System and method for increasing the performance for real-time rendering of three-dimensional polygonal data

• US 5,973,699 A
• Filed: 09/19/1996
• Issued: 10/26/1999
• Est. Priority Date: 09/19/1996
• Status: Expired due to Term

• Current Assignee: CA, Inc. (d/b/a CA Technologies) (Broadcom, Inc.)
• Original Assignee: PLATINUM Technology IP, Inc. (Broadcom, Inc.)
• Inventors: Kent, James R.
• Primary Examiner(s): Nguyen, Phu K.
• Assistant Examiner(s): Vo, Cliff N.
• Application Number:
  US08/716,543
• Time in Patent Office: 1,132 Days
• Field of Search: 345/418, 345/419, 345/420, 345/421, 345/423
• US Class Current: 345/419
• CPC Class Codes: G06T 15/40 Hidden part removal

Abstract

A process for optimally rendering 3D worlds so that a sufficiently detailed representation of the 3D world is displayed at a frame rate that provides fluidity of motion while maintaining enough context of the world to enable user interaction. A data structure is computed that contains information about how the world is spatially organized. The 3D world is divided into a non-uniform subdivision grid in each of the three dimensions. Each element in the data structure represents one 3D rectangular cell within the spacial subdivision. Each element stores a list of all the objects in the world which occupy any portion of the 3D cell represented by the data element. The subdivision grid and the array are used to determine which portions of the scene are most visually important to the user. An imaginary ray is cast into the subdivision grid from the viewer'"'"'s perspective along the viewer'"'"'s line of sight. The first objects rendered are those within the first cell the ray intersects. The next objects that are rendered are those within the second cell the ray intersects. This continues until all objects within each cell that the ray intersects are rendered. Next, objects that are within cells adjacent to each intersecting cell are rendered. This is followed by rendering objects that are two cells away, and so on, until all object are rendered or the allotted time to render a single frame has expired.

Claims

1. A process for optimizing rendering of polygonal data, representing a three dimensional world capable of being viewed by a user from the viewpoint of a virtual camera, said process comprising the steps of:

constructing a ray having an orientation coinciding with the orientation of the viewpoint of the virtual camera;

prioritizing objects to be rendered according to each of said objects displacement from said ray; and

rendering said objects according to a priority from said prioritizing step.

2. The process of claim 1, further comprising the step of specifying a maximum amount of time in which to render a single frame.

3. The process of claim 2, further comprising the step of repeating said steps of prioritizing and rendering until all said objects that are viewable have been rendered or said maximum amount of time has expired.

4. The process of claim 3, further comprising the step of repeating said process for each frame rendered.

5. The process of claim 1, wherein said prioritizing step includes the steps of:

constructing a subdivision grid comprising a plurality of cells superimposed upon said three dimensional world and;

prioritizing said objects to be rendered based on each of said objects position within said subdivision grid.

6. The process of claim 3, wherein said steps of prioritizing and rendering comprise the steps of:

(a) creating an ordered cell list comprising cells that are intersected by said ray;

(b) rendering said objects that are within at least one cell according to the order and identification of cells as defined by said ordered cell list; and

(c) rendering said objects that are displaced a predetermined number of cells in each direction from each cell comprising said ordered cell list.

7. The process of claim 6 further comprising the step of repeating said process, wherein said predetermined number of cells is one the first time step (c) is processed and is incremented upon each subsequent processing of step (c).

8. A process for optimizing the rendering of polygonal data representing a three dimensional (3D) world having a 3D coordinate system and comprising 3D objects having up to three dimensions, said 3D world capable of being viewed by a user from the viewpoint of a virtual camera, said process comprising the steps of:

constructing a 3D boundary that encloses one or more objects in the 3D world;

creating at least one sorted list of objects comprising the objects enclosed by said boundary, wherein each said sorted list corresponds with a particular dimension or the 3D world;

constructing a subdivision grid according to said sorted list comprising a plurality of 3D cells; and

prioritizing objects within said 3D cells to be rendered according the position of said 3D cells relative to the virtual camera.

9. The process of claim 8, further comprising the step of rendering objects according to the priority of said 3D cells determined in said prioritizing step.

10. The process of claim 9, further comprising the step of repeating said prioritizing and rendering steps until all objects have been rendered.

11. The process of claim 9, further comprising the step of repeating said prioritizing and rendering steps until all viewable objects have been rendered.

12. The process of claim 9, further comprising the steps of:

specifying a maximum amount of time in which to render a single frame;

repeating said prioritizing and rendering steps until said maximum amount of time has expired.

