = Twinkle(50)
end

-- This function gets called once every frame
function draw()

   -- This sets a black background color & draws the star field

   background(blackColor)
   starField:draw()

   -- Do your drawing here

   myShip:draw()
   enemyShip:draw()

   if intersectRects(myShip.x, myShip.y, myShip.width, myShip.height,
                     enemyShip.x, enemyShip.y, enemyShip.width, enemyShip.height) then
       print("BANG!!!")
   end

end

function touched(touch)
   myShip:touched(touch)
   enemyShip:touched(touch)
end

Math.lua

--# Math
function pointInRect(pointX, pointY, x, y, w, h)

   -- Returns true if point (pointX, pointY) is within the rectangle
   -- with lower left corner at (x, y) with a width of w and a
   -- height of h.
   --
   -- Reefwing Software (www.reefwing.com.au)
   -- Version 1.0

   if pointX >= x and pointX <= x + w and pointY >= y and pointY <= y + h then
       return true
   else
       return false
   end

end

function intersectRects(x1, y1, w1, h1, x2, y2, w2, h2)

   if x1 + w1 >= x2 and x1 <= x2 + w2 and y1 + h1 >= y2 and y1 <= y2 + h2 then
       return true
   else
       return false
   end

end 

function pointOffScreen(pointX, pointY)

   -- Returns true if the point(pointX, pointY) is off screen.

   if pointX < 0 or pointX > WIDTH or pointY < 0 or pointY > HEIGHT then
       return true
   else
       return false
   end

end

function math.hypot2(x, y)

   -- This function also returns the hypotenuse of a right angle triangle
   -- from (0, 0) to (x, y).
   --
   -- math.hypot2() is mathematically equivalent to math.hypot() but
   -- reduces the chance of an over or underflow, since y/x can't overflow
   -- and the square root is computed over a value between 1 and 2.
   --
   -- Reefwing Software (www.reefwing.com.au)
   -- Version 1.0

   x = math.abs(x)
   y = math.abs(y)
   t = math.min(x, y)
   x = math.max(x, y)
   y = t

   return x * math.sqrt(1 + (y/x)*(y/x))

end

function math.polar(x, y, originX, originY)

   -- Usage: math.polar(x, y) - origin is assumed at (0, 0)
   --        math.polar(x, y, originX, originY)
   --
   -- This function converts from cartesian co-ordinates (x, y) to
   -- polar co-ordinates (distance, angle) using the two functions:
   --
   --    1. distance = hypot(x, y) - the hypotenuse of a right-angle triangle; and
   --    2. angle = atan2(x, y) - is the arc tangent of y/x in radians.
   -- 
   -- Since nil evaluates to false in Lua, you can use "or" to assign a default value.
   --
   -- Reefwing Software (www.reefwing.com.au)
   -- Version 1.0

   local oX = originX or 0
   local oY = originY or 0
   local dx = x - oX
   local dy = y - oY

   local distance = math.hypot2(dx, dy)
   local angleInDegrees = math.deg(math.atan2(dy, dx))

   -- Functions may return multiple results in Lua.

   return distance, angleInDegrees

end

Ship.lua

--# Ship
Ship = class()

function Ship:init(x, y, enemy, heading)
   -- you can accept and set parameters here
   self.x = x or 0
   self.y = y or 0
   self.enemy = enemy or false
   self.speed = 3
   self.heading = heading or 0
   self.mode = CORNER            -- Supported co-ordinate modes are CENTER or CORNER
   self.width = 50
   self.height = 35
   self.selected = false
   self.imageMesh = mesh()
   self.destination = nil
   self.shipMoving = false

   -- Ship Image Mesh Vertices

   self.imageMesh.vertices = {vec2(0, 0), vec2(0, self.height), vec2(self.width, self.height/2), 
                              vec2(0, 0), vec2(self.height/2, self.height/2), 
                              vec2(0, self.height)}

   -- Set the colour of every vertex in the mesh
   -- red for enemy ships, blue for friendly.

   if enemy then
       shipColorTable = {whiteColor, whiteColor, redColor, 
                         blackColor, blackColor, blackColor,}
   else
       shipColorTable = {blueColor, blueColor, lightBlueColor, 
                         blackColor, blackColor, blackColor,}
   end
   self.imageMesh.colors = shipColorTable

end

-- If a destination is set, the ship will automatically move
-- towards this point each frame.

