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- [Instructor] Last week we saw how to perform a boolean subtraction or intersection on solid models and porting it into 3DS Max using the body cutter object. Today we'll see a similar workflow in which we can combine or perform a boolean union on solid models using the join bodies object and once again, I've got a watch model provided by Gabriel Corbett of TigerIndustrial.com and I've hidden some of the parts of the model so that I can focus in just on the watch face here. I want to combine all of these hour markers into a single object and that way I'll be able to manage my scene a little bit more easily and apply materials to just a single object. So I want to select all the objects and I want to join. An easy way to do that is to select by name, use the keyboard shortcut H to launch the select from scene dialogue and then select hour 01, hold down shift and select hour 12 and click okay. And now all those hour markers have been selected. Go over to the create panel and in geometry, from the pull down list, choose body objects and click join bodies and that's really all there is to it in this case. We're not really doing anything except combining all these objects. I can right click to exit out of that tool and with that object still selected, go over to the modify panel and we have some options here for the operation, but because none of these operands are actually touching one another, changing the operation will not actually have any effect. So that's all there is to that. Now that's a single body object and I can apply materials to just that single object. I want to go just a little bit deeper into joined bodies in order to illustrate the procedural or perimetric nature of the body object itself. I'll reset the scenes by going to file, reset and I'm not saving my changes this time. And I just want to create a couple of primitives for illustration purposes. If you've used standard primitives and then convert them to body objects, then you'll be able to change the parameters and also start the body object's tesselation separately so that's kind of a clever work flow. Let's make a torus. Now click on the torus button. Click and drag in the perspective view and that sets the first radius. Release it now and drag it again to set the second radius. Click to complete that torus and let's also create a sphere. Click on sphere and just drag to create a sphere that overlaps the torus and right click to exit that sphere creation. Now let's convert these two primitives to body objects and join them together at the same time. Drag a selection rectangle to select them both, go back up to the create panel and once again, from the pull down list, choose body objects and click join bodies. And now we see that they have indeed been converted to body objects. We can see that in the wireframe views, we're seeing just the curves. Let's go over to the modify panel and in the viewport display settings, set the display option to mesh and also in the perspective view, press F4 to show edge faces and now we can clearly see the tesselation of that body object into polygons and if we go over to our operations here, now if we change this up, we'll actually see some effect. That'll be clearest here in the top view if I zoom in a bit there. You can switch the operation over to boolean union and that's going to combine the volumes and remove any of the excess polygons inside those two volumes. We can see that we've got some tesselation over here at the area where those two volumes join. And of course, we can change up the parameters in either the viewport display settings or the rendering approximation settings as we saw in the previous movie. I can switch the viewport display settings to a fine tesselation and now we're getting a very smooth result there. But what I really want to illustrate here is that if we start from basic standard primitives, then the mathematical parameters of those primitives would be preserved after the objects have been converted to body objects. So let's investigate. If we go up to the modify stack, open up join bodies and select operand, now we're in operand cell object mode. Open up the operator parameters rollout and let's select torus001. Up here in the modify panel, we can see that torus is listed now and if this were a boolean object, we can just click on that and then access the torus parameters. But for the body object, it doesn't work quite so simply. If we want to access those torus parameters, we're going to have to extract the torus to a separate object. All we need to do is click on extract cell or extract selected. And now that's been copied off to a separate object. Let's exit out of operand cell object mode and then dolly back into perspective view. We want to select the newly created torus, click to select it, grab the move tool, and just move it out of the way and now if we change the parameters of that torus, because it's an instance, we will also change the parameters of the body object. For example if we change radius two, it'll reduce the thickness of the torus and notice that the tesselation here is adaptive. As we change the radius, we are seeing the edges move around on the model. But even more interestingly, because this started out as a standard primitive, some of these parameters that have to do with level of detail are not going to affect our body object. For example if I change the number of segments in the torus, if I drag that down, I see that I can bring that down to only three segments and I've got a very super rough approximation of the torus. But because it started out as a standard primitive, the mathematical representation of that torus is preserved in the body object and so although the radius parameters that affect the shape do instance into the body object, the level of detail parameters such as the number of segments and sides do not factor into the tesselation of the body object. All right that's a little bit about how parameterization works for body objects specifically in conjunction with the joint bodies object type.