Hmm why doesnt this work?

Tom2012 · October 2012

Trying to make a class that spawns a caveman with animation and physics.

All works fine, except the physics body is not attaching to the sprite.

Any ideas please?

Caveman = Core.class(Sprite);
 
-- Do on load
 
function Caveman:init(scene,atlas)
 
local animLoader = CTNTAnimatorLoader.new()
animLoader:loadAnimations("Animations/atlas-2-animation.tan", atlas, true)
local caveman = CTNTAnimator.new(animLoader)
caveman:setAnimation("CAVEMAN_FALLING")
 
 
caveman:addToParent(caveman)
 
caveman:playAnimation()
 
local body = scene.world:createBody{type = b2.DYNAMIC_BODY}
body:setPosition(caveman:getX(), caveman:getY());
body:setAngle(caveman:getRotation() * math.pi/180);
local poly = b2.PolygonShape.new()
poly:setAsBox((caveman:getWidth()/2)-10,10,0,4,0)
local fixture = body:createFixture{shape = poly, density = 1.0, friction = 0.1, restitution = 0.2}
local filterData = {categoryBits = 2, maskBits = 1};
fixture:setFilterData(filterData);
 
caveman.body = body
 
self:addChild(caveman)
 
 
 
--caveman.body.type = "caveman";
 
 
self:addEventListener(Event.ENTER_FRAME, self.onEnterFrame, self)
 
end

bowerandy · October 2012

@Tom2012, you don't show what you've got in your onEnterFrame() method.

By default, Gideros doesn't keep any real links between physics bodies and their associated sprites. You have to do this yourself.

Take a look at how the Sleeping Bodies example does it. You'll see that there is a global ENTER_FRAME handler that steps the physics world on by 1/60 sec. This will move the physics bodies to their new locations. However, at this point the sprites are still where they were before. What the example does is to keep another table called "actors" that has a mapping back from physics body to sprite. The ENTER_FRAME handler goes through all the bodies in the actors table and updates the position of the equivalent sprite to match.

That is one way to do it. An alternative might be to use @ar2rsawseen's new GiderosInit library. See this thread. I haven't really used this part of it but the example program seems to show an easier way to use physics where the bodies and sprites are automatically tied together.

best regards

Tom2012 · October 2012

Hello,

Thanks for the reply ;-)

I've actually got the method that updates all the box 2D bodies each frame. The physics body falls away by itself while the sprite remains at the top of the screen.

If I take the code from the class and place it on the scene, it works fine. I've got something wrong with the child / parent I think?

hgvyas123 · October 2012

are u calling Caveman:new() from scene1 and there is a enterframe event to change the position of physics body over there in that case it can happen as you have not given physics body to right instance ?

if my guess is true then try this in scene.lua

local caveman = Caveman:new()
local body = scene.world:createBody{type = b2.DYNAMIC_BODY}
body:setPosition(caveman:getX(), caveman:getY());
body:setAngle(caveman:getRotation() * math.pi/180);
local poly = b2.PolygonShape.new()
poly:setAsBox((caveman:getWidth()/2)-10,10,0,4,0)
local fixture = body:createFixture{shape = poly, density = 1.0, friction = 0.1, restitution = 0.2}
local filterData = {categoryBits = 2, maskBits = 1};
fixture:setFilterData(filterData);
 
caveman.body = body
 
 
ps i have just copy and pasted the code and havent tried that 
 
<img class="emoji" src="http://forum.gideros.rocks/resources/emoji/smile.png" title=":)" alt=":)" height="20" />

Tom2012 · October 2012

dupe

Tom2012 · October 2012

Think Ive figured it out...

If anyone in the future wants to use TNT animator and physics, in a class that spawns sprites, here's my code.

The scene:

level1 = Core.class(Sprite)
function level1:init()
 
-- Physics
 
-- Setup box2D world
self.world = b2.World.new(0, 10, true)
 
-- Variables
 
local secondsLeft = 45;
 
-- Bring in atlases
 
local Atlas2 = TexturePack.new("Atlases/Atlas 2.txt", "Atlases/Atlas 2.png");
 
-- Get images from atlas
 
local bg3 = Bitmap.new(Atlas2:getTextureRegion("bg3.png"));
local bg2 = Bitmap.new(Atlas2:getTextureRegion("bg2.png"));
local bg1 = Bitmap.new(Atlas2:getTextureRegion("bg1.png"));
local ground = Bitmap.new(Atlas2:getTextureRegion("ground.png"));
 
 
 
local clock = Bitmap.new(Atlas2:getTextureRegion("clock.png"));
 
-- Anchor points
 
bg3:setAnchorPoint(0.5,0);
bg2:setAnchorPoint(0.5,0);
bg1:setAnchorPoint(0.5,0);
ground:setAnchorPoint(0.5,0.5);
clock:setAnchorPoint(0.5,0.5);
 
-- Add to screen
 
self:addChild(bg3);
self:addChild(bg2);
self:addChild(bg1);
self:addChild(ground);
self:addChild(clock);
 
 
 
