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This is basically a wrapper (with some extra features like drawing debug information, etc.) for a physics engine called Box2D. It is a WIP, because there are many more features I would like to add before it is completely finished. Also, so that you can suggest features you would like to see added

If you like this physics engine, please donate some money to Erin Catto, the engine's creator

H4ck1d has kindly offered to work on the help files, and is doing so at the moment. So all credit for those when they're finished to him

Here is the current download (Box2D v1.4.1)

Here's a screeny of the example two posts down:


There are no help files yet (see above), but I will give a brief explanation of how to use it here (you can get a command list from the keywords file)

Before you can start creating things, you need to make a WORLD object. This is basically the container for the simulation. You can have more than one world. Here is code to create a world:
+ Code Snippet

myworld = b2CreateWorld(-2000,-2000,2000,2000,0,50,1)

The first four parameters define the maximum size of the world. It is better to make this too large rather than too small.
The next two parameters define the gravity X and Y of the world.
The last paramter determines whether objects go to 'sleep' when they stop moving (improves performance).

The engine is tuned to using metres and radians as the units, so you can use the command b2SetUnits to alter this. You should use this BEFORE any other commands, and it affects all worlds.
+ Code Snippet

b2SetUnits 10,-0.017453292519943295769236907684886

This will make it so that each unit is 1/10th of a metre, and so that angles are in degrees rather than radians. It also inverts the angle, because DBP has the point 0,0 at the top left whereas normally it is at the bottom left.

An easy way to draw the simulation to the screen is by using the command b2DrawDebugInfo:
+ Code Snippet

b2DrawDebugInfo myworld,0,0,1,1

The first parameter is the world to draw, the next two define the top-left corner of the world, and the last two are for scaling the output in the X and Y directions.

Shapes:
Shapes define a collision shape. They can be created with any of these commands:
b2CreateCircleShape
b2CreateBoxShape
b2CreatePolygonShape

Body templates:
Body templates contain one or more shapes. They are templates for bodies.

Bodies:
Bodies are created directly from a body template. This allows you to create many identical bodies in the simulation with fewer commands. These are part of the actual simulation rather than just data. To create a body from a body template, use b2CreateBody. To qquickly make a body without worrying about shapes or body templates, use b2CreateCircleBody or b2CreateBoxBody.

Joints:
These are not fully implemented yet, but you can do simle things with them. They can be created using b2CreateDistanceJoint, b2CreateRevoluteJoint and b2CreatePrismaticJoint.


Feedback and suggestions are welcome

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Sounds great! I will definitely try this out when I get a chance.

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Here is a small demo program to show off the engine

To run it without downloading the image, simply comment out the 4th line. The image you need otherwise, is attached.

EDIT: Updated to work with current version (also gets rid of jitter!)
+ Code Snippet

sync on : sync rate 60 : backdrop off

REM COMMENT THE NEXT LINE TO DISABLE IMAGES
#constant USE_IMAGES 1

if USE_IMAGES
    load image "Crate.png",1,1
    sprite 1,-100,-100,1
    set sprite 1,0,0
    offset sprite 1,25,25
endif

b2SetUnits 0.1,0.017453292519943295769236907684886

myworld = b2CreateWorld(-2000,-2000,2000,2000,0,500,1)

floorbody = b2CreateBoxBody(myworld,800,20,0,0,0.5)
b2PositionBody floorbody,512,700
BodyCount = 1

dim Bodies(-1) as integer

ink rgb(200,200,200),0

do
    if rnd(20) = 1
        newbox = b2CreateBoxBody(myworld,50,50,1,0.2,0.5)
        b2PositionBody newbox,rnd(500)+400,rnd(200)
        inc BodyCount
        array insert at bottom Bodies(0)
        Bodies(BodyCount-2) = newbox
    endif
    b2Step myworld
    if USE_IMAGES
        for i = 0 to BodyCount-2
            if b2GetBodyY(Bodies(i)) > 800
                b2DeleteBody myworld,Bodies(i)
                array delete element Bodies(0),i
                dec i
                dec BodyCount
            else
                rotate sprite 1,b2GetBodyAngle(Bodies(i))
                paste sprite 1,b2GetBodyX(Bodies(i)),b2GetBodyY(Bodies(i))
            endif
        next i
    else
        b2DrawDebugInfo myworld,0,0,1,1
    endif
    box 112,690,912,710
    text 0,0,str$(screen fps())
    text 0,20,"Body count: "+str$(BodyCount)
    sync
    cls 0
loop

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Awsome work Diggsey. Glad Box2D is workin' for ya now. I'm pretty sure many people will find use of this. ^_^



Cheers,

-naota

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Won't run I'm afraid. It keeps popping up an error message asking if I would like to send an error report.

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I don't know why it would do that...

Are your running a 64-bit version of windows?

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Will it have PIXEL PERFECT COLLISION??

