During the creation of this video http://youtu.be/S9LtDzTeb_c?hd=1, I came up with a solution for the limitations from blender particle’s lack of support for animated texture, collision detection, animated vertex group and mask modifier. Back then, I did not have the time to make it better. So, now this is the first test of many to come, in an attempt to create a good method for particle emission from collision detection. I hope people here can learn my method, give me suggestions for a new one or help me improve it.
It uses most of the method I explain in here http://www.youtube.com/watch?v=EgjW0MOalg4&hd=1 but the mask modifier goes on the plane, not the cube, and there is no remesh.
I don’t have the time right now, but my next attempt will be using the dynamic paint to create texture and a displacement effect on the water, but only that, since blender won’t allow the dynamic paint to affect the particles. Something like this
THE METHOD SO FAR
1-create the ocean modifier or the part of the collision that will be still. and the other object that will collide.
2-create another mesh, roughly the same size and shape of that. It must be with a big subidivision of evenly spaced, this will be the collision detector. Create a vertex group, apply a vertex weight modifier to it, linked to the other object that will collide, so that when it gets close to the ocean, it will get a stronger vertex weight.
3-create another object that will go with the collider in movement. Maybe, parent it to the object. And apply a shrink wrap to the last object. this will be the one emitting particles.
PROBLEMS
There are many problems on this method:
-Slow - blender calculates a ocean, then another mesh with a lot of subdivision, then weight proximity, then shrink wrap, then another mesh, then… what I want to say is: this will make big simulations and complex scenes almost impossible.
-far from exact - The collision detection is limited by the subdivision or remesh resolution of the object. Finer simulation will make it more visible and require even higher subdivisions.
-No current way of influencing most particles direction and intensity. The force of the particles and its direction should be defined by the direction and violence of the impact. I “solved” this in my wave using textures controlled by the Z axis. There it was possible because usually the higher in the wave, the stronger the collision. But what about a boat? It will emit particles the same way, if it is stopped or moving. Just the moving of the object itself will influence the direction and force. But not how is it impacting the water or anything.
So… is anyone interested in this?
I filed bug reports regarding the lack of support for animated textures and mask modifiers and weight proximity modifier. They told me blender particle is not meant to do this right now. Those are known issues. So… I don’t think a sollution is going to come from the developers right now. It should be in our hands.