Full width home advertisement

Post Page Advertisement [Top]




In the 2D design world, you have a thin line between creating and modifying images or vector graphics. However, when it comes to 3D Modeling, most CAD design applications have many and often confusing different modes and often commonly even different interfaces for each method.
Your focal point In 2d design is the visual output, and so as long as it looks good, it does not matter how you created and modified your design. However, this is not the case with 
3d design. One of the most critical aspects of 3D designing is understanding a good topology structure, and it all starts with how you create and modify your geometry.
Nowadays, most professional industries use 3D modeling in one way or another. Regardless of the design is for manufacturing, 3D printing, Gaming, or advertising, you can run into non-manifold, difficult objects to render, and high poly models, unless you focus on the topology structure and that all starts from the way you create your objects. 
SelfCAD has dramatically improved the 3D modeling flow, they have managed to unify all aspects of 3d design, under a single user-friendly and intuitive interface, without compromising any functionality. SelfCAD is one of the few software that provides such a wide range of technical and artistic tools. 
SelfCAD tools emphasize good topology. Still, the more advanced tools and features you use, the more you can create problematic geometry unless you understand what each function is supposed to do and the best practice for using them. 
SelfCAD also has several Geometry fixing tools, but they all create an entirely new mesh, and so you lose control of the topology design. These fixing tools are great to use on a final object, but while modeling, it’s best to have beautiful low-poly objects that you can easily modify while still keeping its basic underlying structure. 

About this article 

Most of what we educate in this article are universal concepts and best practices. We can quickly teach how to use the SelfCAD tools to design 3d objects, but the purpose of this post is to prepare for professional 3D Modeling, in a way that will land you a job in the future, regardless of what design software you use.
The focus of this article is to cover all options for creating 3D objects. We may briefly explain some related features. We will still stay focused and instead release new blog posts to cover all other 3D modeling topics. 
We also invite you to join the SelfCAD university channel to learn about new blog releases, and we ask that you feel free to post any questions, we will be happy to answer them, but more importantly, this will help us see what’s missing. Your comments and suggestions will help us improve and teach the same for other students.
Before we look at the 8 ways of creating 3D models in a 3D modeling software, we would like to check on a few key considerations in 3D modeling.
Geometric primitives vs. imported objects 
Photoshop designers will often reuse parts from other images, and most 3D designers will, in a similar way, reuse whole or components from other 3D objects. SelfCAD supports many different import and export file formats, and you can even browse and import from a 100,000+ MyMiniFactory library of 3D printable objects, directly from within the SelfCAD editor. You can modify any imported mesh using a wide range of editing tools. 

However, Geometric primitives are not like your typical imported 3D object. Geometric primitives are parametric, which means they are using mathematical functions that you can customize. Moreover, because the 3D Modeling software understands what shape you are working on, it can generate well optimized and good quality topology. 3d designers prefer to use Geometric primitives as a way of creating good quality and low-poly 3d objects.

Linear vs. circular based Geometric Primitives 
Not all Geometric Primitives are equal. Cubes and other planar shapes have plane related settings. That includes customizing the size of the primitive and the number of segments for each polygon. You can update the volume of the primitive after it was finalized, by using 3D transformations. You can also increase or decrease the poly count with SelfCADs resolution and other editing tools, so the settings are not crucial. 
On the other hand, circular shapes create the 3d object based on circular revolutions, and the number of segments directly correlates with how many revolutions it makes. The resolution tool will only increase or decrease the number of faces on each polygon of the shape, but changing the segment count in the primitive generator will directly affect the number of polygons and, consequently, the actual design of the 3d object.
You can increase or decrease the smoothness of any polygonal object using the Round object and the Simplify editing tools. Still, the circular shape generators are the best for managing the smoothness of basic primitive.  
Circular shape generators use a radius for size. In contrast, planar objects and transformations use a bounding-box based measurement, and that is half the size, just so you know and do not get confused when for example you create a sphere with a radius of 50, and you see it as a size of 100, this is not a problem, it’s just using a different measurement system. 

