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Blender uses an entirely different paradigm: vertex modelling. The only true geometric primitives in Blender are vertices, edges, and faces. When you insert a "
by mrob 3y ago
Blender uses an entirely different paradigm: vertex modelling. The only true geometric primitives in Blender are vertices, edges, and faces. When you insert a "sphere", you're actually running code to automatically generate vertices that approximate a sphere. There is no inherent "sphereness" to the resulting object. You have to decide how close an approximation you want up front, and if you get it wrong you might have to redo a lot of modelling. This is particularly tricky when it comes to constructive solid geometry (CSG), e.g. drilling a hole in that sphere by subtracting a cylinder from it. You might not have enough vertices to satisfactorily approximate the resulting object, and have to use various manual techniques to subdivide specific polygons in the right places.
CAD supports true curved surfaces. A sphere in CAD is a genuine sphere, and you can decide how accurately to render it independently of your modeling operations. CSG is a core technique in CAD modelling, with no special tricks needed to get good results.
To me, the CAD approach is more intuitive, but it's true that vertex modelling can be very fast when you don't need high precision, so I can see why artists like it.
- moffkalast 3y agoSure, but Blender does support CSG with polygons easily. You can do all typical CAD operations, modifiers, parametric stuff, you just have to pick your accuracy on the fly, not later when exporting. You do realize that everything eventually gets turned into polygons before production right? Well aside from sheet metal design I guess. I've lost count how many Fusion360 modelers I've seen that can't properly turn their models into a mesh and 3D print curved surfaces with visible polygon banding lol. > vertex modelling can be very fast when you don't need high precision, so I can see why artists like it It's not about speed, it's about control. When making assets for rendering all kinds of wild tricks are sometimes needed that go beyond modelling solid objects, plus adjusting UV coordinates for texturing and the like.
- adastra22 3y agoI think you vastly underestimate the difficulty of performing geometric kernel operations if you think someone could just wing it in Blender. These kernels represent the combined effort of literally generations of engineers solving really difficult edge case scenarios. Of course for artists, accuracy probably doesn't matter.
- moffkalast 3y agoWell I regularly do indeed wing it in Blender. It is poorly suited for conforming to specific measurements out of the box, but with some plugins it's usable enough. Definitely wouldn't imagine it being in spec for any professional usage but for hobbyist maker stuff getting within 100 microns is more than accurate enough. I mean hell, I can't really measure much more accurately with my callipers anyway.
- deleted 3y ago[deleted]
- treflop 3y agoHonestly from the way you are describing your workflow, it sounds like you haven’t actually dipped into parametric design and you’re still creating your models very manually. Let’s say you have a hole in a part and you need it to be a certain distance from an edge. The rookie way is to pull out your calipers and actually measure that distance and put it into the design. But let’s say you know the hole needs to be co-tangent to an invisible line between two other points. In a parametric modeling program, you would say it as it is: this hole is co-tangent to this invisible line which is defined by these two points. …which gives you a HUGE advantage: let’s say you have to move one of the defining points… well because you defined it parametrically, the hole would just magically resize and reorient itself instantly. And let’s say you extended the hole parametrically to another surface… well that would update too. But if you did it the rookie way, you would have to pull out your calipers and re-measure everything. Risky risky too. Have to double check all your measurements all over again. In Blender, because shapes are not actually mathematical shapes, you aren’t going to be able to define co-tangents or constraints or derive any measurements. That’s why, no matter whether you are a hobbyist or a large professional engineering firm, you might much prefer parametric design because it saves you so much time when drawing out or changing the part. It has nothing to do with the precision of your calipers or the precision of your final product. (That said, not all tasks are fit for parametric design. I wouldn’t design a game model or rendered scene with parametric design. I would use Blender. Also to be said, I know there have been attempts to add parametric design to Blender but I’m not familiar with how far they are.)
- numpad0 3y agoIMO you're totally right, but it's nice and more idiot friendly that underlying representation is always geometry based and not polygon based. Fusion 360 lets me unfillet an edge in an imported file just by hitting Backspace, which AIUI that takes more time and skill to do in Blender. It's Illustrator and Photoshop difference, Ai is superior to Ps if you're having to select and move individual brush strokes all the time. Otherwise it's near polar opposite of course.
- dotnet00 3y agoBlender CSG slows down extremely quickly though. Only takes about a dozen boolean modifiers to cause large slowdowns when editing.