Fluid dynamics animation system and method

• US 5,877,777 A
• Filed: 04/07/1997
• Issued: 03/02/1999
• Est. Priority Date: 04/07/1997
• Status: Expired due to Fees

• Current Assignee: SCG Associates, LLC
• Original Assignee: Tyler G. Colwell
• Inventors: Colwell, Tyler G.
• Primary Examiner(s): Nguyen, Phu K.
• Assistant Examiner(s): Vo, Cliff N.
• Application Number:
  US08/838,426
• Time in Patent Office: 694 Days
• Field of Search: 345/419, 345/302, 345/473, 345/474, 345/475, 364/578
• US Class Current: 345/473
• CPC Class Codes: A63F 2300/663 for simulating liquid objects, e.g. water, gas, fog, snow, clouds
• CPC Class Codes: G06T 13/60 of natural phenomena, e.g. rain, snow, water or plants
• CPC Class Codes: G06T 2210/24 Fluid dynamics

Abstract

The described system and method provide for the creation of realistic wave fronts and spray from one or more user-defined objects impacting on or moving on the surface of a user-defined body of fluid, e.g. water, without using the Navier-Stokes equations. A novel fluid dynamics model is used which requires only the solution of a small set of simple pressure and flow equations. The model involves an array of volumetric cells each in fluid communication with plural neighboring cells, wherein the height of each at each time interval is updated to represent the surface of a fluid body, and objects therein or impact thereon are treated as one or more pressure vectors acting on a given cell in the array. The change in volume of each cell, and its corresponding change in height, is straightforwardly calculated for each unit of time, and the average height at each of the array'"'"'s vertices is used to build a dynamically changing wire-frame grid that represents the surface of the fluid body. The calculations required are straightforward and involve no differentials or integrals. Instead, the calculations require simple arithmetic operations that can be performed quickly in a single iteration for each of only three equations involving pressure on a given cell and fluid communication with neighboring cells. The invented animation system provides easy-to-use tools for creation of such fluid dynamic renditions, preferably as a software plug-in module to the already capable 3D Studio MAX® animation tool kit operating under Windows® 95 or NT.

Claims

1. A system for creating an animated depiction of a fluid body'"'"'s surface response to an animated depiction of an object in contact therewith, the apparatus comprising:

a computer-implemented hydrodynamic model including a defined wire-frame mesh defining a two-dimensional regular array of adjacent volumetric fluid cells each subject to external pressure from at least one neighboring cell and from an object in contact with the animated depiction of the fluid body'"'"'s surface;

a computational mechanism operatively coupled with said hydrodynamic model for deriving the height of each of said cells in said array based upon said hydrodynamic model at predefined times; and

a display generator operatively coupled with said computational mechanism for creating an animated rendering of the fluid body'"'"'s response to contact with the object by manipulating said mesh to represent changes in the heights of said cells at said predefined times.

2. The system of claim 1, wherein said computational mechanism involves no solution to Navier-Stokes-type equations.

3. The system of claim 1, wherein the computational mechanism fluid dynamics properties including the change in height as between pairs of adjacent cells within the array over a given time interval as affected by the contact by the object with the fluid body.

4. A fluid dynamics animation method comprising:

describing a fluid body as a regular array of fluid cells defined by a memory-based mathematical model, said mathematical model describing the fluid dynamics properties representing flow between each cell and its plural adjacent cells within the array;

defining an object impinging upon the fluid body as a plurality of pressure vectors within a vector profile representing the impingement of the object thereon;

calculating the effect on the fluid body by flow between such cells within the mathematical model as influenced by the pressure vectors defining the impinging object; and

rendering a sequence of picture frames based upon said calculating step that, when displayed in rapid succession give the illusion of fluid motion of the fluid body and the impinging object.

5. The method of claim 4, wherein the impinging object produces wave motion in the fluid body.

6. The method of claim 5, wherein the impinging object impacts the fluid body.

7. The method of claim 5, wherein the impinging object travels along the surface of the fluid body.

8. The method of claim 5, wherein the impinging object produces spray phenomena in the fluid body.

9. The method of claim 4, wherein said calculating step includes no solution to Navier-Stokes-type equations.

10. The method of claim 4 which relies solely on the fluid dynamic principle of static equilibrium as between any two adjacent ones of such cells.

11. The method of claim 4, wherein said describing step defines a mathematical model characterized by fluid dynamics properties including the change in height as between pairs of adjacent cells within the array over a given time interval as affected by the impingement of the object on the fluid body.

12. The method of claim 11, wherein said calculating step produces a height for each cell in the array at the end of a defined time interval and then, as among groups of cells having a common vertex therebetween within the array of cells, produces a height for such common vertex at the end of the defined time interval that represents an average of the calculated heights of the cells within each group.

13. The method of claim 4, wherein said defining and calculating steps are repeated, with interactive input from a user of said method regarding the object and its impingement upon the fluid body, prior to said rendering step.

14. The method of claim 13, wherein said describing, defining and calculating steps produce a wire-frame representation of how the object and the fluid body interact as a result of the impingement of the object on the fluid body, the wire-frame representation simulating the fluid dynamics.

15. The method of claim 14, wherein said rendering step produces a smooth texturing of the object and the fluid body to produce the sequence of frames characterized by realistic physical attributes in the animation.