Billboard Camera?

[skinnytorus]

Hi, guys.
I've been curious if I could build a setup similar to what is possible in Wz4 and called Billboard Camera. In short, I wanna be able to 'rendertarget' a mesh into a sprite and then replicate it through a particle system. The trick is that I want the sprites to show the original mesh at proper angles as I move/rotate the camera across the particles. What's the sMode way to deal with that?
Thank you.

[martin]

Hey !
Rendering on billboards with different angles is not possible so far, sorry.
You should use the instantiate modifier. That will instantiate the mesh X times, resulting in a bigger mesh. It's not on the trick you asked for, but the closest thing to it !

[skinnytorus]

Hi, @Martin!
That's a bummer. But, IMHO, the effect is really simple. As I see it, all you have to do is create a rendertarget for a camera constrained to only rotate around a mesh at a certain distance (while doubling the rotation angle of the main scene camera) and output it to a sprite render primitive. Perhaps some clever rigging could help?

[martin]

We're not sure about what you want, could you clarify: you'd want a particle on the left of the screen to display a different angle of the original mesh from another particle on the right of the screen ? Or all particles can display the same image that gets rotated regarding to the orientation of the main camera ?

If all the sprite can display the same image, it is possible by using local links - otherwise it's not.

[martin]

It would be cool if you have an example or video of that to help us

[skinnytorus]

OK. I will show you how it's done in wz4.
1) Grab the binaries from here.
2) Download my wz4 example file (billboard camera 1.zip (904 Bytes)).
3) Launch wz4 and open the attached .wz4. There you will see the stack - all self-explanatory

[skinnytorus]

P.S. Of course, the effect is not perfect in terms of perspective, but under certain conditions it allows to work wonders. You can spawn thousands of particle systems that way.

[martin]

I'm at a loss on how to run it haha
Is there a preview somewhere or do I have to run it using the player ?

[skinnytorus]

OK. More info here and here.
In fact I think you just need to install DirectX9 June 2010 redist.

Latest Community Edition (Wz4CE) binaries + all necessary libs are here, the player is here..

For the Wz4CE you will also need PhysX 3.3.1 PC SDK Core, but the Community Edition pack already includes all the DLLs you may need.

EDIT: If none of that helps, here's a step-by-step building tutorial: here.

[francis]

This solution should work:

• inside you SpritePoints, put a Compo containing it's own local camera + the 3d mesh
• create a link between the global camera's orientation and the local camera orientation (you can either expose a global "orientation" parameter and connect both camera's orientations to it, or directly create a link from the top-level camera's orientation to the local's camera orientation)

Didn't try Wz4, but probably the easiest way to make your point is to post an image or two

[skinnytorus]

Hi, @Francis.
Good to hear from you. Your solution is fine, but the render target camera doesn't update in real time and doesn't react to lights of the main compo. Find attached my attempt at the setup you mention. Since you don't feel like messing with Wz4 , I have a couple of screenshots to get across the idea.
rt1.compo (57.0 KB)

Perspective main cam view:

Top perspective main cam view:

[francis]

Your inner compo was not configured to take "RT Cam" as current camera. Try:

Also, enable depth testing for the Sprite Points:

And here we go:

[skinnytorus]

Cool! Thanks. I'll try that this evening and check back. However, a couple of questions still remain:
1) Should I instance lights in order to make the rendertarget and the rest of the scene be lit consistently?
2) How to feed more than one rendertarget to the particle system?

[francis]

More than one render target is easy, just duplicate the compo and put parameter "Sprite Points > Sprites > Interpolation" to "Nearest":

About light, it's indeed quite tricky and obviously limited due the way imposters work. I obtained the image above by disabling Point Light / Direction Light > Advanced Parameters > "Restricted to current group" and by setting Point Sprites > Auto Illuminate to 0%

[skinnytorus]

Yep. It works! Many thanks for the tip!
However there's a problem with lighting indeed. Besides, rendering shadows from sprites has an issue: shadows don't seem to respect sprites' alpha channel. Fixable?

[martin]

shadows don't seem to respect sprites' alpha channel

That's one limitation of Smode for now.
I'm creating an issue for it, and will see if it's long to fix. Will keep you updated !

[skinnytorus]

Thanks, Martin.
Looking forward to some good news on that soon.

[RBasile]

Hi,
We recently fixed the issue with the alpha in the shadow of the light
it will be available in the next release of Smode Designer ( 9.2 ) ( or in the Beta version )
Sorry for the time but it's better than never