Can anyone in the SketchUp team explain why SketchUp can’t draw circles and curves. I’ve had all kinds of uninformed explanations in the past, but I need to hear from someone who actually works with and understands the underlying SketchUp code.
Since SketchUp is basically a 2D program, using the assembly of 2D constructions to form 3D models, I need to understand why circles and curves can’t be done. CorelDRAW is a 2D vector drawing program, which draws perfect circles and curves. It can take a polyline and convert it to a curve. Is it too much of a rewrite to make this happen in SketchUp?
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It’s a 3D modeller.
Polygons are not curved.
There are other types of 3D representation that are not constructed from straight edges, but the vast, vast majority of 3D computer visuals are made in this way
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I don’t understand this response. I know that polygons consist of straight edges, which is what makes them polygons. But why are circles in SketchUp polygons?
You say that other types of 3D representations are not constructed from straight edges, but there are only straight lines and flat surfaces in SketchUp.
You need to be more precise.
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The other direction works. If you make something out of curves and circles in SketchUp, you can export as DXF or DWF, and get true curves, as you might want to do when sending something to a CNC machine.
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Yes, I appreciate this, and have done so in the past. But what I’m wondering about is will it ever be available is SketchUp with the need to export?
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SketchUp, like most 3D modeling software, is polygon-based because it allows for efficient rendering, texturing, and animation. Polygons are the standard in real-time graphics and many design workflows because they balance detail and performance.
For users who need precise, mathematically defined surfaces (especially for engineering or manufacturing), a NURBS-based package like SolidWorks, Rhino, or Fusion 360 is a better fit. Those tools specialize in creating smooth, parametric surfaces, which are ideal for CAD work but can be overkill for architectural visualization or concept modeling where SketchUp excels.
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CorelDRAW is strictly 2D, and does no employ NURBS. Try again.
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I didn’t know Corel Draw 2D was a 3D modeller tbh.
It probably uses vectors for its 2D circles.
Who knows what Corel Draw 2D uses for 3D . It’s truly a mystery to me
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What does using vectors mean?
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It’s a bit like 2D Nurbs
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CorelDraw can draw perfect circles and curves. What it displays is what it actually is. A vector, as opposed to vector graphics, is generally considered a direction in the x,y,z direction. A circle drawn in CorelDRAW can be exported as a DXF, and then imported into SketchUp, which SketchUp then converts into a polygon. It’s not a matter of vector graphics, it’s a matter of the SketchUp code. I’m simply trying to find out if it is too difficult for the programmers at Sketchup to work with the underlying code so that SketchUp can draw circles and curves.
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SketchUp stores the information about whether the object is a circle or curve, but in order to push pull said circle into a cylinder it is required to be a polygon because SketchUp is a polygon based 3D modeller.
It sounds like you are trying to use SketchUp for 2D work?
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We are not communicating effectively. Go back to my original post. I need to hear from someone in the SketchUp team. I need an informed answer as to the degree of difficulty in working with the SketchUp code to explain if it is simply too difficult a rewrite to achieve what I’m looking for.
By the way, SketchUp is a effectively a 2D program. There are no such things as 3D elements in SketchUp.
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SketchUp is a 3D surface modeler. It draws circles as polygons. Other software does solid modeling and they can create perfect circles.
Solid modeling software like SolidWorks or AutoCAD can create mathematically perfect circles and curves. These programs use precise geometric definitions, including NURBS.
It would not be easy because SketchUp is a different kind of 3D modeler.
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SketchUp was originally coded to the OpenGL graphics library, which I believe does not offer a built-in function to draw a circle. The usual way is to draw a polygon with a lot of sides, which is what SketchUp does. Changing this now would be a major rework of SketchUp’s internal representation and model database.
Request away, but I think the odds of it happening are low.
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The Qt graphics library may be able to draw circles. So maybe one day!
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No, it’s not. SketchUp is a native 3D environment. The location of points or nodes where edges end or intersect are defined by three values in the classic Cartesian Coordinate System, X, Y, and Z. Yes, the objects in SketchUp are defined by edges and planes which have infinite thinness, but that does not make it a 2D program, because the location of the edges are defined in three directions from each other X, Y, and Z. 2D programs like Corel Draw, or illustrator are vector (a line with length and a direction, look it up) are not operating in the third Z dimension, there is no thickness or height depending on how you look at it, to anything, you cannot look at anything from the side, you are only working with X and Y information for any given point or position, like in flatland (good read). It is fundamentally different.
As has been said, SketchUp (like some other programs) is a polygon based surface modeler, that makes it fast and flexible and totally awesome. It is a function of polygon modeling that all edges are defined in straight lines. The underlying math function is basically a series of nodes or single points in 3D space that can be connected to other points in space, if three or more of those point coexist on a plane then they can be connected and a surface can be formed. You can then connect to other points within 3D space to make all sorts of interesting shapes with straight lines, that’s SketchUp.
Go out to the garage and get a piece of plywood and some nails and some string. Hammer the nails into a circle on the plywood, these are your nodes or points in space, then stretch the string around the nails. It forms a faceted circle because the string forms straight lines between the nails. This is how a polygon modeler functions by “remembering” where the nails or points are in space and which ones are connected. You can make a smoother circle with more nails and smaller straight string lines between them, but you can never make a pure circle with those tools because that’s not how string and nails work, not how geometry works, and not how a polygon modeler works.
That’s all the explanation I have in me before dinner.
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I am totally familiar with every detail of what you have said, and I disagree. Any object this is perfectly flat is 2 dimensional. That is a simple fact. SketchUp is a brilliant program that has figured out how to assemble 2D objects into a 3D model. That’s totally different from a program that employs NURBS to create actual 3D objects. As far as the objects themselves are concerned, there is nothing 3D about SketchUp.
What I’m waiting for is someone from the SketchUp team to discuss the feasibility, or lack thereof, of using Bezier surfaces, without which curved lines would not work in SketchUp.
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Are point clouds 2D?
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