 
-- Allign
 
bg3:setPosition(application:getContentWidth()/2, 0);
bg2:setPosition(application:getContentWidth()/2, 164);
ground:setPosition(application:getContentWidth()/2, 432);
bg1:setPosition(application:getContentWidth()/2, 160);
clock:setPosition(220,35);
 
-- Setup ground
 
-- Create box2D body
 
local body = self.world:createBody{type = b2.STATIC_BODY}
body:setPosition(ground:getX(), ground:getY());
body:setAngle(ground:getRotation() * math.pi/180);
local poly = b2.PolygonShape.new()
poly:setAsBox(ground:getWidth()/2,30,0,20,0)
local fixture = body:createFixture{shape = poly, density = 1.0, friction = 0.1, restitution = 0.2}
ground.body = body
local filterData = {categoryBits = 1, maskBits = 2};
fixture:setFilterData(filterData);
 
-- Setup sounds
 
--------------------------------------------------
-- Setup countdown
--------------------------------------------------
 
-- Create text
 
local font = BMFont.new("Fonts/hairy-monster.fnt", "Fonts/hairy-monster.png");
local secondsText = BMTextField.new(font, tostring(secondsLeft));
self:addChild(secondsText);
secondsText:setPosition(250,16);
 
-- Timer
local countDown = Timer.new(1000);
 
local function reduceTime()
secondsLeft = secondsLeft -1;
secondsText:setText(tostring(secondsLeft));
end
a
countDown:addEventListener(Event.TIMER, reduceTime);
countDown:start();
 
 
 
 
--------------------------------------------------
-- Spawn Caveman Section
--------------------------------------------------
 
local function spawnCaveman()
 
local caveman = Caveman.new(self,Atlas2);
self:addChild(caveman);
 
local debugDraw = b2.DebugDraw.new()
self.world:setDebugDraw(debugDraw)
self:addChild(debugDraw)
 
end
 
 
--temp
 
spawnCaveman();
 
-- Create a function to decice whether to spawn or not
 
local timeBetween = 0;
local minTimeBetween = 2000;
local maxTimeBetween = 5000;
 
local function spawnTimer()
timeBetween = timeBetween + 100;
print(timeBetween);
 
-- over minimum time, decide whether to spawn or not
if(timeBetween > minTimeBetween) then
if(math.random(1,8) == 3) then
timeBetween = 0;
spawnCaveman()
end
end
 
-- gone over max time, spawn and reset counter
if(timeBetween >= maxTimeBetween) then
timeBetween = 0;
spawnCaveman()
end
 
end
 
local cavemanTimer = Timer.new(100);
cavemanTimer:addEventListener(Event.TIMER, spawnTimer);
cavemanTimer:start();
 
 
-- Function to update box2D world each frame
 
local function onEnterFrame() 
 
-- edit the step values if required. These are good defaults!
self.world:step(1/60, 8, 3)
 
for i = 1, self:getNumChildren() do
local sprite = self:getChildAt(i)
if sprite.body then
local body = sprite.body
local bodyX, bodyY = body:getPosition()
sprite:setPosition(bodyX, bodyY)
sprite:setRotation(body:getAngle() * 180 / math.pi)
end
end
end
 
--run world
self:addEventListener(Event.ENTER_FRAME, onEnterFrame)
 
 
-- end of sceneManager stuff
 
end

And the class is:

Caveman = Core.class(Sprite);
 
-- Do on load
 
function Caveman:init(scene,atlas)
 
--local atlas2 = TexturePack.new("Atlases/Atlas 2.txt", "Atlases/Atlas 2.png")
 
local animLoader = CTNTAnimatorLoader.new()
animLoader:loadAnimations("Animations/atlas-2-animation.tan", atlas, true)
local caveman = CTNTAnimator.new(animLoader)
caveman:setAnimation("CAVEMAN_FALLING")
caveman:addToParent(caveman)
caveman:playAnimation()
 
self:addChild(caveman)
 
local body = scene.world:createBody{type = b2.DYNAMIC_BODY}
body:setPosition(self:getX(), self:getY());
body:setAngle(self:getRotation() * math.pi/180);
local poly = b2.PolygonShape.new()
poly:setAsBox((self:getWidth()/2)-10,10,0,4,0)
local fixture = body:createFixture{shape = poly, density = 1.0, friction = 0.1, restitution = 0.2}
local filterData = {categoryBits = 2, maskBits = 1};
fixture:setFilterData(filterData);
self.body = body
 
self.body:setPosition(math.random(0,320), 10);
 
self:addEventListener(Event.ENTER_FRAME, self.onEnterFrame, self)
 
end
 
function Caveman:onEnterFrame(event)
 
-- Do on enterFrame
 
--[[
if(self:getY() > 300) then
 
self:getParent().world:destroyBody(self.body) -- destroy physics body
 
self:removeEventListener(Event.ENTER_FRAME, self.onEnterFrame, self) -- remove event listener
 
self:getParent():removeChild(self); -- finally, remove sprite
 
end
--]]
end
 
 
-- Some other function
 
function Caveman:SpawnCaveman(atlas,scene,x,y)
 
end

Thank you!

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