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tato123
Member
I'm trying to figure out a way to simulate water as seen on games like locoroco where the water seems bouncy and elastic rater than acting like a true fluid. I'd preferably like to figure out how to achieve the effect using chipmunk but I can work with box2d if necessary. Any suggestions would be great! Thanks everyone.
@22 seconds they briefly show that elastic bouncy type water
| Get the Flash Videos |
That game is beautiful. I have no idea how they made that game so squishy but it sure looks difficult.
Maybe you could simulate something similar using chipmunk springs/pin joints connected to lots of circles? It's a hack but it might work.
For example, say a 0 is a small water node, 1px in size, and a - is a very short but flexible spring. Pipes (|) are objects with static mass to keep the water in one place.
|--0-0-0-0-0-0-0-0-0-0-0--|
You'd have to cancel out gravity for each node, but it may work with some funky collision logic and enough water molecule nodes.
For drawing, you could just make each 0 a vertex and draw it using OpenGL's glDrawArrays.
No idea if this would perform at all, though!
If anyone has a good suggestion here, I'd love to hear it.
Duckwit
Member
The PSP has a higher performance rate, better processing capabilities compared to the iPhone. It looks like with that game they have used a soft-body physics engine.... But that is achievable with the right knowledge.... but I don't think with cocos2d. Disney Interactive made the game Jelly Car (and Jelly Car 2) which is soft-body.
max9xs
Member
| Get the Flash Videos |
See this demo ....!
Achieve this using chipmunk and Box2d is very very difficult..
It may be possible for cocos2d to apply this framework without loosing performance.. may be or may be not.. !
Cheers..
A few months ago I did something similar in cocos2d-python + pymunk.
The performance wasn't so great on my notebook, so I wouldn't expect a good performance on the iPhone either.
I used pymunk (chipmunk wrapper for python) but it can be done in box2d too.
Basically:
- You have to create N bodies. The higher the number, the better the circle effect. Position them using the circle formula
- Create another body in the center of the circle
- Connect all the bodies with slide joints.
- Paint the object using a GL_TRIANGLE_FAN <-- Very important.
Code in python:
http://bazaar.launchpad.net/~ricardoquesada/worldst/minigame-branch/files
Screenshot from the game:
max9xs
Member
Yes Exactly ,see this video... http://thayer-remodeling.com/stuff/jelloPhysics.mov
max9xs
Member
Thanks riq, Got some idea, i would like to make some classes to achieve this, like circle, eclipse, polygon and line all that based on chipmunk, to achieve like that,,
I think slide Joint would be much better..
But i am confused, how to attach image with whole combine shape ? any idea ?
@mac9xs:
Take a look at the class Gomita:
http://bazaar.launchpad.net/~ricardoquesada/worldst/minigame-branch/annotate/head:/mini_games/jelly/__init__.py#L114
in particular to the draw method:
http://bazaar.launchpad.net/~ricardoquesada/worldst/minigame-branch/annotate/head:/mini_games/jelly/__init__.py#L158
You could do the same with cocos2d-iphone
Updated: You said image ? a texture ?.... mmm.... yes, you should do something similar to the draw method... you should create "radial" texture coordinates, and then map them with the new vertices... I think that should work.
@tato123:
I think that Box2d also has slide joints, but with another name.... I think they are called prismatic joints, but I might be confusing them with another ones.
Slide Joint definition:
http://code.google.com/p/chipmunk-physics/wiki/cpConstraint
tato123
Member
@riq :
I've finally got a working sample of this, I'll post the code tonight. It took some work trying to figure out the perfect spacings for the slide joints and circle bodies to pull off this effect. I'm still not sure how to go about actually drawing on top of the physics objects, at the moment I'm using box2d debug drawing to see that I'm getting the physics effect I want.
To get a tweakable wave I've created a kinematic body for the endpoints and as I step through the physics simulation I adjust the bodies up and down, ends up looking like a wave generated by a whip and behaves in an elastic manner on collisions.
max9xs
Member
I have developed the same code in chipmunk..(as your description says)
Its works awesome ! Very very interesting...no frame-rates down.. but the problem is that If i use it as a main characters of the game
Its surface points sometimes crosses the "static physics line shape" -- (cpSegmentShape) without affecting the collision of it..
I works fine with polyphase instead of line shape.. but that will be more better if i can use line shape also ..
Can anybody having idea to solve this ?
@JonKean :
I have downloaded the framework i putted it on my project.. but it seems like "New Physics Framework and Different too.."
Any PDF or documentation is available ?
tato123
Member
I'm not sure what you are referring to when you mentioned polyphase? I found some articles on electricity and I assumed maybe you were talking about wave generation?
I didn't end up posting the code last night because I found a bug where if I put a large amount of physics objects on the elastic shape it would eventually "pop" and box2d would end up going crazy and crash.
I'm still at a loss of how to actually apply graphics or texture the physics objects. For now I've been using box2d debugdraw to visualize everything. The only solutions I've thought of so far are creating a custom callback for the debug draw and render a wave on top of my physics bodies. Only problem I see is that all objects in the world would want to use the callback and I'd have to ignore everything but the bodies that are constructed for the wave / water effect.
Other solutions would be applying a large particle for each circle body and blending them together or creating a texture2d and creating a new ccgridaction that would update as part of the physics steps. Any suggestions?
tato123
Member
****sidelining this effort****
Given how unnecessarily difficult this turned out to be considering how small the code was, I've decided to branch this out into creating an IDE similar to mekanimo but for Mac. I've already started development on it as of last week and have made a good bit of progress.
I'm hoping to not only provide a workbench to create physics objects but actually looking to speed up several tasks such as level design with poly mapping physics to textures so that I can actually design levels from the work bench along with drag and drop physics objects and export to xcode as code based around the cocos2d framework. Essentially a game editor similar to what I'm used to working with for 3d games. It's ambitious but I've architected what I think will be a pretty solid solution and hope to have a tool ready in the next month or two to speed up my game development.
Started discussing in this thread
http://www.cocos2d-iphone.org/forum/topic/9064
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