简介

用PDT绘制的物体和用MeasureIt测量的尺寸

PDT是为Blender 2.8和所有后续版本设计的。没有针对早期版本的Blender的版本。

The key objective is to make precision modeling easier and more capable in Blender in order to allow Designers of all genres to model accurately.

有趣的是

There is definitely a difference in the way that “CAD Designers” and “Polygon Modelers” work. Polygon Modelers, the traditional Blender users, tend to start off with a basic primitive 3D mesh, like a Cube, or a Cylinder, then start to add Edge Loops to cut it up, to extrude sections to make it more complex, to add “holes” and then work these. They will often use Sub-Division modifiers to make the model more detailed, whereas CAD Designers consider these to largely be unsuitable and reduce accuracy. This means more vertices in the mesh from CAD modeler, but probably about the same after all has been taken into account.

CAD modelers would virtually never trace off a previous drawing, or photograph to model something, they will always work from quoted dimensions only. To this end think about a drawing at a scale of 50:1 - a line of width 0.5mm is effectively 25mm thick in the real world. Many drawings carry the mantra “Do Not Scale” - this is for a reason, old tradition hand-drawn drawings are not necessarily accurately drawn in the first place!

传统的CAD设计师（我用 CAD 这个词指的是被认为是计算机辅助设计的产品，如SolidWorks、AutoCAD、MicroStation等）倾向于制作一个精确的平面环，如支架的正面或建筑物的墙壁，然后将其挤出，或 “翻转 “为一个三维网格。长期以来，人们一直认为这种方法会带来更精确的模型，例如，可以用于3D打印。

PDT aims to introduce this method of working into Blender, for the benefit and inclusion of all genres of CAD Designers and to augment the tools for the Polygon Modeler. It has been developed by a former Mechanical Design Engineer with many years experience in drawing offices, using hand drawing and CAD techniques.

命名法

There is also the situation where CAD Designers and Polygon Modelers use different terms, like Absolute versus World coordinates, Delta versus Incremental, Directional versus Polar. Primitives themselves are also named differently, Vertices, Edges & Faces versus Points, Lines & Polygons - PDT takes care of this by providing a file that users can edit to input their own terms, including their own languages.