Join David Andrade for an in-depth discussion in this video Hide geometry with masks, part of Blender: Tips, Tricks and Techniques.
- [David] Whenever you're working in Blender, you sometimes want to remove geometry but not really remove it. You could go ahead and make duplicate files or duplicate objects and hide them, or maybe you're just working on an object and you just want to hide something really quick just to see what it looks like, but you don't necessarily want to delete it. Well, Blender gives you a really, really simple tool to use, and it's called Mask. Let me show you. Let's go ahead and delete everything here. I'm gonna hit A twice, X Delete.
I'm gonna pull this open a little bit. Shift + A, I'm gonna make a monkey. I'm gonna hit Tab + S to grow my monkey a little bit. W, subdivide smooth. Let's turn the number of cuts up to two. That way we have a lot of geometry. Now let's come over here to Object Data, Vertex Groups, make sure you're in Edit mode, hit Tab if you need to. I'm gonna come up all the way up to the top here, select this vertice. If you're not in vertice mode, Control + Tab to switch to it.
I'm gonna go to Select, Side of active. If for some reason you don't select one half of it, just play with these settings until eventually you do. Should be X-axis. There we are, and let's come over to Vertice Group. I'm gonna say side. Just double click to rename it, then click Assign. Hit A to de-select everything, let's do that again. Let's pick this vertice right about here. It doesn't have to be exactly this vertice, just more or less something like that.
Select, Side of active. In this case, I want the front of the head, so let's actually go Y-axis, and, negative axis, there we go. Plus sign, double click, face, assign. And then let's make one more for fun. I'm gonna type in, random. I'm gonna hit A to de-select, C to make the little circle selection. Just paint anything randomly, doesn't matter what.
Enter. Assign. All right, now, tab out of Edit mode. Go to Modifier. Go to, Mask. And if I bring this open a little bit, under Vertex Group, I can click here, and go to face. And look at that. I now have just a face of a monkey. The cool thing about this is that, if I turn these off really quick, you can come up here and you'll see my faces, is at, in my case, 45 hundred.
Yours might be a little different, but more or less. 45 hundred. Turn these on, and with the face group on, my face count goes down to 2200, at least in my case. Your case might be a little different in terms of the specific number, but the point is, Blender now has less geometry to deal with. That's less overhead on rendering, and more importantly, makes your scene go a little bit faster, too, so you can see the power of using a mask.
It's just a very simple way at hiding other geometry, but if I hit Tab, it's actually still there. I can hit A and do anything I want with it, tab out, and I'm not affecting anything else. If I want to, I can hit this little button here to invert it and see what the inverted version of the face is, or I can switch to random, or side, and again hit Invert, and see how that affects everything.
Now, I'm actually going to tab and move this crazy vertice that I moved by... More or less lining it up, there we go. Okay, so let's click the X off of random. Let's hit one and five on the numpad. If you don't have a numpad, View Front, View Ortho. Now hit Shift + A, let's go to Armature, Single Bone. Let's go up to this little man here, click on X-Ray.
Tab to go into Edit mode. Select this little top part. You can zoom in to see it better. G, Z. Move it about to the top of his head. E, drag it to one ear. Select the little top part again, E, drag it to the other ear. This time, select the bottom part, E, and drag it to about his mouth. Okay, now, if I click on each of these bones, I can go to Bone Properties. This middle one, I'm gonna call Center. This bottom one I'm gonna call bottom.
This one on monkey left, I'm gonna call left, and on the monkey's right, I'm gonna call it right. Okay, now Tab to get out of that. Select the monkey only, Shift + Select the armature. Control + P, automatic weights. Select the armature. Pose mode. Select one of these really quick, doesn't matter which. And hey, I'm moving the monkey.
Now just put it in a random position while in Pose mode, doesn't matter what. You can move it, do whatever you need to do. Now select the monkey modifier, and under Mode, switch it to Armature. Under Armature, pick Armature, and look at that! Now, everywhere where I select a armature bone, in this case, the bottom, in this case, monkey's right, or monkey's left, you can see that Blender is only showing the vertices I currently have selected that are weighted to this very specific bone.
Now, you're probably asking yourself, well, how useful is this? It's actually incredibly useful because I can come back to the monkey, hit the Invert tool, select one of these bones, doesn't matter which, and I can see which vertices are not being affected, and what if I needed a vertice right here to be affected while using this mask method? I can quickly see which vertices I need to fix, and/or, if I come back to this monkey, turn off inversion, come back to this bone, start moving stuff, I can see which vertices are being affected and thus get a better idea of what I'm doing and what I'm working on.
So, masking is actually really really handy. Just be careful you don't hit A to de-select everything or you won't see anything. But masking is super duper handy, and I highly recommend you play with it, because it is a very cool modifier to use inside of Blender. Until next time, this is David for Blender's Tips, Tricks, and Techniques.
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