| Realistically simulating and rendering fluids is an area of computer science that has tantalized computer graphics researchers for years, simply because of the sheer difficulty, and vast range of knowledge that the field encompasses. Simulating rivers is itself a difficult problem within this field because it is one of the more general cases where computational fluid dynamics can be applied. In order to physically model a river the complex interactions between the fluid, air, and the underlying terrain must all be accounted for. And, intending to have this all occur in real-time means that the tactic of applying general, and lengthy, computations to solve the fluid system is not a possibility; some more specific method suited to real-time use is required.;In order to achieve our goal of simulating and rendering a river, in real-time, we took the approach of combining several techniques: a 2D fluid solver that can capture minute details in a river's surface, an efficient method for computing some 3D flow information (which gives the fluid solver just enough information to model the interactions between the water and the terrain, yet remain efficient enough to be computed in real-time), and an animated 3D procedural wave texture that gets advected through the fluid via "advection particles" in order to elicit the highly detailed fluid surfaces that are characteristic of rivers.;Our research, and implementation, shows that the novel technique of coupling an animated texture advection method to a fluid simulation can produce results that are representative of large scale real-world rivers, and that the technique is suitable for use in real-time settings. In one of our test scenes we simulate a ten kilometer long river section at real-time frame rates (60 frames per second) with a grid resolution of 1024x1024 cells. The method is stable (not prone to explosions), and currently has the limitation of only being able to produce planar river surfaces (an efficiency/quality trade-off), however we feel this research presents a successful step toward enabling more large scale dynamic fluid effects in real-time applications. |
