The only effect required in this tutorial is the amazing Alpha Threshold created by Animmaniac. (He's brazilian like me! \o/)
This is the final result:
Play it Here
First of all, create a new layer, you can name it how you want. In my case, the name is "Fluid".
This layer is where you'll create your Fluids.
Our Fluids are maked with metaballs, something like this:
Create a sprite with a ball of 0 hardness and a collision polygon as above. This is your metaball! Rename it to "Metaball" if you want.
It's really important the metaball be in the "Fluid" layer!
Now, add a effect to the Fluid layer, the Alpha Threshold:
It's really, really important the effect be in the Fluid layer, or it will not work!
If you clone the metaball (hold ctrl + left click) you'll see the result like below.
You can make a "inner shadow" changing the value of "Flat Colors = 1" to 0.
Congratulations! Now, just add physics behaviors to your metaball and you'll get your very own fluid!
If you want a realistic water fluid, set metaball's physic friction to 0.0001!
Thanks! If I help you, give me a favorite o/ !