Drawing

Drawing in modern CAD typically can be done in two ways – automated drawings generation using 3D parts and assemblies, and drawing from scratch manually. The two methods can be used together – some drawing elements are generated according to the existing 3D images, others (interactive elements) are created directly in the drawing module. An important feature of advanced drawing applications is variational approach - ability to link drawing elements with logic and parametric constraints. These links are primarily organized between interactive elements as well as between interactive and generated elements for correct positioning of the former with regard to the latter. In principle, such a variational functionality of the drawing module is similar to the functionality of an editor of 2D sketches. Another valuable feature of drawing applications is an ability to use driving dimensions. By superimposing such a dimension (radius, distance, angle) upon drawing elements generated according to a 3D model, users can link it to the original 3D model – in this case, changing dimension parameters results in changing the form of the 3D model. Technically, such a link is exercised by associating the controlled dimension with a parametric constraint, imposed upon one of the 2D sketches that were used to build features of a 3D model.