In the above example, you can see that a cube always looks like a cube; regardless of the number of quads, you can also see on the second row that we can set different segments for each side. 
In the 3rd row, you can see that a cylinder can become different shapes based on its vertical segments. In the last row, you can see how changing the arc settings allows you to create forms that are not completing a full closed circular shape. 
You can also see on the two bottom right objects that circular functions allow you to set different top and bottom radios; hence the head is smaller than the bottom. You can see that adding horizontal segments does not affect the shape, much like in the cube example, as the horizontal direction is no longer a circular shape. 
In the above example, you can see that because a sphere is circular in all directions, modifying horizontal segments will also result in a different shape.

The same concept applies to all geometric primitive shapes. Circular shapes use a circular mathematical function to create the topology of the object, so changes in the settings will affect the primitive design. In contrast, planar objects use plans, and so segments are just used to divide the objects into parts that you can use to modify the shape.

Triangles vs. quads 
Triangles are always planar, you can only create a triangle if all three vertices are on the same plane, but you can create a twisted rectangle, so complex shapes, such as a torus knot will use triangles. Otherwise, it may result in non-manifold geometry. 
A Cube and a Torus use quads, a cylinder, and a sphere will use quads for all surrounding faces and use triangles for its circular top and bottom because triangles are much better for representing circles. All the other primitive shapes use triangles. 
The variety of quads vs. triangles is helpful because they all offer different topology structures, and designers can choose what works best for any particular design. 

Why does it matter what style, and how many faces you have? 
The main goal of using primitives is to extend and deform them, and for that, you need to select and work directly with the topology structure. 
In the above example, you see how bending a simple cube without additional faces result in skewing, while the subdivided cube has enough segments to bend. They bend so beautifully because the quad face structure works very well for deforming objects.
You can also see a 270-degree angle cylinder being extruded and extended into a rounded staircase. This particular use case benefits significantly from the triangular structure on top of the cylinder. 
SelfCAD has the industry's most diverse editing and deformation tools, and we will discuss them all in a separate article. For now, let’s stick to how to create 3d objects in SelfCAD. 

Custom shape generators

SelfCAD also included specific shapes like gears and Screws, etc. The most exciting of all the custom shapes is the Shape Generator. 
The Shape generator works similarly to the other circular shapes, but it enables adding many forms on top of each other effortlessly. You can have different settings for each layer, and SelfCAD will automatically make a smooth connection between the different shapes. 

How to bridge between 3D objects 

The shape generator is unique to SelfCAD and is best for creating layered-based objects when all layers are on top of each other. Still, when you need the flexibility to connect in many different directions, then loft is a better choice. 

In the above example, you have two cubes at the bottom, and two cylinders on the top and the loft tool connected them vertically using two different settings.
On the left, we used a simple connection. You can see how the connecting shape starts rectangular at the bottom, and it finishes circular at the top, where it connects to the cylinder. On the right side, you can see we joined the same shapes, but we added a twist to the connection. 
Similarly, we made two horizontal connections. The top is a direct connection without any special effects, while the bottom added a negative bevel effect. 
Automatically making such smooth transitions between geometric primitives and allowing them to use it in all directions is a compelling feature and a big time saver compared to manually designing such shapes. 
The Loft is a standard tool in other CAD software, primarily for creating organic shapes using profiles. Some CAD software has different means to bridge between objects that do the same we did with loft. However, one of the ways SelfCAD has simplified the design is by consolidating and making a single interface, and making the same tools work across all object types; this reduces the aggregate amount of tools, and significantly shortens the learning curve. We will soon demonstrate how to use the Loft tool for profiles. 

Creating 3D geometries using 2D Drawing

Regardless if you are an artist or mechanical designer. Drawing is an integral part of any professional 2d and 3d design flow. SelfCAD has a diverse range of artistic and technical drawing tools. However, before going into any software and feature specifics, let’s first get familiar with how a 2D drawing becomes a 3d object. We will also showcase some design challenges to make it easier to understand and appreciate any specific tool or feature and to help you make the best out of them. 

The above image demonstrates the most basic drawing flow. You start sketching a 2D contour on a 2D plane. You then fill the profile to convert it into a 2D surface. At last, you add height, and it becomes a 3D geometry. We sketched the shape on the bottom plan; we just rotated the camera to look at the scene from atop, birds-eye view, so we can better draw and show it from this angle. 

Extrusion vs add Thickness. 

