I am using the particles system to make “bullets” fire from a little aircraft. The aircraft follows a path and does a few turns. However, when the craft turns, the already fired bullets turn with it. It looks very strange. The bullets are rotated in the same direction as the aircraft although they were fired some time ago and are still moving in the correct direction.
Is there any way to fix that, or is it a bug? Am I doing something wrong? The bullets fire from a particle system “server” that is parented to the aircraft.
If this explanation is strange, perhaps I could upload a small animation to make it clearer.
Please help…
Oh, and another thing… is it possible to have an animated backdrop in the animation? I know how to use a still image, and I also know how to attach an animation to a plane and use it as a background screen in the animation, but there are certaing things that does not works as I want and I need to have a real animated backdrop.
You can use an animated texture on the world in the same way as you do on a plane.
If for some weird reason that doesn’t work, try putting your scene in a big sphere, put tha animation on that, and choose Shadeless and Win mapping in the materials.
Thanks a lot for the help on the animated background. I’ll test to add the animated texture to the world instead of to a plane.
You see, the problem is (was? ) that I intend to use a ground plane where some objects can cast shadows. The ground plane is only visible where it receives shadows (great feature of Blender!!). However, the problem with the backdrop is that if I use a “normal” backdrop that is set among the rendering buttons, it looks fine but I can only use a still image. If I, on the other hand, use a plane as backdrop, I can have an animation there, BUT the ground plane is rendered in front of the animated plane, resulting in a complete black lower part of the animation. Hope that the animated world works better there.
Anyway. Back to the problem with the particles.
The “real” problem is that I use an object (duplivert) as particles and that is, just as usual, parented to the particle server, which, in turn, is parented to the aircraft. Now, as the aircraft turns and the particle server spits out bullet objects, those bullets turn with the aircraft. It really looks weird… I have tried the “Vect” button, but that does not seem to fix it. Any more suggestions?
I’ve duplicated your problem- there is a very simple way to solve this. I’m assuming your particle is a dupliverted object that is parented to the emitter. Therefore when the emitter turns, the dupliverted object turns with its parent.
If you create what’s called a ‘vertex parent’ the child will not rotate with the parent, but it will still work with dupliverts for an emitter.
*Simply select your child, and then shift-select the parent.
*Hit TAB to enter edit mode.
*select a single vertex
*press Ctrl-P and it should say “Make vertex parent”
*Exit edit mode and see if it worked
Thanks again… but… sorry, still not the way I need it to be.
Do like this:
New scene, let the original plane be there (will be used as particle emitter)
Create a new plane and scale it down along ONE axis so that it becomes a thin rectangle
Parent the thin rectangle to the square plane
Add a particle effect to the square plane. Check “Dupliverts”. Set the number of particles to 30 or something, and set the “Norm” to amost 1.0
Add a Rot key to the square plane
Go to frame 50
Add a new Rot key to the square plane
Animate and see my problem live… sob, sob…
You see, at the creation time of each particle, its rotation should be the same as the parent object. But, immediately after leaving the parent, it should maintain it rotation and not rotate as the parent rotates…just like bullets fired from a rotating gun.
Thanks for all the help on this, but it appears it can not be solved that easily. Does anyone know if it can be done with scripting? I have no experience at all with Python scripting.
I suppose I will have to add all bullets manually with paths and such. I had hoped I could avoid that because it will take so much time.
Theeth was right in his answer about using vector particles with the rot option enabled. Download this:
www.orst.edu/~dennisa/Blender/particles.blend
What I’ve done is parented the rectangle particle to the square emitter, gone to the animation buttons and hit the Dupliverts and the green ROT button. In the particle settings you need to make sure that you have the green Vect button clicked.
*Note: If the dupliverted object isn’t facing the direction you want it to, you’ll need to rotate it in edit mode. Pressing Alt-R to clear the particle’s rotation before you parent it to the emitter will make it easier to tweak the direction. Sorry if this doesn’t make much sence. If you have any questions just ask.
The example file looked precisely the way I want it to look.
But…but…but…
Here are my problems:
When I try to copy what you have done in my own file, it does not work like that…?? If I parent the bullet to the entire square, it always rotates with the square. If I parent the bullet to just one vertex, it NEVER rotates.
Try UN-selecting the Rot button in your example. It works anyway. (At least for me… I have v 2.27). What on earth is it that you have done??
Just a random thought - try clicking “Recalc All” in the particles settings. If you added the Rot IPO after doing the particles it would have odd effects.
) that I intend to use a ground plane where some objects can cast shadows. The ground plane is only visible where it receives shadows (great feature of Blender!!). However, the problem with the backdrop is that if I use a “normal” backdrop that is set among the rendering buttons, it looks fine but I can only use a still image. If I, on the other hand, use a plane as backdrop, I can have an animation there, BUT the ground plane is rendered in front of the animated plane, resulting in a complete black lower part of the animation. Hope that the animated world works better there.