In CAD systems, models are often rendered not "polygons". There are no triangles, no edges between them, is not the usual textures and UV coordinates. There is a calculation of curves and surfaces in the parameters used when building the model. More complex math for graphics. Because often CAD packages work faster at professional graphics cards, like Nvidia QUADRO, because these cards can hold may be less simulation than arcade, but the calculations are more complicated.
All the other "why" addressed to developers of specific software. Why visualization is bad, why the calculations are on the GPU, why not optimize the display of 3D models for fast rendering, etc. But usually the answer is one - it is necessary to nobody. If the software for creation of boards, from the Board creates, but does not make a beautiful "picture".
travon_Conroy answered on April 19th 20 at 12:26
In gaming technology, the stage is compiled. It is necessary that in real-time the calculation was as quickly as possible. This is achieved through the assumption that 80% of the objects of the game world - fixed. As a rock and not moving. It is through them achieved the lion's share acceleration. This was implemented in the 1990s during the development of Quake. The whole scene is compiled into a special data structure. +Gaming technology weaken the accuracy in favor of special effects. Part of visual effects is not real but simulated through 2D. For example disco ball are not true almost always. And reflects the ambient is also specially pre-compiled. Since compilation time is not a pity - the scene can be pre-processing at least a week. Home to gamer happy.
As in CAD systems of any model element - it is possible to move such approach does not roll. The main task of engineering. And engineer do not care about the special effects. Him if you want to know 20 years ago it was enough of a paper sheet and 4 projections.
Javonte_Beahan answered on April 19th 20 at 12:28
Well, and draw in unreal. Tasks have different SOFTWARE and therefore slow.
Lori.Runolfss answered on April 19th 20 at 12:30
Look at this simple Assembly.
Any game engine would just die. Because of the polygons close to each other.
Well, Kady still a bunch of things to do, except this.