Once you already have a 3d mesh, you use extrusion to extend faces, and you use the Add Thickness tool, to make hollow objects. We will discuss and explain them in the editing blogs. Related to working with surfaces that have no volume, both options should technically be doing the same, so SelfCAD made them work in two different ways as follows;  
Extruding a surface creates the sidewalls and leaves the bottom open, while Add Thickness creates closed shapes from all sides.
The concept of extrusion, in general, is to move up the selected surface and build side connections. Some CAD applications have settings to switch between adding a bottom face or leave it open. SelfCAD, by default, closes all surfaces, as that’s the primary use case. You can always delete any surface, so there is no need to complicate and add such settings, but in the case of surfaces, SelfCAD will leave them open, since the Add thickness is already making closed shapes. 
Add thickness is the preferred option to convert a surface into a volume while extrusion is best when you like to keep it open and perhaps later use the add thickness tool to add the wall depth.

In the above example, you see the surface on the left. The second from the left used Add Thickness to create a solid object. The 3rd used extrusion, and added additional plans but did not close the shape. The last form added thickness to the previous to make it a watertight, hollow object. You can also use Fill Polygon again, and it will close the shape. Fill polygon converts profiles into surfaces and also closed holes in 3D meshes. That’s the beauty of SelfCAD’s reusable tools.    

What is a planar design 

When analyzing the above design, you can see that the 2D sketch is planar only when looking at it from top to bottom; you can describe all details on a single top-bottom plane. The full height is linear, without adding any additional design details. That’s not the case when looking at it from a side view. You can’t draw all design details on the front-back or left-right plans; this is why you have many drawing planes.  Some designers, however, prefer using a single plane and rotate the drawing or final object. It’s a matter of choice. The key is that a 2D sketch flow only works for a planar design whereby the last axis is always linear. 


3D Sketches
The Fill Polygon tool used a 2d constrained triangulation. Still, it can triangulate 3D sketches because the Fill Polygon tool also includes a 3D pathfinder, that finds all 2D surfaces in a 3D profile. We will soon illustrate and explain its use and best practices. We will also start explaining different options for how to sketch 2D and 3D Profiles. We will also demonstrate other options for converting a profile. For now, let’s first continue exploring what you can do with a 2D profile using the triangulation approach. 

Solid vs. Hollow objects

The above design consists of a single polygon and path. The surface covers the entire inclosed area of the profile, and the 3D mesh is Solid without any cavities. However, you can also triangulate profiles with holes and with multiple paths. 

In the above image, you can see it's also a planar shape; the height is linear, but it’s different from the previous model, in the sense that it has many different paths. Each partition has its closed polygonal chain, describing its wall thickness. You can also see that certain parts of the wall have different heights than others. 
You can technically make such a design using geometric primitives and box modeling techniques, box modeling is a common approach for interior design. Still, designers often use drawings, especially when making shapes with rounded surfaces.
In this example, we did the same three steps as within our first example. We created a profile on the front-back plane, we filled the sketch, and we added thickness to the surface. So far, all the same steps as in the first example, except for changing the drawing plan. We draw this on the front-back plane.
We then selected (marked in Yellow) all the parts that we like to extend further, and we extruded them to make the final shape. We then added texture for visualization purposes. 

The order of extrusion
The order of extrusion matters. If you switch the last two steps, you will get a non-manifold mesh. We elaborate on this in the editing blog. 
Cutting holes in objects
In the first example, we had a single solid path profile, that we converted into a solid object of the same height. In the second example, we had many paths, and we used different levels of extrusion. Still, both objects had no holes.  

The above picture frame example includes an intricate pattern that is not easy to draw. We used the SelfCAD freehand drawing pattern option to make this design. Nevertheless, you can see the wall thickness is the only part with any volume. You have a hole in the center, and you have close to 100 holes within the surrounding walls. 
This entire design took less than a minute to design because the freehand drawing automates the whole process, but you can do the same using the 3D Sketch tools, it will just require making a few additional steps. We will elaborate on this soon. 

Understanding the drawing Topology structure 

We’ve already explored almost all planar drawing and triangulation use cases. Still, without understanding the topology structure, it would be difficult to make sense of them all. It will undoubtedly be challenging to make the best out of the different available drawing tools.  

Constrained Delaunay triangulation
The most common triangulation algorithm uses a 2D Constrained Delaunay triangulation method, which is what SelfCAD is using in many parts of the application, including freehand drawing and the fill polygon tool. Delaunay triangulation can triangulate convex as well as concave polygons. For the topic at hand, we only need to understand the “Constrained” part and why it’s so helpful for design and its drawbacks. 

