View Full Version : How to reveal a trace along a path...

11-18-2017, 08:22 AM
OK, here's what I want to do.

I'm going to have some stylised orbits for inner planets, simple cirecles around the Sun, with small balls where the planets are.

I want to show a trajectory between the planets, passing close and being deflected.

Now it should not be too difficult to make it as a 2 point poly chain in modeller, and extrude along the path to make a chunky easy to see tube along the required route. But what I would really like to do is reveal the trajectory gradually, so that at first you only see the part near Earth, then it extends showing the trajectory as time procedes.

Anyone got any ideas for an elegant way to do this?

11-18-2017, 08:47 AM
I'm going to have some stylised orbits for inner planets, simple cirecles around the Sun, with small balls where the planets are.

Solar System plugin is generating entire animated Solar system

To make traces of object,
clone object,
then use Extended Spot Info -> Extended Item Info -> Clone Index as source to Gradient controlling transparency or other way fading away.
(from TrueArt's Node Library http://www.trueart.eu )
In Motion Options, add Nodal Motion, and use Clone Index to read what item had position couple frames ago.

11-18-2017, 08:53 AM

We start from empty scene..

11-18-2017, 10:49 AM
Thanks, plugin looks cool, but that's not really the bit I needed help with...

11-18-2017, 11:02 AM
I use Particles and HV for tracing paths quite a bit, but it may not meet your needs. Sample scene attached, using a simple circular orbit.



The basic idea is to put a Null on the trailing edge of the Planet's diameter, add an FXEmitter in the Properties=>FX tab, have it emit 60 Particles per second (2 per frame, more if needed depending on the speed and radius of your orbit), make sure the FXEmitter etc=>Parent Motion is set to 0%, the Life Time is 0% (they don't vanish over time), and the Resistance is set to 10.0 so they stick right where they're emitted.

Then, the Hypervoxels are tuned to the scale of your planet / scene, give whatever color you want. In this scene I used Sprites, turned off all Lights so the planet doesn't cast a shadow on the trail, and set the Luminosity to 1000%. The HV size drops down over time using a Gradient on the Particle Age, but could remain constant, of course.

I couldn't include the images used for the Textures in the attached GIF since they're too large to post.

Hope it helps!

11-18-2017, 03:41 PM
Weight map on a 2 point poly chain. This was my test with FFX, although you could skip that bit;

11-18-2017, 03:59 PM
I would also look in to particles and hv sprites, in this case I am letting the object itself act as base source to emitt particles from, and setting the emitter to object line helps particles to flow in a dense fixed pattern trail behind the object, though in this case I also added turbulence textures in the particles motion, you wont need as much particles as this nor as advanced.

Definitely also take a look at Mark Warners techniques, it may actually be enough.


11-19-2017, 04:47 AM
Thanks to all for the suggestions!