We're going to add another tool to the net to give us a different type of visual realization. Bring the VPE up to the top and place a Realization: Isosurface module on the net. Where will it go? You have several logical possibilities this time.
I'm going to think out loud, hopefully, like a new user:
NU: We could put Isosurface before Import. No, that won't do; how could we make an isosurface from data that doesn't exist yet?
Teacher: uh huh. Very good.
NU: We could put Isosurface after Image. Hmm, no. That makes no sense: how would we see the isosurface object if the isosurface creation operation took place after the image was already drawn in the Image window?
Teacher: so you were paying attention!
NU: I have an idea: let's put it beside AutoColor, then similarly to what we already did with AutoColor, we can hook up Import to Isosurface and Isosurface to Image. Or can we? Teacher: how do we get Import to feed more than one module? Uh, oh, I bet we have to put another Import module in if we want to do that. Hmm, maybe we need another Image too.
Teacher: OK, whoa, let's stop and investigate that last one. I did say earlier that a feature of DX is that it allows multiple Import modules, and I also said you could have multiple Image modules where necessary. But that would be a bad idea here. If you want a copy of a data set that has already been imported, it's very easy to do.
Output Wiring Rule: Yes, you can hook another wire (as many as you want) from a module's output to other downstream modules' inputs.
If you added another Import and imported the same data file twice, you'd be using up memory unnecessarily: it would work, but it's not a good idea.
Let's take this a little further. Put the Isosurface module next to AutoColor. Rearrange your modules as you like, to make room. Now drag another wire from Import's output tab to Isosurface (which tab do you think it goes to?). As you see, you can have more than one wire coming out of an output tab. Each wire carries an identical copy of the output object to the different inputs.
|
 |
Optional: View this Technical Aside if you want more detail on this subject; the information is not required to understand the upcoming material. |
Pretty handy, eh? Now you're feeling smug, so you try to hook up the output of Isosurface to the input of Image. What happens? This time a little Error dialog pops up and informs you that you cannot do that since the input is already connected (to AutoColor, of course).
Input Wiring Rule: You may not connect more than one wire to any input in DX, nor can you connect a wire to an input that is turned down (because you've set a value inside the CDB).
Now why does it seem inconsistent? Think about the implications of permitting multiple wires from differing sources to connect simultaneously to a module input. What's a module to do? It's one thing to share copies of the same output, but very difficult to have to wade through what could be a very disparate set of inputs. It would be a pretty hard problem to solve in a general way. So it's not permitted.
You could add another Image, but then the two objects would not be displayed in the same space, making it difficult to perceive how they relate. This is one of the powerful features of visualization: visual comparison.