What is a Constrained triangulation?
The term constrained means that the algorithm keeps the same vertex count and will not add, remove, or reposition vertices; this means that the original number and position of the vertices directly influence how the algorithm will create the final mesh.   

How Constrained triangulation helps for design 
There are two huge benefits of using a Constrained triangulation. The most significant advantage of keeping the same vertex position and count is that you can make shapes within shapes. A drawing within another polygon does not make any sense as a final design, but it’s an integral part of making a multiplex design. The second benefit is that you can merge adjacent planes that are part of the same 3D profile. You just need to remove the duplicate vertices, and you get a watertight mesh. Sounds confusing? Let us make an illustration and clarify them all. 

In the above example, you see a complex 3D profile with a circle on the bottom, within that circle, you have a custom drawing on the same plane. You also have a cylindrical surface as the height. Finally, you have a circular top with Criss Crossing lines inside. 
On the right-hand side, you see the mesh we created using the Fill polygon tool. So far, you see no significant difference from all added parts to the design. It just created slices in the mash that matches the profile cuts. If you use the resolution tool with a “0” settings, it will remove all these extra details because these details add no value to a simple cylinder that you see. So, what’s the point? Well let’s illustrate the next steps,

The second object, In the above example, is duplicated from the first object. We just rotated the copy to show both sides. You can see how we can select parts from the mesh corresponding to the profile parts we use to create and triangulate this object. 
We used SelfCAD’s Inset tool to make the distances between the four parts, and we then added texture for visualization purposes. You can also use negative extrusion to create a placeholder for adding Glass or other materials. We then extended the bottom part, using extrusion, and added a different texture.  We elaborate more on these techniques in modeling and editing articles. 
We then added a circular molding around the Tabletop using SelfCAD’s Follow Path tool, and we placed the rounded text in the center, using SelfCAD’s Stitch and Scoop tools. Let’s explain them both. 

How to use Follow Path with profiles 

Follow Path, like most tools in SelfCAD, is a reusable tool. It has two main functions when using it for a mesh. One mode extrudes shapes along a path, like the popular, Follow Me Tool In Sketchup, and the other is for making copies in the direction of a sketch, similar to the array command in AutoCAD. When it comes to profiles, you are limited to the extrusion option. You are not limited to a single path. However, you have to use it wisely to get good quality meshes.  

In the above example, on the left, we used a sophisticated profile, and it created a single mesh of excellent quality. The 2nd example used an individual pattern whereby the inner lines intersect the outer circle. And we got many separate meshes and brakes between each. In the 3rd example, we separated the path into two parts, to avoid the intersection and the Follow path created to beautiful meshes, at last, we merged them using SelfCAD’s Stitch and Scoop Union tool.  

The FollowPath flow

The small red shape is what we used to trace the profile edges. You can use any drawing of your choice. The flow is quite simple. You first select the profile that should follow; in this case, it’s the red circle. You then choose all other paths and click the FollowPath tool. 

Duplicated vertices and faces

In the first example, we got a single mesh covering the entire Sketch. In the second example, we also got a single mesh for the circular part, but we got a separate mesh for each line since the lines did not make up a closed path. 
We tried to unite them, using the union boolean tool, we got a non-manifold error because all the intersecting line meshes had too many overlapping vertices in the center. Hence, we first merged all inner edge meshes, using SelfCAD’s merge tool. We then used SelfCAD’s remove duplicates tool to remove all overlapping vertices. Finally, we successfully applied the union tool to join the inner and outer segments. Boolean works very well on intersections, but often fails at overlapping faces and vertices. 

Boolean operations 

Before moving forward, it’s essential to understand the four operations you can do with interacting shapes. 
  1. Union. You keep both objects, and the function combines them into a single shape, it’s different from merging since it rebuilds and stitches together the topology pieces. 
  2. Difference. You keep only one and cut out the part of the shape that intersected. It’s important to note that the Difference function multiplies based on the number of objects. You have two possibilities for two geometries because you can remove object A and keep object B, or remove object B and keep object A. The more objects you add, the more possibilities you get. 
  3. Intersection. You keep both shapes, except for the intersection part. 
  4. Exclusion. You remove both shapes, except for the intersection part. 