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@aluseus GOD
There's no such thing as pixel perfect collision in physics engines. They use VECTOR COLLISION. With vector collision, the accuracy depends entirely on the number of shapes and vertices each body contains. Obviously, the more shapes and vertices there are, the longer it takes to check collision against them.

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I made a small demo alternation to diggseys... Left click for "waiting" creation of boxes... Right click for the MADNESS!


Cheers,

-naota

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I jave the same probelm as teh coder....

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That's truly awesome Diggsey. Could this work with any shape, or does it just work width squares at the moment?

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@TEH_CODERER and flashing snall
I helped diggsey solve his problem (Told you Release mode was better ) with the DLL, as I was having a similar problem... Except it would just close without any message (My computer does that, disabled the error reporting).

In addition to that, it's now only 80KB in size instead of 170~KB.

@diggsey
Hope it's okay that I post that.


Cheers,

-naota

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Looks cool Diggsey!

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Could you uses polygons?

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This looks really cool! But it doesn't work on my computer . It crashes when I try to run it. I hope you can get it to work, because I would really find it useful! Keep up the good work Diggsey!

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@H4ck1d
Have you tried running the example I made? It has an executable file with it..


Cheers,

-naota

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Oh wow I feel stupid for missing that; I couldn't understand where the fix was that you were talking about . Thanks aaron! It works! This is sweet!

[Edit]?!!!! Wha.... when I compile it myself, it doesn't work! Your compiled version runs, but when I compile it, it crashes... I don't get it!

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It's the DLL. I helped diggsey fix it. It has something to do with MSVCD DLL, and changing to MSVCR DLL fixed it.


Cheers,

-naota

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Ohh, I get it. lol. So when will an updated dll be available to use?

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Diggsey said (Before going to sleep) that he was going to upload it "tomorrow", which should be today in a few hours.


Cheers,

-naota

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Good guess

Here is the updated version, which will hopefully fix all your problems It ia also less than half the size

@Zotoaster + aluseus GOD
This will work with any convex shape with 3 to 8 vertices by simply by using the polyhon shape commands. To make concave shapes or shapes with more than 8 vertices, you have to make multiple convex shapes, and attach them all to a body template. If nobody has done it already by the time this is nearly finished, I will probably make an editor to make it easier to make collision shapes for an image

@Everybody
Thanks for the feedback, and this is still a long way from being finished, so look out for the following:

- More types of joint
- Limiters on joints
- Motors on joints
- Setting friction on individual shapes (means multiple frictions per body are possible)
- Anything else that gets added to the Box2D engine (it is still in active developement)

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yea! it works now. thanks a lot, this is reaaaaaallllly cool. just waiting for the help files now. !!!!

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When body's reached 242 it crashed. works nice though.

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I have nearly finished a version with motors and limiters, so later today it will be released. (I will make a demo with a car that you can drive up ramps and things as well)

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hey diggsey, can you add support for convex shapes? Please? I mean is it really that hard?

Oh could you add more useful things like:
Character/Enemy Creation
Character Gravity and Physics

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@aluseus GOD
As I have said, you CAN make convex shapes! If you really mean concave shapes, then these are also possible, just by using multiple convex shapes in the same body.

Here is a picture showing what I mean:

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This looks very cool. Maybe i'll give it a bash someday.

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No, I mean, if its that simple, cant you build it in?

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@aluseus GOD
It's simple to do, but very difficult to program something to do it automatically There are more important things first anyway

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Here is a screeny of a demo I made with the new commands



It drives with a motor applied to the back wheel joint. You can control the car with the arrowkeys and spacebar, and hopefully I will be able to release the new version of the plugin so that you can compile it soon

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This is good, I'm whipping up an editor and some simple level sprites, and using this plugin to make a quick and easy mario land-esque game.

One thing though- is there a way to return collision against individual collision lines? For example, if I had some spikes, could I make it so the player was hurt only if he landed atop them?


Keep it up!

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Good job diggsey.

Cheers,

-naota

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@MonoCoder
That will be the next thing on my list Can't wait for the editor

@Aaron
Thanks (and for the car)

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this is awsome. its going to add some great effects to par 2d games. bullets will be fun to play with....

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<irrelevent now>

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NEW RELEASE!!!