13. The process of claim 8, further comprising the step of creating a 3D array of elements, wherein each element corresponds to one said 3D cell and comprises a list of objects within the corresponding 3D cell.

14. The process of claim 8, further comprising the step of constructing a ray within the 3D world, the orientation of said ray coinciding with the orientation of the viewpoint of the virtual camera.

15. The process of claim 8, wherein said 3D boundary has a generally rectangular shape in each dimension.

16. The process of claim 8, wherein said 3D boundary extends from the origin of the 3D coordinate system.

17. The process of claim 8, wherein said sorted list of objects is sorted according to the distance of each object relative to a predetermined point in the 3D coordinate system.

18. The process of claim 8, wherein said step of constructing a subdivision grid comprises the steps of:

dividing each said sorted list into a number of sublists, thereby creating a divider between said sublists; and

placing subdivision planes within said 3D boundary in each dimension, wherein each said subdivision plane is placed between a pair of objects separated by said dividers.

19. The process of claim 18, wherein said number of sublists is proportional to the spatial extent of the 3D world in the corresponding dimension of said sorted list, relative to the extent of the 3D world in the other dimensions.

20. The process of claim 18, wherein each said sub-list comprises substantially equal numbers of objects.

21. The process of claim 18, wherein each said subdivision plane is placed between the center points of each said pair of objects.

22. The process of claim 14, further comprising the step of prioritizing objects to be rendered according the displacement of said objects from said ray.

23. The process of claim 22, further comprising the steps of:

creating a 3D array of elements, wherein each element corresponds to one said 3D cell and comprises a list of objects within the corresponding 3D cell;

rendering objects according to the priority of said 3D cells from said prioritizing step; and

repeating said prioritizing and rendering steps until all objects or all viewable objects have been rendered, or the time to render a single frame has expired.

24. The process of claim 21, wherein said prioritizing and rendering steps further comprise the steps of:

(a) creating an ordered cell list comprising cells that are intersected by said ray;

(b) rendering the objects within each particular cell according to said ordered cell list, said objects being selected according to said list of objects in said 3D array element corresponding with said particular cell being rendered; and

(c) rendering objects displaced a predetermined number of cells in each direction from each cell rendered in step (b), wherein said predetermined number of cells is 1 the first time step (c) is processed and is incremented upon each subsequent processing of step (c).

25. A system for optimizing the rendering of polygonal data representing a three dimensional (3D) world having a 3D coordinate system and comprising 3D objects having up to three dimensions, said 3D world capable of being viewed by a user from the viewpoint of a virtual camera, said system comprising:

boundary construction means for constructing a 3D boundary that encloses one or more objects in the 3D world;

list creation means for creating at least one sorted list of objects comprising the objects enclosed by said boundary, wherein each said sorted list corresponds with a particular dimension or the 3D world;

grid construction means for constructing a subdivision grid according to said sorted list comprising a plurality of 3D cells; and

prioritizing means for prioritizing objects within said 3D cells to be rendered according the position of said 3D cells relative to the virtual camera.

26. The system of claim 25, further comprising a means for specifying a maximum amount of time in which to render a single frame.

27. The system of claim 25, further comprising rendering means for rendering objects according to the priority of said 3D cells determined from said prioritizing means.

28. The system of claim 26, further comprising means for repeating the operation of said prioritizing and rendering means until said maximum amount of time to render a single frame has expired.

29. A computer program product comprising a computer useable medium having computer program logic stored therein said computer program logic for enabling a computer to optimize rendering of polygonal data representing a three dimensional (3D) world having a 3D coordinate system and comprising 3D objects having up to three dimensions, said 3D world capable of being viewed by a user from the viewpoint of a virtual camera, wherein said computer program logic comprises:

first constructing means for enabling the computer to construct a 3D boundary that encloses one or more objects in the 3D world;

creating means for enabling the computer to create at least one sorted list of objects comprising the objects enclosed by said boundary, wherein each said sorted list corresponds with a particular dimension or the 3D world;

second constructing means for enabling the computer to construct a subdivision grid according to said sorted list comprising a plurality of 3D cells; and

prioritizing means for enabling the computer to prioritize objects within said 3D cells to be rendered according the position of said 3D cells relative to the virtual camera.

30. The computer-program product of claim 29, further comprising means for enabling the computer to specify a maximum amount of time in which to render a single frame.

31. The computer program-product of claim 29, further comprising means for enabling the computer to render objects according to the priority of said 3D cells determined [in] by said prioritizing means.

32. The computer program-product of claim 30, further comprising means for enabling the computer to repeat said prioritizing and rendering means until said maximum time to render a single frame has expired.