function Ship:updatePosition()

   local distance, heading = math.polar(self.destination.x, self.destination.y, self.x, self.y)

   if distance <= self.width or pointOffScreen(self.x, self.y) then
           self.shipMoving = false -- approximate destination reached
   else
       self.heading = heading
       if self.destination.x > self.x then
           self.x = self.x + self.speed
       elseif self.destination.x < self.x then
           self.x = self.x - self.speed
       end
       if self.destination.y > self.y then
           self.y = self.y + self.speed
       elseif self.destination.y < self.y then
           self.y = self.y - self.speed
       end
   end

end

function Ship:draw()

   -- Codea does not automatically call this method
   -- Draw the ship at the current (x,y) co-ordinates,
   -- once updated if it is moving.

   pushStyle()
   pushMatrix()

   if self.shipMoving then
       self:updatePosition()
   end

   if self.mode == CORNER then
       translate(self.x, self.y)
   elseif self.mode == CENTER then
       translate(self.x + self.width/2, self.y + self.height/2)
   else
       print("ERROR:: Ship translation failed - unsupported co-ordinate mode.")
   end
   rotate(self.heading)

   -- draw rectangle indicating selected ship

   if self.selected then
       stroke(greenColor)
       strokeWidth(3)
       fill(clearColor)
       rect(-10, -10, self.width + 20, self.height +20)
   end

   -- draw ship

   self.imageMesh:draw()

   popMatrix()
   popStyle()

end

function Ship:touched(touch)
   -- Codea does not automatically call this method
   -- pointInRect() function is located in Collisions

   if not self.enemy and touch.state == ENDED then 
       -- if touch is on the rectangle bounding the ship
       if pointInRect(touch.x, touch.y, self.x, self.y, self.width, self.height) then
           if self.selected then
               self.selected = false
           else
               self.selected = true
           end
       elseif self.selected then -- if selected set ship destination
           local dx, dy
           if self.mode == CORNER then
               dx, dy = touch.x - self.width/2, touch.y - self.height/2
           else
               dx, dy = touch.x, touch.y
           end
           if self.destination == nil then
               self.destination = vec2(dx, dy)
           else
               self.destination.x, self.destination.y = dx, dy
           end
           self.shipMoving = true
           print("Ship destination - x: "..self.destination.x.." y: "..self.destination.y)
       end
   end

end

Twinkle.lua

--# Twinkle
Twinkle = class()

-- Twinkle Class courtesy of Ipad41001
-- December 2011
--
-- Creates a nice twinkling star background.
--
-- Modified: numberOfStars variable added
-- 
-- Version 1.1

function Twinkle:init(numberOfStars)
   -- you can accept and set parameters here
   st = {}
   ns = numberOfStars -- number of stars
   for i = 1,ns do
       if math.random(2) == 1 then g = .25 else g = -.25 end
       l = 5 + (math.random(39)/4)
       st[i] = {g=g,l=l,x=math.random(WIDTH),y=math.random(HEIGHT)}
   end
end

function Twinkle:draw()
   -- Codea does not automatically call this method
   pushStyle()
   rect(0,0,1,1)
   -- background(20, 46, 181, 255)
   background(0, 0, 0)
   strokeWidth(3)
   lineCapMode(SQUARE)
   stroke(255, 255, 255, 255)
   fill(255, 255, 255, 255)
   for i = 1,ns do
       if st[i].l <= 5 and math.random(2) == 1 then st[i].g = .25
       elseif st[i].l >= 15 and math.random(2) == 1 then st[i].g = -.25 end
       st[i].l = st[i].l + st[i].g 
       ll = (15 - st[i].l)/2
       line(st[i].x-st[i].l,st[i].y,st[i].x+st[i].l,st[i].y)
       line(st[i].x,st[i].y-st[i].l,st[i].x,st[i].y+st[i].l)
       line(st[i].x-ll,st[i].y-ll,st[i].x+ll,st[i].y+ll)
       line(st[i].x+ll,st[i].y-ll,st[i].x-ll,st[i].y+ll)
       ellipse(st[i].x,st[i].y,6,6)
   end
   popStyle()
end