Boolean is the scientific name describing the above four functions. Some software reuses the same name for these tools, and some have a custom, more intuitive naming convention. SelfCAD calls Boolean operators “stitch & Scoop” and names each of the four settings within the tool with the common names, as they seem intuitive enough. 

The above image illustrates the available boolean operations for two intersecting objects. Most 3d modeling applications tend to reserve stitch and scoop for intersecting volumes and offer Trim and Brake commands for profiles and surface cutting. 
Boolean operators are infamous for creating inadequate topology structures. They overtake and programmatically rebuild the entire mesh. They are prone to errors when using it for non-manifold objects, like those with many overlapping faces or vertices.  
SelfCAD was built from the ground up. They developed Most algorithms and features by themselves. Still, like everyone else, it’s not a good idea to reinvent the wheel, so they sometimes use widespread and proven open-source algorithms. 
In Boolean tools, they used the same libraries that most CAD software use, Including Blender, etc. Despite being an online 3D Modeling software, SelfCAD used WebAssembly to cross-compile the C++ library and work for the browser. So the same issues apply to all software. You only need to have a basic understanding of what they can and can’t do. We hope to elaborate on more Tips and Tricks for boolean in the Geometry fixing blogs. 
When it comes to 2D sketches, you get much more flexibility and magnificent topology structures using the trim and brake commands. Hence that became the standard. SelfCAD has just simplified these, as we describe below. 

Trim vs. Boolean 

Trim and Boolean operators have one thing in common. They both use intersection as a way of cutting parts from objects. However, the underlying logic is entirely different. 
3D Boolean tools cut one volume from another; this means you need to have a minimum of two shapes; it also means you need to have a Manifold mesh. Boolean is also limited to four predefined options. Most importantly, the need to have intersecting volumes.  
Trimming, on the other hand, is not limited to having a volume, you can even trim open paths, and you can cut parts from a single profile. You can also trim intersections of tangent lines.
The above example illustrates a few trimming options when you have a simple square with two diagonal lines. The second image is a bit more complicated. We draw a rectangle, and the connecting arc on top (not in any particular order), we then draw a spline from the bottom left vertex to the center point of the sketch, to the bottom right corner. We then deleted the two horizontal lines. This step had to be the last since we were looking to intersect the entire sketch’s center point.

How to find the center of a drawing 

The drawing flow matters. In the above example, we did not calculate the center point manually. SelfCAD automatically shows all center points, so after drawing the first two parts, we got the updated center point that we used to draw the spline. Similarly, SelfCAD automatically adds an intersection point to the center of each line, arc, etc.  making it much easier to connect other shapes for trimming operations. 

How Sketch Trimming command works

In most CAD Software, you have a separate Trim function. The flow involves activating the trim tool, and while it’s active, you select the topology parts that you want to remove. In SelfCAD, however, this is greatly simplified. SelfCAD automatically splits intersecting edges so you can simply choose any segment you want to remove and delete them. 
In the above video example, you see how easy it is to trim in SelfCAD. It’s just important to note that SelfCAD will only add the additional vertices when you either draw them as a single profile or when you later merge them as the designer did in this video. 

How the brake intersecting edges 
Like trim, the braking command adds a vertex at intersections, but unlike trim, it will keep all lines. Once you break them, you can triangulate the sketch and get an excellent topology that you can modify later as needed. 
SelfCAD automatically breaks all intersections within a single profile, so there’s no need to have either of these tools, and SelfCAD selection adds even more flexibility; we elaborate on this, in the selection blogs. 

Introduction to Freehand Drawing

SelfCAD’s freehand drawing is exceptional in that it implemented a live boolean tool. No other CAD software has such an interactive 2D drawing boolean tool. The freehand drawing also offers a unique freehand drawing brush, that enables setting the brush thickness and style. 
In the above picture frame example, we created the entire drawing in just two drawing steps. We selected the freehand brush with the default round style option and with a thickness of 40, and we draw the rectangle. 
We then switched to erase mode. Change the brush thickness to 20, select a pattern, and draw the same path. We then clicked the confirmation icon and got an incredible shape. We also used the snap to grid option in the precision setting for smooth and precise drawing. 
In traditional CAD drawing, you would need to add an offset thickness manually and round the corners for the first rectangle. At the same time, the inner pattern design would be tough to accomplish. 
In the above video example, you can see how the designer first created three circles and later started adding the connecting pieces using the brush tool. It automatically made union connections. You can see that once the designer added more parts and created a closed hole, SelfCAD automatically marked them in red as a sign that this needs to be subtracted and kept as a hole. 
This automatic hole detection works in cases where you draw closed shapes and do not draw in an already created form. In other words, when you are not subtracting, instead just creating the outer perimeter and you expect the software to recognize your intentions. However, when you plan to subtract directly from another shape area, you need to switch to the erase mode.  
You can also see how the designer is cutting parts from the seat and is making holes in the wheels. The designer had switched to the erase mode because they required cutting sections from a previously created shape. You see how the object has finalized after clicking the configuration button and creating a mesh, as it finishes the drawing. 