This release has these features:
Motors
Limits (untested)
Contact list
First two commands which use PARTS

Parts are just like shapes, but they are the shapes after they have been added to a body. This allows you get extra information about collision, and also change settings on a per-part basis for each body. This will probably be finished by next release

You can download the latest .dll and .ini file from the top post

Here is the code for the car example from above as promised:
+ Code Snippet

sync on

load image "Car.png",1,1
load image "Tire.png",2,1
sprite 1,-200,-200,1
sprite 2,-200,-200,2
offset sprite 1,68,22
offset sprite 2,12,12

b2SetUnits 0.1,0.017453292519943295769236907684886

MyWorld = b2CreateWorld(-2000,-2000,2000,2000,0,50,1)

MyFloor = b2CreateBoxBody(MyWorld, 200, 50, 0, 0.3, 5)
MyFloor2 = b2CreateBoxBody(MyWorld, 1024, 50, 0, 0.3, 5)
MyFloor3 = b2CreateBoxBody(MyWorld, 1024, 50, 0, 0.3, 5)
MyFloor4 = b2CreateBoxBody(MyWorld, 1024, 50, 0, 0.3, 5)
carbase = b2CreateBoxShape(135,10)
cartop = b2CreateBoxShape(80,25)
cartemplate = b2CreateBodyTemplate()
b2AddShapeToBodyTemplate cartemplate,carbase,2,8,0,1,0.3
b2AddShapeToBodyTemplate cartemplate,cartop,-10,-5,0,1,0.3
MyCar = b2CreateBody(MyWorld, cartemplate)
MyWheel1 = b2CreateCircleBody(MyWorld, 12, 1, 0.3, 2500)
MyWheel2 = b2CreateCircleBody(MyWorld, 12, 1, 0.3, 2500)
b2PositionBody MyFloor,512,670
b2PositionBody MyFloor2,512,700
b2PositionBody MyFloor3,974,600
b2PositionBody MyFloor4,50,600
b2RotateBody MyFloor,-20
b2RotateBody MyFloor3,-70
b2RotateBody MyFloor4,70
b2PositionBody MyCar,512,335
b2PositionBody MyWheel1,460,362
b2PositionBody MyWheel2,564,362
MyAxel1 = b2CreateRevoluteJoint(MyWorld, MyCar, MyWheel1, 460,362)
MyAxel2 = b2CreateRevoluteJoint(MyWorld, MyCar, MyWheel2, 564,362)
b2SetJointMotorSpeed MyAxel1,1000

load image "Plain.png",3,1

sprite 3,-2000,-2000,3
offset sprite 3,50,50
set sprite diffuse 3,150,150,150

do
    if upkey()
        b2SetJointMotorSpeed MyAxel1,1000
        b2SetJointMotorForce MyAxel1,200
    else
        if downkey()
            b2SetJointMotorSpeed MyAxel1,-1000
            b2SetJointMotorForce MyAxel1,50
        else
            b2SetJointMotorForce MyAxel1,0
        endif
    endif
    if spacekey()
        b2SetBodyLinearVelocity MyCar,b2GetBodyLinearVelocityX(MyCar),-100
    endif
    torque = rightkey()-leftkey()
    b2ApplyTorque MyCar,torque*50000
    b2Step MyWorld
    rotate sprite 1,b2GetBodyAngle(MyCar)
    paste sprite 1,b2GetBodyX(MyCar),b2GetBodyY(MyCar)
    rotate sprite 2,b2GetBodyAngle(MyWheel1)
    paste sprite 2,b2GetBodyX(MyWheel1),b2GetBodyY(MyWheel1)
    rotate sprite 2,b2GetBodyAngle(MyWheel2)
    paste sprite 2,b2GetBodyX(MyWheel2),b2GetBodyY(MyWheel2)
    if a
        box 100,100,110,110
    endif
    a = 1-a
    stretch sprite 3,200,50
    rotate sprite 3,-20
    paste sprite 3,512,670

    stretch sprite 3,1024,50
    rotate sprite 3,0
    paste sprite 3,512,700

    stretch sprite 3,1024,50
    rotate sprite 3,-70
    paste sprite 3,974,600

    stretch sprite 3,1024,50
    rotate sprite 3,70
    paste sprite 3,50,600

    sync
    cls 0
loop

The images needed are attached.

The controls:
Upkey/downkey - Accelerate/reverse
Rightkey/leftkey - Lean forward/backward
Spacekey - Fly straight up in the air

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parameter mismatch in expression 'b2createboxbody' at line 18.


otherwise, this is very cool!
the reason i gave up on my last 2d platformer is because i couldn't find any way to make 2d physics.

do you think you will be able to fix the way the crates vibrate, so that they actually come to a complete halt?

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I get parameter mismatches at lines 14-17 and 24-25, and commands not understood at lines 38, 48-49, 52-53 and 55.

On commenting all of these out, the program compiles then crashes immediately with a dialog box stating that it "Failed to load DLL (4: PhysicsPlugin.dll)."


edit: this is with the latest version, using the example two posts above.

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@el zilcho
That was just an error I made with the SetUnits function. Set it to 0.1 or 0.01 and you will see that objects go to 'sleep' when their velocity goes under a certain amount. Later versions will have the option to set this amount directly

Your error is because I have not updated that example to the current version. Try the example two posts up, it is much better anyway

edit:
I have updated that example now

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i got the error when i ran the car demo though.. and ive downloaded the latest files..