Polygon shape - runtime error

[Sky Rider]

Hey everyone!
I've been working on something like spaceship TDS. So, to test Box2D engine, I first used circle shapes for my spaceships, but then I thought it would be kinda cool to use polygons to make it look more realistic. I made a shape with 8 vertices, and love crashed with a runtime error! Then I discovered that even such a simple polygon as

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love.physics.newPolygonShape(0, 0, 0, 64, 64, 64, 64, 0) --square polygon, anti-clockwise

doesn't work. Microsoft Visual C++ cryes that "This application has requested the Runtime to terminate it in an unusual way". I tryed to install the last MVC++ 2010, then I updated my video drivers (my video card is ATI Mobility Radeon HD 3470 and OS is Windows Vista, by the way). Nothing helped
Could anyone help me? Thanks in advance!

[OmarShehata]

Does the creation of other bodies work normally? Only thing I can think of to get that one line not to work is that you might be calling it before setting up your world.

[Sky Rider]

I havent tested all the bodies, but circle and rectangle works pretty good. Thats strange since a rectangle, according to wiki, is just a type of polygon.
And the problem is certainly not in the code: when I replace a polygon with a circle or a rectangle, it does work. I think it's something with my computer, maybe some drivers missing... I'll try to update my staff.

[Sky Rider]

Somehow, polygon shapes do work when I create another project... Fine, I'll try to experiment with my code.

[Sky Rider]

I've solved the problem by moving the chunk of code that determines mass, inertia and position of the body. Now my code looks like this:

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self.body = love.physics.newBody(world, x, y, "dynamic")
self.body:setMass(25)
self.body:setInertia(25)
self.body:setPosition(x, y)
self.shape = love.physics.newPolygonShape(0, 0, 71, 0, 95, 11, 102, 22, 102, 60, 95, 71, 71, 82, 0, 82)
self.fixture = love.physics.newFixture(self.body, self.shape)
self.fixture:setRestitution(0.05)

However, now I have another problem: changing mass doesn't seem to work. There's no difference between a mass of 25 and 2500... The force rotates and moves it with the same effect. Why could that happen?

[OmarShehata]

I've solved the problem by moving the chunk of code that determines mass, inertia and position of the body. Now my code looks like this:

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self.body = love.physics.newBody(world, x, y, "dynamic")
self.body:setMass(25)
self.body:setInertia(25)
self.body:setPosition(x, y)
self.shape = love.physics.newPolygonShape(0, 0, 71, 0, 95, 11, 102, 22, 102, 60, 95, 71, 71, 71, 0, 71)
self.fixture = love.physics.newFixture(self.body, self.shape)
self.fixture:setRestitution(0.05)

However, now I have another problem: changing mass doesn't seem to work. There's no difference between a mass of 25 and 2500... The force rotates and moves it with the same effect. Why could that happen?

More info please. Where is the code where you apply the force? Where exactly do you apply a force?

[Sky Rider]

I apply the force using controls:

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function math.lengthdir(len, dir)
	return len * math.cos(dir), len * math.sin(dir)
end

function hostPlayer:checkControls(dt)
	if love.keyboard.isDown('w') then
		self.body:applyForce(math.lengthdir(1000, self.body:getAngle()))
	elseif love.keyboard.isDown('s') then
		self.body:applyForce(math.lengthdir(1000, self.body:getAngle() + math.pi))
	end
	if love.keyboard.isDown('d') then
		self.body:applyAngularImpulse(100)
	elseif love.keyboard.isDown('a') then
			self.body:applyAngularImpulse(-100)
	end
end

It happens every timestep.
Here's all code that uses physics:

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function love.load()
	world = love.physics.newWorld(0, 0, true)
	love.physics.setMeter(64)
	hostPlayer:create(0, 0, "EaJet", 0, 0, 0, 0.5) -- this function calls physical:init (a parent class) with the same arguments.
end

function physical:init(x, y, image, speed, dir, angle, imageScale)
	table.insert(objList, self)
	self.id = table.maxn(objList)
	self.image = love.graphics.newImage(image .. ".png")
	self.imageWidth = self.image:getWidth()
	self.imageHeight = self.image:getHeight()
	if imageScale == nil then
		self.imageScale = 1
	else
		self.imageScale = imageScale
	end
	
	self.body = love.physics.newBody(world, x, y, "dynamic")
	self.body:setMass(25)
	self.body:setInertia(25)
	self.body:setPosition(x, y)
	self.shape = love.physics.newPolygonShape(0, 0, 71, 0, 95, 11, 102, 22, 102, 60, 95, 71, 71, 82, 0, 82)
	self.fixture = love.physics.newFixture(self.body, self.shape)
	self.fixture:setRestitution(0.05)
	
	if angle == nil then
		self.body:setAngle(0)
	else
		self.body:setAngle(math.rad(angle))
	end
	
	if speed ~= nil then
		self.body:setLinearVelocity(math.lengthdir(speed, dir))
	end
end

--Then hostPlayer:checkControls(dt) is called every frame.

Basically, there's nothing else that uses physics.

[Boolsheet]

Box2D recalculates the mass for the body if you attach a new fixture. If you want to change the mass, do it after the attaching.

Also, I recommend using Body:setMassData because Body:setMass doesn't catch exceptions in 0.8.0 (which is probably why it terminated for you).

[Sky Rider]

Thanks!
But for some reason an error occures:
"Box2D error: m_l > 0.0f"
And it doesn't matter whether I put "setMassData" before fixture or after it.

[Boolsheet]

That means the rotational inertia is too low.

I would explain, but I don't understand that part of physics and Box2D.