What a Mesh

Surface Modeling in AutoCAD - my AU 2010 class - Part 3

Continuing with the surface modeling explanation, after some weeks of very intense trips. 

Select the LOFT command in the Create panel on the Surface tab, and then you can select curves for lofting. By using Ctrl, you can also select a surface’s edge. As usual, Ctrl enables access to subobject level, and in the case of a surface, to its edges. We need to select the edge, in order to get access to the option for continuity.

If we select a spline coincident with the surface edge, we can create the loft, but it will work as a G0, since the command does not detect the adjacent surface when choosing the spline. Once you finish selecting profiles, you will get several options. Let’s focus on Continuity.

The options for Continuity are G0, G1 and G2.

G0 (position) continuity means that there are no gaps, but there’s a sharp angle.

When you create G1 (tangent) continuity, it means that the surfaces have equal angles in their tangency.

When you create G2 (curvature) continuity, there’s not only equal tangency, but also equal radius in the curvature on both surfaces. These are the surfaces that don’t show any flaws when lights are reflected on them. That’s why Zebra analysis is so important in these cases. When the stripes in the Zebra analysis are continuous, then you have good continuity. 

You will also notice that when you click on the loft, you’ll get a couple of new icons. If continuity among surfaces is involved, then you will get at least three of them.

The one depicted below (the one to the right) will define the continuity. This is the one that will only appear if at least one surface edge is selected as start or end profile. Please remember that you can change this setting at any time.

The following icon provides different options for the loft operation.

 You can decide between a smooth fit and ruled loft (the latter will have G0 continuity between all internal profiles). 

You can also define if the loft is normal to any of its sections.

Draft Angle can also be triggered from here, although we’ll see that the last control is basically a Direct Manipulation element for Draft Angle.

The last option is to close the surface or solid, which can also make a periodic surface (more on this later).

The control for Draft Angle can also be accessed via Direct Manipulation. Once you click on the triangle, you will get a handle that will control the magnitude of the draft angle, and reach very interesting results.

 

Surface Modeling in AutoCAD - my AU 2010 class - Part 2

Let’s continue with the exercise we started last post, and work on the modeling.

The first surface we’ll do is the Network Surface. You need to select two sets of curves, which have different directions. Once you finish selecting the first set of surfaces, you’ll click enter (or whichever method you have for this), and then the second set of surfaces.

Let’s take a look at the Ribbon. The option for Surface Associativity is on. This means that if you change the position of the elements that originated the surface, the Network Surface will also change. The control lies within the original curves. This is a great differentiator with strict NURBS modelers, which create a NURBS surface once you click OK. Please note that you can also do this, by selecting NURBS Creation. In this case, all associativity is lost.

Let’s create our first surface using the Network command on the Create panel in the Surface tab. Remember to select the first set of curves in one direction, and then the other set of curves, after clicking Enter.

If you have Properties open (if not, you can get it in many ways, but a simple one is through the Quick Access Toolbar), you will notice that if you select the surface, it is not only a Surface, but it’s called a Network Surface. AutoCAD’s surfaces (if not created with the NURBS Creation option) are explicit surfaces. It means that at any time, they keep the properties of the method they were created with. We’ll see more value to this when we check the loft and the patch.

So we have the base of the case, but we now need the sides. We’ll use the Loft command. LOFT has been around since 2007, but it has been enhanced, so let’s check some of these enhancements. In our example, we are going to use a curve and a surface’s edge. In the past, loft was only possible with open or closed curves, and they had to be planar, at least the initial and final profile.

Starting in 2011, we can loft non planar profiles, and when one of the profiles is a surface’s edge, we can control the continuity.

Let's wait for next post to learn all about LOFT and continuity. Next time, I'll post from Mexico City, while doing the training for the channel, on both AutoCAD and Suites.

 

Surface Modeling in AutoCAD - my AU 2010 class - Part 1

Submittal for AU 2011 is reaching its deadline, and of course I have not sumbitted yet. However, I do have a plan around what I'll propose, so I know what I won't be talking about. This is why I wanted to share the document from a quite successful class I did on the AutoCAD 3D Power Track last year.

I'll post it in chapters. After finishing these posts, I'll add some more around enhancements on surface modeling in AutoCAD 2012.

So here goes part 1:

 

AutoCAD 2011 introduced Surface Modeling, bringing unprecedented power and flexibility into AutoCAD. Between meshes, solids and surfaces, you can have different approaches to modeling. And what is even better, there are workflows between them.

