Faded edges, animating halos and particle systems

(medains) #1

1 - Faded edges

I’m trying to get an effect that has a cylinder with soft edges (ie the ‘edges’ as visible to the camera blend into the background)
I’ve tried to do it with a ‘blend’ texture operating on the alpha, but I can’t get the settings right.

2 - Animating Halos

I want to create an animating in which the ‘lines’ of a halo move from frame to frame, I know that I can acheive this by changing the ‘seed’ of the halo lines, but I can’t set a key on this material variable… any ideas how I can do this, without animating frame by frame by hand?

3 - Particle systems

I want to put together a moving line of particles, with very minor random jitter. Using a single face mesh and a ‘norm’ value of 2, I’ve almost got what I want (although a higher initial speed would be nice), but the jitter
occurs in waves because of the way the particles are emitted from the face. Thus the line appears to ‘pulse’ when animated.
Any ideas how I can make the jitter more random?

Also, if I apply a random speed, that speed is applied in all 3 axes, is there a way to constrain it to being in the direction of the normal?

(S68) #2

What you are trying to do is called ‘Volumetric rendering’ and Blender does not support this. It is what you get with a transparent cylinder which is not perfectly transparent.

You can fake this by creating a single line, subdividing it wildly and assigning an Halo material.

halo size is the cylinder size,

Hardness and aplpha controls fading.

Of course you are in trouble at the endings.

No, sorry.

You’re really out of luck :stuck_out_tongue:


(theeth) #3

I think I have an idea that could work for this, I’ll try to do an example blend tonight.

I think that if you put Seed different than 0, the positionning of the lines is based on the position of the halo, so they would change over time in the case of moving particles.

Try looking in the Python forum for Dynamica, it`s your only hope.


(medains) #4

For 1) I’ve tried a line of halo vertexes… I either end up with the edge not fading smoothly (too much add) or the individual vertexes breaking being visible… I guess it’s the best I can do.

For 2) I’ve worked out how to do it.

Object 1, single point vertex with halo material.
Object 2, single point vertex with same location etc… as Object 1, add a particle emitter with settings of
Tot: Number of lines wanted * number of frames
Life : 1

Object 2 creates random ‘lines’ from the particles, not quite as good as the lines halo effect, but good enough for the animating.

If you give both objects a nice red colour an add value of 1, and voila! a trek-style photon-torpedo

I think that I’ll write this up as a tutorial :slight_smile:

For 3) I think I’m gonna give up

(Rhysy 2) #5

For number 3, select the object, go into edit mode, select all the vertices, then go into the edit buttons and press the hash button. This should make the particles be emmitted from verticies in a random order and get rid of the pulse problem. To make their speed more random, the particlerite button/slider might help, but I’m not sure.

Where is this “seed” value of which you speak ? Sounds useful, even if not in this instance.