Method of rendering a two-dimensional image to a designer

A computer program comprising instructions that, when executed on a computer, cause the computer to:

• receive a definition of a two-dimensional image plane in which to view a two-dimensional rendered image and either a viewpoint from which to view the two-dimensional rendered image or a view direction;
• receive a viewport lying in the two-dimensional image plane and representing a desired portion of the two-dimensional image plane that a designer wishes to view;
• define, in a viewport proto-space, a parameterization of a set of viewport planes that extend from the viewport towards the viewpoint or parallel to the view direction to create a three-dimensional form by selecting a point in each viewport plane of the set of viewport planes, wherein the viewport and the set of viewport planes are associated with a transform from the viewport proto-space to a three-dimensional assembly space;
• generate, in quadruple precision, a combined transform comprising a transform associated with a part instance in an assembly, the transform associated with the viewport and the set of viewport planes, and a transform to scale the viewport and/or translate the viewport and the set of viewport planes;
• operate on the combined transform and the points defining the viewport planes in double precision to intersect faces and/or edges of at least one part instance in the assembly with at least one of the viewport planes to generate clipping lines and/or clipping points, wherein the clipping lines and the clipping points clip the faces and the edges of the part instance in the assembly to a portion of the assembly that lies within the viewport;
• and
• output a rendering of a two-dimensional image of the assembly of part instances, wherein the clipping lines and/or the clipping points are used to restrict the rendering to portions of the assembly that lie within the viewport.

A data processing system configured to render, to a designer, a two-dimensional image of an assembly of part instances in a three-dimensional assembly space within a computer-aided design (CAD) system utilizing double precision to describe part assemblies, wherein each part instance of the part instances in the assembly is associated with a proto-space and a transform that transforms a respective part instance from the proto-space of the respective part instance to the three-dimensional assembly space, the data processing system comprising:

• a designer input device configured to:
• receive a definition of a two-dimensional image plane in which to view a two-dimensional rendered image and either a viewpoint from which to view the two-dimensional rendered image or a view direction;
• and
• receive a viewport lying in the two-dimensional image plane and representing a desired portion of the two-dimensional image plane that the designer wishes to view;
• a data processor configured to;
• define, in a viewport proto-space, a parameterization of a set of viewport planes that extend from the viewport towards the viewpoint to create a three-dimensional form by selecting a point in each viewport plane of the set of viewport planes, and the viewport and the set of viewport planes being associated with a transform from the viewport proto-space to the three-dimensional assembly space;
• generate, in quadruple precision, a combined transform comprising a transform associated with the part instance in the assembly, the transform associated with the viewport and the set of viewport planes, and a transform to scale the viewport and/or translate the viewport and the set of viewport planes;
• and
• operate on the combined transform and the points defining the viewport planes in double precision to intersect faces and/or edges of at least one part instance in the assembly with at least one of the viewport planes to generate clipping lines and/or clipping points, wherein the clipping lines and the clipping points clip the faces and the edges of the part instance in the assembly to a portion of the assembly that lies within the viewport;
• and
• a graphics system configured to output a rendering of the two-dimensional image of the assembly of part instances, wherein the clipping lines and/or the clipping points are used to restrict the rendering to portions of the assembly that lie within the viewport.