How to convert a freehand drawing into a 3D mesh

The freehand drawing aims to create 3D objects quickly, and so clicking on the confirmation icon will complete the sketch by converting the design into a mesh with a height of 20. You can change the height to the correct value or keep the default settings and later scale the object. As long as you have some height value, it will create a mesh on finalization. If, however, you set the value to “0” it will finalize as a profile as within the 3D sketch that we will discuss soon.  

Interactive vs. isolated tools 

SelfCAD has two types of tools. Tools like 3D Geometric primitives generators and the freehand drawing are isolated, meaning you need to finalize and exit the feature before using other parts from the SelfCAD editor. In contrast, other tools like 3D transformation, deformations, and 3D sketch, are interactive in the sense that you can use different features, while still keeping the first tool open and active. 
A general rule is that a tool, which is required to create or significantly modify the geometry structure, will be isolated because you can’t change the mesh before finalizing it. Whereby tools that need less geometry processing will use an interactive tool approach. 
In the case of freehand drawing, you are working with a sketch before finalizing it into a mesh. However, interactive boolean operations are not smooth; that’s why you don’t find them in other CAD software. SelfCAD was able to accomplish the fantastic feature. Still, only while keeping this tool isolated and, therefore, because you can’t use the general application editing tools, you will find a “Move points” as the third option in the drawing. Switching to move points will allow you to edit the sketch. 

Moving a 3d sketch to freehand drawing 

While in the freehand drawing, you can drag and drop any object with less than 100K faces into the scene, and SelfCAD will flatten and convert it into a sketch. You can drag-and-drop meshes, profiles, and surfaces alike.  
You can also double-click on the mesh, profile, or surface image in the scene graph, while the freehand drawing is active, and it will convert. This option is best when you need to keep the original object in place, and it’s difficult to position correctly using the drag and drop method. 
The drag-and-drop works in drawing as well as in erase modes. It behaves according to the current method. Some people drag-and-drop 3d primitives to test simple drawing. It’s sometimes more accessible to drag-and-drop, vs. actual sketching.  

3D Sketch 

The 3D sketch is similar to what you have in most professional 3D CAD software. The following are the main differences between the 3D Sketch and Freehand drawing:
  • The fact that it creates a profile instead of a mesh 
  • 3D Sketch is an interactive tool
  • You can draw 3D sketches 
  • You can Sketch almost on anything, including between objects and other drawings, as well as directly on objects  

What is a profile? 

A profile, also known as a sketch, does not have faces and thus is not a mesh. The term sketch refers to the art of sketching while the name profile originates from what artists often relate to an object's profile, like a person’s profile. A profile can have any drawing primitive, like lines, arcs, and splines, etc. A profile can be 2D or 3D. 

What can I do with a sketch? 

Some professional designers may create profiles as helper objects; similarly, you would use measurement guides as a reference for how to create or modify other 3D objects. Still, the primary use case for a profile is sketching objects that you later convert into a 3D mesh.

How to offset and edit a sketch 

We mentioned above that you could freely use all standard mesh tools for profiles and surfaces alike; that gives you many options for modifying and extending meshes without duplicating and adding a different interface for working with sketches. 

The above is an example of just a few commonly used features. You can also use Extrusion, simplify, resolution, etc. One of the unique tools that engineers use a lot is the Add Details tool. The Add Details is handy for creating interior designs, etc. For a more detailed overview of how to work with profiles, see the Working-With-Profiles overview. The add details tool was recently updated and added an offset option, which adds even more flexibility.  

How to convert a sketch into a mesh 

SelfCAD has four ways of converting a profile into a polygon mesh. Not all options are equal, and between them, you get a lot of flexibility that can accommodate all 3d design use cases. 

