From the course: Modo 2019 Essential Training

Destructive vs. nondestructive - MODO Tutorial

From the course: Modo 2019 Essential Training

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Destructive vs. nondestructive

- [Instructor] In MODO there's two completely separate approaches you can take to modeling, the first is what's known as destructive modeling and the second is called procedural modeling. So with destructive modeling you enter one of the three component modes, polygons, edges of vertices, and you interact directly with the structure of the model performing such things as bevels or extrusions or cuts. Whereas with procedural modeling, you create a stack of what are known as mesh operators which you can come back and edit at any time, even after you've completed the modeling operation. So the main difference between the two approaches is that with procedural modeling you can always come back and edit any of the parameters in your stack at any time whereas with destructive modeling, once you've dropped the tool that's it, you can't come back and edit any of its parameters. So you might be wondering to yourself why you would ever use destructive modeling, it sounds like procedural modeling is much more powerful and flexible. Well, it's not quite that simple because destructive modeling is also very flexible and powerful in its own right, and the main advantage it has over procedural modeling is that it allows for a much wider range of forms and shapes. So for example if you were going to model a complex organic shape, say a human being or an animal of some description you would have to use destructive modeling simply because procedural modeling wouldn't have the range of tools that are required to create those kind of shapes. So let's have a look at some actual examples, I'm going to create the same final form using the same steps, first of all destructively and then procedurally. So in an empty mesh item in polygon mode I'm going to activate the cylinder tool and I'll place my cylinder 200 millimeters in the y, with a radius of 500 millimeters in the x and z and 200 millimeters on the y. I'm going to make sure my polygon type is set to Catmull-Clark, and I'm going to make sure my top and bottom are set to quad grid and I'll set my edge rate to zero and with that done I'm going to hit apply to create my cylinder and drop the tool. So with my basic shape now created I can do some destructive modeling. I'm going to select these four polygons in the center of the cap, and then hit shift up arrow to extend my selection, I'll then switch to the polygon tools and I'm going to activate the polygon extrude tool, and click once in the view port to activate it, I'm going to set my extrusion to be two meters on the y with 10 sides and with that done I'll drop the tool. I'll click an empty space to clear my selection and then I'm going to switch to the deform tab and I'm going to activate the bend tool and click once in the view port to activate it. I'm going to make sure my action center is fully zeroed out so that it's at the origin, so let's just enter a value of zero everywhere here, I'm going to extend my bend two meters on the y and I'm going to set the angle to be -90 in z, with that done, I'll drop the tool. And so that's the basic shape created using destructive methods. I'm now going to create exactly the same shape but using procedural methods, so let me just switch to item mode and activate the move tool and I'll just move that slightly to one side. And I'll hover over the item list and hit the n key to create a new empty mesh item. And then I'm going to click this icon here to open a mesh operations view port, and from here I can start adding mesh operations to my new mesh. And mesh operations are organized in a stack working from bottom to top, so let's start with a first step which is creating the cylinder. I'm going to click on the add operator button and I'm going to search for the cylinder primitive, once I've located it I'm going to double click it to add it to my stack. And then it's simply a case of matching the values that I entered earlier, so I'm going to set the y position to 200 millimeters and I'm going to set the y radius to 200 millimeters, I'm going to make sure that the polygon type is Catmull-Clark, I'm going to cap the top and bottom with a quad grid and I'm going to set the edge rate to zero. Next I need to extrude the faces along the top so I'm going to go to add operator, I'm going to search for extrude, and then I'm going to select polygon extrude from the list. But before I can drag the extrusion handle I need to define a selection, and we do that by means of a selections operator, so I'm just going to expand the polygon extrude mesh operation and then expand the selection section and click on add selection. I'm going to select the select by index operation double click to add that to my stack. And now I can switch to polygon mode and select those four polygons in the center, hold shift up arrow to expand my selection and then once that's done I'm going to click the set button to set that selection. Then I'll return to the polygon extrude operation and I'm going to extend it two meters in the y with my sides set to 10, just like I did before. And now I need to add the bend operation, so once again I'm going to click on the add operator button and this time I'm going to search for bend, once I find the bend effector I double click to add it to the top of my stack. I'll set the angle to -90 and the y to match my previous bend and the length to two meters, and just to match the rotation of the first mesh I'm just going to rotate that 90 degrees in the y. And so we've now created two more or less identical meshes using completely different modeling methods, but the benefit of the procedural approach of course is that I can go back into the stack and alter the parameters, so for example, if I want to change the angle of the bend, I can just do that, or if I want to go back a step and go back to the extrusion and maybe change the number of sides let's increase that to 20, you can see that it's very simple to do. However with the destructive mesh, it's simply impossible to go back and alter any of the parameters that were previously applied. However, destructive modeling does allow you to create a much wider range of forms. So the rule of thumb is, if you have relatively simple shapes, especially mechanical shapes where you need the flexibility to be able to go back and alter parameters on the fly, then use procedural modeling, but if you need to create complex shapes, especially organic shapes but even complex mechanical shapes, then destructive modeling is going to be the way to go.

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