Mirror | rorriM

Is there such a thing as a mirror that literally reflects in real-time what is in front of it?

There was (a few viewer editions) back a viewer that had in it's debug settings the ability to have real-time dynamic reflection render on prims set to shiny. Unfortunately, this never made it past that stage and in fact was removed from later viewers.

It was a major resource hog and didn't reflect at the correct angles. In other words, standing right in front of the prim did NOT cause you to be reflected in that prim. It was only when you moved the camera at an angle to the prim did it finally reflect. This might have been why it was scraped.

So... sorry, not really.

Nope.. only can use tricks to make mirrors, and then only static objects (or specially-scripted dynamic ones).

For example, if you wanted to make a mirror-polished marble floor in a mall, where you could see a faint, but distinct reflection of the structures in the mall, you would make your mall build, then build a complete mirror of it "underneath" the floor, then set the floor to partially transparent. That way, you get a simulation of the "parallax effect" that a real mirror would provide.

The downside is a HUGE waste of prims, just for a simple effect, but it sure can look neat.

I experimented with the "Dynamic Reflections" option for prims when it first came out, and yeah, it never did work right. For one thing, it never reflected *anything* that was within about 5 M of the surface. And the angle of incidence and reflection was always way off. I'd have to move my camera way off to one side to see my avatar reflected in the surface. Seeing oneself in the surface via Mouselook was always an impossibility, regardless of angle to the mirror.

As stated earlier, it really lagged you down, and it never worked right, so they scrapped it.

The reflections in the surface of Linden water are different. It's relatively simple to define a single plane sim-wide, and render reflections in that surface, or even add ripples. So you can look into a pool of Linden water and actually see a distorted real-time reflection. But doing reflections on any random surface, at any random angle to the viewer, and having a potentially infinite number fo such surfaces in a sim at an infinitely variable possible set of positions was a calculation nightmare.

For real reflective surfaces, your frame rate would drop by:
F/(r^2+1)
F -> Frames per second
r -> the number of reflective surfaces

If you can limit reflective surfaces to just one (no recursive iterations) then the frame rate will only drop by half.

Fake reflections like the water use a copy of the sky bitmap that is then drawn on select portions of the water in much the same way as an alpha layer would work. This keeps it blurry and uses a static bitmap so no need to generate what is in view.

In short, reflections are a technical nightmare at the current level of technology.

Actually the water makes per pixel reflection when cranked to max.

Mirrors were fun while we had them, though.

Well.. Isn't every new release of the client just another episode of "Smoke and Mirrors, by Linden Lab" ?

Since when is it a waste of prims to properly build the effect you want? I suppose making a wall with a separate prim for a window is also a waste of prims, because you want to avoid the alpha-on-alpha sorting problem that plagues all 3-D software?

I disagree wholeheartedly. If somebody wants a specific look and does what it takes to build it, not a single prim in that build has been wasted, even if it triples the # of prims they'd use to create their build minus that special effect.

1) Prims are probably the tightest resource in SL.
2) The wall you are speaking of is *A* prim. Not even remotely as prim-intensive as a mirror build.
3) The people who have built such things as I described have said THEMSELVES "I know it's a huge waste of prims, but it sure looks neat". <-- That's almost verbatim what I was told.
4) It's not a difficult trick to accomplish, but you don't see it used much. Why? It's not generally worth the extra prims or hassle. For a 10-stall mall with a mirrored floor, you could have had a 20-stall mall. *shrug*



You're free to. I will freely admit that I waste prims for effect, too.

Perhaps you are disagreeing with the sense I am using the word "wasted".

It's not a waste in the terms of pointless usage of prims, such as one would find in a newbie's untutored attempts at building, but in terms of prims on land.

While it is a pretty neat effect, you have to take into consideration that it is a single effect. In my case, that single effect is not worth the cost of prims. I'd rather maximize my prim count in anyway I can.

I like the title of this thread.

Why can't the same effect that's working on water be used on a prim? (o.o)

It's not really the same effect. If you stopped the rippling, you would see that the reflection quality is poor. Also, notice the performance hit between full water reflections and off. That's just one mirror, of low quality. Now, imaging 20 prims in a scene, all mirror-surfaced on all sides.

Can you see where this is going?

No. The distortions on all the mirror prims make it too hard to see.
























j/k

Water reflections are very low impact on my 8600GT setup. I run Ultra mode with Impostors off, AF, and 4xAA. It would still be fun to something like water reflections implemented on a prim. Even just to see it happen. (^_^)

Anyway, didn't one of the shadow drafts have a claim that real bumpmaps and reflections were implemented? (o.o)

It would be very kewl to have the option of having rippling-water-reflection on a prim, I think.

Reflections on the surface of Linden Water:
* Only one such surface can exist in the entire sim.
* You never have to deal with a reflection of a reflection, repeated ad nauseum.
* That surface is always flat, and perpendicular to the Z axis.
* The actual reflected image is low rez, and the poor quality is masked by the ripples.

Reflections on the surface of any prim, that work like Linden Water reflections:
* A potentially infinite number of such surfaces can exist in entire sim. And can be positioned to reflect each other.
* That surface can be any shape, and any orientation to any axis.
* The actual reflected image might still be low rez, and the poor quality is masked by the ripples. But most people would want to be able to turn those ripples off and would expect a crisp reflection.

As soon as you allow more than one reflective surface, you start multiplying the complexity of the calculations needed to render the scene. In 3D Rendering applications like Poser and DAZ|Studio, you can set limits to how many reflective surfaces a ray-traced line of sight can reflect off of before it stops trying to calculate the results. But even then, somethig simple like three mirror-reflective spheres in a room, where each sphere reflects the room, and the surfaces of each of the other spheres, can get horribly complex and slow to render even with a limit of two reflections per ray.

I reckon we'll get proper reflections one day, along with dynamic shadows. After all we get real, complex and moving reflection on Linden water already.