 

There are some aspects to keep in mind when talking about surface modeling in AutoCAD. We need to talk about the many object types, but the main guiding principles when we built the feature were: explicit surfaces, associative surfaces, and direct manipulation. Any surface created with the option NURBS Creation on, or converted into a NURBS surface will be defined only by the grid of UVs.

 a. Explicit Surfaces

However, you may prefer to work with Explicit surfaces when the method of creation is clear, and there is no need to change it (Revolve, Extrude, Loft, Blend, Patch). These surfaces maintain the relationship with the method used for their creation. For example, a revolved surface will let you change the angle of revolution any time after its creation. If it was a NURBS surface, this would not be possible that easily.

 b. Surface Associativity

But we also have Associative surfaces. An Explicit surface could have been done without the Surface Associativity option. In that case, a change in the geometry that originated the surface will not change the surface. An associative surface is controlled by the original geometry. This means that if you used two splines to generate a loft, the control for the edges of the loft will not belong to the surface, but to the splines used for its creation.

Summarizing, a surface can be both Associative and Explicit at the same time. It can also be Explicit only. A NURBS surface can’t be associative.

c. Direct Manipulation

Most of the interactions with surfaces and splines are done through the canvas, and not involving dialog boxes, which tend to disrupt the process. You can see direct manipulation in the multi-function grips on splines, on selection cycling, and in the controls for surfaces. All these will be covered in the following example.

 d. Example of surface modeling

Even more important than learning the commands and different surface objects, is to know when to apply which surface. Let me explain the whole process by showing you the final result and identify the surface types.

 

The first surface we’ll do is a Network Surface using the three longitudinal curves and the two curves we did between them. A Network Surface needs curves on both directions, and they don’t even need to be intersecting. Of course, if they intersect and have coincident vertices, then the surface will look exactly like we want. If not, there will be some interpolation done by the computer, which we won’t exactly control.

 

Now we’ll complete the sides. We will use a Loft for this purpose, and we’ll consume the remaining spline, and the edge of the surface we just created. Why? Because the selection of a surface edge will allow us to control the continuity between the surfaces. In this case, we want a perfect curvature between these two surfaces, so we’ll need G2 continuity. If we had selected both splines for the loft, we would not have had the chance to define continuity. That’s also the reason why we needed the Network Surface first.

The next operation is a loft, but in this case we can use the splines (the top spline and the top splines from the sides). Why? The answer is simple. We just need to have coincident edges, but not continuity, since this top surface will be a second part of the cover. We can also use the surface edge with G0 continuity. If we do this, we’ll have associativity between the surfaces.

 

The last operation will consist in closing the gaps on both ends. This will be done with Patch Surface. Patch can operate with surface edges or curves, but in this case we’ll use surface edges, even though we’ll force the solution to be a G0 (with no continuity in curvature or tangency).

 

In part 2, we'll go through each section in more detail.

Viewport controls in AutoCAD 2012

There have always been great stories of interoperability around AutoCAD and 3ds Max. I remember starting to work on 3D in AutoCAD in order to get renders in Max back in the AutoCAD 12 – 3D Studio R2 for DOS. After exporting 3ds from AutoCAD, trying to figure out how many normals were flipped and then applying materials and lights, you got pretty good results. Of course, any change in AutoCAD would mean redoing the whole process again, at least for the edited pieces.

We’ve gone a long way since then. In the future I’ll talk a bit about the File Link Manager in 3ds Max Design, which for some reason does not get that much attention from some users.

But today I wanted to talk about a somehow minor feature in AutoCAD that will help a lot in creating more consistency across applications. Especially in the new context of the Suites, when we ship AutoCAD and 3ds Max together in Autodesk Design Suites Premium and Ultimate, we want users to feel in a familiar environment. You always have an application where you spend most of the time. If this application is AutoCAD and you use 3ds Max Design every once in a while, then any help to make the interfaces more familiar is a good thing.

The viewport controls for AutoCAD are new in AutoCAD 2012, and are a great time saver if you work in 3D and change visual styles and views very frequently. Having been using these controls from the early prototypes, every time I had to go back to AutoCAD 2011, it felt really bad not to have these guys on the top left of your viewport. This is how I normally realize how useful a feature is. Just go back one release, and feel how the number of clicks to do something grows.

So what can you do with these controls? Basically they allow you to change the configuration of viewports, the views within them and the visual styles.

Check out how easy it is now. No need to go to the View tab in the Ribbon. Or you don’t use Ribbon? Then you can turn off your View toolbar, and get some more real estate.

Now in 3ds Max Design, you got the same control. Slightly different options, but we’re talking about two apps with different targets anyway. The good thing is that there is no doubt that in both cases, you are going to the same place in order to look for visual styles. And yes, it’s been like this in Max for a long time, so now, for all of you people using both AutoCAD and 3ds Max Design, you get to exercise some muscle memory and definitely work a little faster.