  1. Fill polygon 
  2. Loft 
  3. Revolve 
  4. Follow Path 


What is fill polygon, and how to use it? 

Fill polygon triangulates polygons. It works on meshes (in a case when the geometry is missing some faces), and it works on profiles to convert the sketch into a surface. Like most other features in SelfCAD, Fill Polygon is a reusable tool that you can use in many contexts. That means it works on a mesh, profile, and a region selection. 
A region selection refers to the act of selecting sub-elements from a mesh. We elaborate on this topic in the 3D modeling and editing article. For now, it’s just important to know the concept that you can manually select parts from an object. In the context of this article, we are talking about choosing single polygons from a mesh or profile that you like to triangulate, instead of having the software search and find what it thinks you want to fill. 

How to use a 2D triangulation for creating a 3D mesh?
Every polygon mesh consists of 2D polygons, but to find the 2d polygons, you first need a 3D pathfinding algorithm that can find the best 2D polygons from the 3D path provided. The more complex the shape gets, the more difficult it becomes to find the correct polygons. Therefore it's always better to triangulate first one surface and later use the extrude tool or the add thickness tool to complete the other sides to complete the polygon mesh. 
We already illustrated above how we first fill a surface and later add thickness, but that only works for planar shapes, as described above. The added benefit of 3D sketching is that you can create intricate and organic forms. 
Well, this is why SelfCAD added a 3D pathfinder. Some CAD software forces you to manually select and triangulate each polygon separately, while SelfCAD tries to find all polygons so that you can fill the entire shape at once. 
Still, to make it work, you need to have a basic understanding of the polygon structure, and you need to keep in mind that it’s still a 2D triangulation after all. Can you show me an example? 

The above example is the same as what we already illustrated above. Now let's examine the flow. We first draw a circle. We then used two inner circles as a guide to position the arcs; we then draw four arcs that make the internal shape.  
We wanted to add height, but the fill polygon algorithm needs all circular details, so instead of manually drawing all the vertical lines, we simply extruded the circle. We did not want to include the inner drawing, so we selected just the outside part and extruded. We then drew the additional lines, and as illustrated above, it gave incredible results. 
The most crucial part that caused the triangulation work as expected, in the above example, was adding the circular lines. Otherwise, it would have flattened rounded sections, and you would have gotten unexpected results. 
You just have to get used to thinking in the sense of 20 polygons and check if all polygons have all the necessary lines to make it a closed polygon. 

Filling parts separately 

In addition to the topology benefits already mentioned above for using a constrained triangulation algorithm, filling and merging adjacent parts is also possible only because of the triangulation’s restricted nature. 
Suppose you can only fill a single 2D plane at a time, in this case, if the adjacent surfaces share the same edges, you can fill them separately and safely merge them. You just need to apply the removed duplicates, and you have a manifold mesh; This is how it works with many CAD software, and you can find yourself doing the same in SelfCAD when dealing with complex shapes, whereby the 3D pathfinding gives less than perfect results. 

How can fill polygons work on open paths?

SelfCAD’s pathfinding algorithm tries to close open paths when it can find such a solution; this means that you can often find the fill polygon and other tools that are traditionally not supposed to work on open paths, work in SelfCAD. Still, it’s a good practice to close it as this is the industry default, resulting in a managed triangulation output. 

Polygon orientation-flipped normals 
Each polygonal mesh has a clockwise or counterclockwise orientation that also determines which side of the face is pointing to the camera. In some complex cases, the triangulation can flip the order. It, not a big deal, you just have to flip them back. 
SelfCAD has a Backface culling feature that helps see all flipped faces, and SelfCAD has a Flip normals Tool that will check all Faces are in the same orientation and automatically flip them. We elaborate more on this in the topology fixing articles. 

Other tools to create 3D Objects 

We have already illustrated above how the Follow Path feature creates a mesh. We are left to explain the loft and revolve. Both tools work with contours, but they have an entirely different flow and topology structure. Before going into details and explaining some usability tips and tricks, let’s first compare how we create similar shapes using each tool to get an idea of how they work. 

Revolve and Loft 

The Loft tool provides flexibility for creating organic shapes, but you often need to create too many profiles. Revolve, on the other hand, works with a single profile that is much easier to draw. Still, because revolve is using a circular pattern, it is limited to creating circular shapes. 

