公开(公告)号：CA1305556C

公开(公告)日：1992-07-21

申请号：CA581528

申请日：1988-10-27

Applicant: IBM

Inventor： CALLAHAN ROBERT M ,  HEMPEL BRUCE C

IPC: G06T11/80 ,  G06F3/033 ,  G06F3/048

Abstract: APPLICATION EXIT FOR POTENTIALLY PICKABLE PRIMITIVES IN A GRAPHICS SYSTEM A method is described which gives local control to an application's display list program during the drawing process when a "pickable" primitive intersects the pick window. This control is provided in such a way that the state of graphics workstation remains unaltered. Thus the application's local display list program is permitted to make "picking" and/or visualization decisions at the moment the pick occurs, and then resume execution of the display program wherever desired (typically, at the graphic instruction following the one that caused the pick). This capability enables application programs to provide greater functionality. usability and productivity their users. KI9-87-017

公开(公告)号：CA1311317C

公开(公告)日：1992-12-08

申请号：CA561202

申请日：1988-03-11

Applicant: IBM

Inventor： CALLAHAN ROBERT M ,  HEMPEL BRUCE C ,  LIANG BOB C C

IPC: G06F15/62

Abstract: A method is described for clipping two and three dimensional graphic primitives for use in a computer graphics workstation. During the first clipping stage, the system removes all graphic primitives which lie outside an arbitrary clipping volume or window that is an enlargement of the desired viewing volume or window. This clipping volume (window) is then projected and mapped onto a virtual viewport which is larger than the real viewport. After this mapping occurs, rendering effects (such as line styles, line width, pattern fill, hatch fill, etc.) are applied to the primitive. A subsequent stage of clipping is then applied to clip the virtual viewport to the real viewport which is the user's visible area. Use of the clipping volume (window) during the first stage of clipping makes it simpler to transform geometric primitives which are partially visible to the viewer, and gives visible primitives a richer set of invariant geometric properties so that their rendering effects may be more easily and correctly carried out. KI986-023

公开(公告)号：CA1304824C

公开(公告)日：1992-07-07

申请号：CA581529

申请日：1988-10-27

Applicant: IBM

Inventor： GONZALEZ-LOPEZ JORGE ,  HEMPEL BRUCE C ,  LIANG BOB C C

IPC: G06F17/50 ,  G06T15/50 ,  G06F15/72

Abstract: A lighting model processing system for a computer graphics workstation's shading function includes multiple floating point processing stages arranged and operated in pipeline. Each stage is constructed from one or more identical floating point processors. The lighting model processing system supports one or more light sources illuminating an object to be displayed, with parallel or perspective projection. Dynamic partitioning can be used to balance the computational workload among various of the processors in order to avoid a bottleneck in the pipeline. The high throughout of the pipeline system makes possible the rapid calculation and display of high quality shaded images.

公开(公告)号：CA1264879A

公开(公告)日：1990-01-23

申请号：CA523775

申请日：1986-11-25

Applicant: IBM

Inventor： HEMPEL BRUCE C ,  LIANG BOB C C

IPC: G06F3/153 ,  G06T11/00 ,  G06T15/30 ,  G06F15/68 ,  G06F15/72

Abstract: A display processor in a raster graphics display system includes a transformation, clipping and mapping feature which controls the transformation, clipping and mapping of graphics data. A control byte contains 5 bits identified as: M- Window to viewport mapping; P-perspective projection; D-2D/3D mode; T-transformation; and C-clipping. Each bit in the control byte is tested to determine what operations are to be performed on the figure to be drawn. For example, if the D bit is one, indicating a three dimensional figure and the T bit is one, indicating transformation, and the C bit is one, indicating clipping, the P bit determines whether the clipping will be perspective or non-perspective clipping and the M bit determines whether the figure to be drawn is to be mapped to the view port.