As you can see, same is happening with the Views. AutoCAD displays the available views, same as 3ds Max Design. Max does offer more options like Lights and Cameras. Now, if you add a camera in AutoCAD, you’ll see an extra option for displaying cameras in this same control.

 The first option lets you switch from a single viewport into a multiple viewport configuration. This was quite difficult in AutoCAD before, and now it’s just a double click away. You can also access ViewCube, NavBar and Steering Wheel options from this same place. Guess what.  Same in Max.

If you go back and forth from single to multiple viewports, you'll see that your visual styles are maintained. 

By the way, I want to share a small tip. When you click on this control, stay on top of it until you get the drop down menu. If you click and move the mouse, you won’t get anything. Is this a bug? Well… not really. This is a way to avoid people clicking close to the control by accident and displaying the drop down when they don’t need it. In these occasions, the user will be probably moving the mouse around, so there are no chances of getting the menu by accident.

In a nutshell, a small improvement that saves big time, and provides more consistency when working between AutoCAD and 3ds Max Design. Now that they are shipped together in many of the new Suites in the Premium and Ultimate flavors, it is even more critical to decrease learning curve and share as many components as possible.

In the future we’ll also talk about the Autodesk Materials and File Link Manager.

 

Periodic Splines in AutoCAD 2012

You may remember that I did some posts around splines for AutoCAD 2011. If you believed that a lot of progress was made, you are right. However, there were a couple of aspects we wanted to enhance. The most important one was to get periodic splines in AutoCAD.

So what does this mean to you?  Let’s say you created a spline in AutoCAD 2011 (or previous), and came up with something symmetric. I just created one in AutoCAD 2012 using the corners of this square. Note that I can close with right click menu, and not have to define end tangency.

If I select the spline and show its properties, I can see 4 control vertices.

In the past, you would have seen 5 control vertices. Nothing shocking until you wanted to rebuild the spline. At that point, the shape would become asymmetrical, with a concentration of CVs (control vertices) around the place where you closed the spline.

As you can see, in AutoCAD 2012, even after rebuilding the spline, we get the right shape and the right amount of control vertices (in the right place).

This will also directly impact (in a good way) any shape you create based on these periodic splines. I just copied the spline along the Z axis, and scaled one of them, so as to get a nice loft. By the way, have you noticed that the loft is giving a real time preview as you select cross sections? This is just another enhancement in AutoCAD 2012.

After getting the loft, I just made another exercise.  By converting the loft into a NURBS surface, and showing the CVs, you can see the same symmetry from the splines.

 

AutoCAD 2011 hits the surface!

At last! Now I can start showing all the stuff we've been developing for the whole year.

AutoCAD 2011 is out! 

Since you're reading What a Mesh!, I assume you have a strong interest in design and modeling.

So let's focus on those features. I will be posting videos, tutorials, white papers and tips & tricks on the following months.

Ever needed to model surfaces in AutoCAD? We did have the ability to extrude, loft and sweep open profiles and get them, but now we have a full feature around Surface Modeling. But not just a NURBS modeler.

We are introducing Explicit Surfaces, which means that the surfaces will have the properties according to the method of creation at all time.

What about moving a curve that was used for surface creation? Well... let me introduce you to the concept of Associative Surfaces! Surfaces keep associativity with the curves and surface edges used to create them, even after a trimming operation. Nice!

So you want more? More control perhaps? We can use parameters on the surfaces, and drive them through the Parameters Manager introduced in 2010!

Not everything is about surfaces. We also enhanced solids and meshes.

If you liked the concept of Direct Manipulation introduced with Mesh modeling, I challenge you to find one task dialog. Not one for creation and editing of surfaces (just one for rebuilding NURBS). This means, you work faster. All can be done in canvas.

What else? Better splines. Much better splines, really. Stay tuned.

But that's not all. We added better interaction for complex models. Selection Cycling and Object Culling will help you select the right entities, and not display undesired grips.

Have you heard about point clouds? Do you imagine 2 billion points (yes, 2,000,000,000) being attached into AutoCAD without performance loss? Not science fiction. You got it.

Now you can also have a much better representation of materials in the viewport and rendering. And all the materials are shared with Revit, Max and Inventor. 

Talking about interoperability. You may want to understand how to operate with Inventor, Revit and Max. We'll also cover these aspects.

So stay tuned for the next posts.

Until then, here is an interactive overview of AutoCAD 2011.

Interactive Overview of AutoCAD 2011