How to use Revolve

Revolve takes a profile and uses it to extrude and create the additional geometry pieces following a circular pattern. Revolve works on open and closed paths. SelfCAD automatically tries to find the rotation pivot and gives an option to select any other line segment manually. 

Depending on the position of the profile, it may require flipping the normals. The software will change color when this happens. You just need to check or uncheck the flip normals box accordingly.  

Revolve is keeping all geometry details from the sketch drawing. If you need to split your final object, you can simply add a vertex to divide the profile, and the final mesh will have the same Topology structure accordingly. You can add a vertex using the drawing or with the Add Details tool. This behavior is similar to the constrained triangulation we discussed earlier. 

How to convert Arcs and Splines to Segments

If you need to select a curve or spline as the revolve rotation axis, you will first need to convert them into edges. That’s the standard in most CAD software. You can convert splines into line segments using the resolution tool. Most tools in the Modify section will also convert arcs and splines into edges. 

How to use Loft 

Loft uses a weighted function to interpolate the geometry between all segments. It may add more vertices, as needed. The Loft feature is one of the most used tools for creating organic shapes. We already mentioned above about the optional bevel and twisting effects in SelfCAD’s Loft tool. Still, the core features are much more potent than these. 

In the above video, you can see how the designer created a Corona Mask using the loft tool. The designer used it with technical drawings and guides. The fact that you can use it with such precision makes it an excellent tool for mechanical engineers and other designers that need an organic shape, still they need it with utmost precision. 


You can see how we lofted 3D twisted profiles in the above example, unlike the fill polygon tool feature. The loft is not limited to planar surfaces.  

Triangulation vs. Loft 
You can only triangulate the above example profiles after adding many inner lines, thereby dividing the surface into 2d polygon segments. That’s, however, not the case with loft. The fact that Loft can freely interpolate and add necessity vertices enables it to loft even very complex surfaces. You only provide the outer path like in the above example. 

Revolve vs. Loft 
You can technically use Loft to create any shape that you can create using revolve but revolve offers a better option for complex circular shapes as It’s much easier to create a single profile for revolving. Revolve will also create a circular pattern topology structure, much like circular primitives, whereby Loft uses contours and planes, similar to how we create planar objects, and that makes a big difference in the topology structure. Still, it all depends on what you are trying to design. 

Technical Drawing 
You can enter measurements in all drawings using the text box on the bottom left corner.  However, technical drawing often requires additional instruments for measurements, and this is where SelfCAD’s Guides and Measurement tools come into play. 
You can use Guides to position lines, with printed distance or angle measurements. You can then snap the drawing to any point in the guide, as long as you check them as a snapping option in the precision settings. 
You can also add segments to the guides; this is very helpful when you need to subdivide a drawing equally along a measured line, or arc. 
The Measurements tool, on the other hand, is not positioning any guides on the viewport. It’s just printing the measurements in the text box on the bottom left corner; this helps get a precise unit distance between two existing drawing points or an angle between three given points. 
The most fantastic feature of the measurement tool is that you can also change the angle and length from any measurement, and that will automatically move and adjust the related points.
You can set how to reposition the points. You can choose from the starting point, endpoint, or both, and it will adjust the vertices accordingly. 

The above image illustrates on the left a simple line as a guide; it also demonstrates an angle Guide, as well as a subdivided Guide. You also see how the measurement printed an initial value and how changing the value repositioned the related vertices. We set it to Both; hence it adjusted both vertices equally.   

Image to 3D
SelfCAD also offers an Image-To-3D tool as another way to create 3D objects. The Image to 3D is not the best option to incorporate into an optimized topology design flow. It’s an excellent tool for making Logo Designs for Business.  It’s an exceptional tool for designs that do not need many modifications, such as this Ivy Vase, and its primary use case is for making a nice Lithophane.

In conclusion 
You can design in SelfCAD anything that you can make in the most advanced and costly CAD software. SelfCAD has just simplified all and is, therefore, using a different flow. Once you learn it, you will find them much more convenient and much faster to model than in traditional CAD software. SelfCAD has the shortest learning curve from all professional CAD software, and its intuitive design flow attracts beginners and professionals alike. 

Have any questions regarding this article? Feel free to ask us on Reddit and we will be glad to help!

No comments:

Post a comment

Bottom Ad [Post Page]