Intro to Masking to Create a Realistic Fire Simulation with SimsUshare
Of course, you can put several elements onto the screen at the same time, and in this situation we have the two plumes in the fire on side A here and the smoke and fire on the roof. What happens, though, if we want to make it look like it’s all coming from the roof or the opposite side, the Charlie side? If I go back here now, I have a sort of smoke, I can actually put it up here on the top but I’m not really going to be getting it very close to the roof. It’s still not going to look like it’s coming from the other side. So what I’m going to be doing is using a technique called masking and with masking, there’s a special tool here, a little bit more advanced than the others called the mask, which is in the utility section.
When I click on mask, and this takes a little bit of practice, it comes up with this big handle and a square. Now, the mask is going to let me mask out certain areas of the picture. So let’s say that what we want to do is make these plumes are coming from the roof or possibly behind the building. So I’m going to mask off the front of the building. I move the square to where I’d like to start, and now what I’m going to do is draw the outline. So I use the options, the properties for the element and I can see here mask boundary. When I click mask boundary, it’s now going to give me little circles here that I can drag where I want to actually set the boundaries of this masking region.
Now, if I want to extend the line over here, now it’s very hard to see where the roof is. That’s why there’s a switch on the bottom that says hide other elements. If I click yes to hide it, now it clears that so I can actually see the nice roofline there. These buttons on the side, if I wanted to add extra points, I could just go click on the add, and then click where I want to add it. You’ll see it will add extra points there. If I want to remove a point, I can use the minus, and if for some reason once I get a lot of points I want to reset it back to a square, I can use that.
So now, if I don’t hide the element anymore, you’ll see that this is now what I’m trying to mask. Now it doesn’t know that I want to mask those yet. I have to tell it which things to mask, and each mask can handle multiple elements, but an element like a smoke can only be masked by one thing at a time. So if I go here to the properties, the pencil, and I say which to mask, it’s going to give me a list of all the different elements. So I may or may not want to mask them all. The ones that I want a mask, I basically just say, I click on yes or I move the switch over. Now what I’ve done here is I’ve set all the different elements to essentially, let me go back to take a look––I basically said mask out this area inside of the blue line. So now when I do the play, I get a very clean line. Actually you can see in here I didn’t do such a good job in the front, so that little front smoke is showing up there. But you see I get a really nice clean line on the top of the roof.
So masking is really essential for getting the dimensional feel of it. And points and the which to mask is all going to be something that you get through practice. Very powerful technique, very useful, and once you get the hang of it it’s really not so difficult to do.
One last thing that I should mention, when we actually go here to edit a mask and you click on the big diamond to edit the mask, and we say which to mask, you’ll notice that there’s a lot of names here–BrightFire, GreyTurbulent, GreyLaminar––and once you have a bunch of elements, it may be hard to know which is which. For that purpose you can actually name the different elements. If I click on an element, let’s say now, I’m getting out of the mask editing and I click on one of these elements. Now it’s saying “Editing Element GreyTurbulent.’ If I want to call that something other than “GreyTurbulent1,” I can go to menu, rename, select an element, and I can say something like “4th floor right window smoke” or something, and I when hit okay, now if I actually see ever here, editing 4th floor right window smoke, and when I actually go into my masking, if I go back over to that, let me go back to edit my mask, you’ll see which to mask, and 4th floor right window smoke is going to be the one right there. Much easier to know which is which.