Traditional modeling techniques that are used in computer graphics have been based on the assumption that objects are, in essence, a set of smooth surfaces, which can be mathematically described by a deterministic function. The simplest of these methods assumes that the objects - is a collection of polygons, the surface is described by a linear function [6]. Natural objects such as rocks, clouds, trees, landscape and do not have the correct form. Most of the events for which you want to build a virtual model are stochastic in nature. This means that they play the traditional means of rendering will be very difficult and resource intensive.
Particle system - used in computer graphic way to represent objects that have no clear geometric boundaries [3]. Examples of such phenomena can be explosions, fog, surface water, flash, falling leaves, clouds, smoke, snow, meteor rain.
The scope of the development associated with multimedia applications for the simulation of chaotic and uncertain effects, which are periodic nature, are difficult to reproduce using conventional imaging technology. Different software products properties appearance and behavior of such systems may be fundamentally different. Currently (September 2010) there is no generally accepted implementation of such systems.
Thus, the topic of master's work, aimed at reducing the time of generation of visual effects that improve the quality of their display and expansion of their application is relevant.
Object of study systems are generating highly realistic images based on the simulation of particle systems in the existing graphics packages.
Subject of study there are methods to create visual effects.
Purpose and objectives of the study. The aim is to develop tools, providing for its use by scientists and engineers improve the efficiency of innovation through high produtkivnosti processing algorithm and particle rendering in real time.
To achieve this goal in the following tasks:
Below is a picture, showing a GUI editor.
In the study used the following methods: analysis literary sources, the development of tests to check the system and efficiency methods that were used simulation to evaluate effective use of technology and identify its bottlenecks.
3DS Max
In 3DS Max, there are three classes of systems of particles: simple, versatile, and a system of particles independent producers. Versatile and simple system of particles does not differ from each other, except for the way radiation. There are predefined templates that are designed for different situations: SuperSpray, Blizzard and PCloud. Super Spray particle system is perfect for blasting and spray effects. If the scene you want to enter the clouds, moving in parallel, or leaves falling on a vast area, of all the uncontrollable events of particle systems would be the best Blizzard. Template PCloud suitable for scenes in which the particles must originate inside some volume effects, such as fire, collapse, and clouds.
If the desired effect goes beyond templates, you can create a system sobstvennnuyu Editor Particle View, where they can set up different kinds of behavior. If required, the particles can move from one state to another. The main elements of a particle system Particle Flow events are composed of individual operators and inspections. Operators are used for the transfer of such properties of the particles, as the angle of rotation, the material and scale. A test intended for the organization of a new particle behavior.
Benefits enough effective means to create visual effects based on predefined templates.
Disadvantages If the desired effect goes beyond the templates will have to create sobstvennnuyu mathematical model.
Particle Studio
The particle system Particle Studio is unique because it contains managed raster settings. In particular, the developer can use the screen to apply to the geometric shape of the radiator, to determine the speed of the particle emitter. This has its advantages, although this slows down the system. In this system, used mainly procedural approach based on the method of Side Effects' Houdini. At first glance the system seems very complicated, but currently cost justify themselves.
Benefits Integration in graphics engines and in simulation systems. Generates a realistic picture.
Disadvantages High system requirements.
Management position and motion of particles in space is realized by means of the emitter (emitter), which acts as a source of particles. Each emitter has a set of properties that define the behavior of particles in space. Mathematically, each particle is represented as a material point with additional attributes such as speed, color, orientation in space, angular velocity, etc. During the simulated particles, each of which changes its status to a specific, common to all particles in the system, the law which established emitter [3]. After all the calculations, the particle is visualized. Particle can be visualized point, the triangle sprite, or a full three-dimensional model.
To calculate each frame in a sequence of movements, performed the following steps:
Because you are using a procedural model, the system can be programmed to perform any set of instructions in each step. This approach may include any computing operations, which describe the appearance or dynamics of the object. For example, the movement and transformation of particles can be tied to a system of differential equations.
Particles are generated at certain intervals, which is based on the oscillation frequency, the initial coordinates of each particle is determined by the position of emitter and the degree of arbitrariness. Emitter has the following parameters:
- Position in space
- The lifetime of the system
- The lifetime of the particle (given the range of minimum and maximum values)
- The emission
Each particle has a number of parameters specified svoytsvami system:
- Direction
- Angle scatter
- Initial velocity
- Gravity
- Radial acceleration
- Tangential acceleration
- Particle size
- Speed
- Alpha channel nachel and end of life of the particle
- The color at the beginning and end of life of the particle. Given in the format of RGB
In each cycle phase simulation adds new particles are removed and the old parameters are updated "live" particles. The motion of each particle based on matimaticheskoy model the movement of material points, where each particle acts as onnoy.
To describe the motion of a particle we use differntsialnye second-order equation. The law of uniformly accelerated motion is obtained by solving simple differential equations of the form:
The general solution of this equation is given by:
Here C1 and C2 - arbitrary constants corresponding to the initial position and initial velocity. Based on the Frenet trihedral, the acceleration vector can be expanded in a concomitant basis:
where
V
-
the velocity,
-
unit tangent to the trajectory vector directed along the velocity (tangent unit vector)
-
unit normal to the trajectory,
-
unit vector binormal to the trajectory,
R
-
radius of curvature of the trajectory.
An example of the expansion velocity of concomitant basis is shown in Figure 4.
It is known that 
always zero. Vectors 
and 
called tangential (tangential) and normal acceleration, respectively, and sets the parameters for the emitter.
For the calculation was a special class of Vector with overloaded operators, which simplifies operations with vectors.
To display a system of particles in a closed area of the polygon clipping operation is used, which is based on an algorithm Fast Winding Number Inclusion of a Point in a Polygon .
Suppose there is a continuous curve:
C (u) = (x (u), y (u)), for 0 <= u <= 1 and C (0) = C (1)
Also there is a point P outside the curve C. In this case, we define the vector CP (u) = C (u)-P from P to C (u) , and its unit vector W (u) = CP (u) / | CP (u) | which gives a continuous mapping of C to the unit circle S1 thus that it can be represented in coordinates as follows:
W (u) = (cos q (u), sin q (u)) ,
where
Q (u) - a positive angle counterclockwise.
In this case, the rotation number wn is equal to the integer part of the rotation number W (u) around S1 . This corresponds homotopic class S1 and can be calculated using the integral:
If the curve C, as shown in Figure 5, is a polygon with vertices V0, V1 ,..., Vn = V0, , this integral determines the amount of corners that border ViVi + 1 with respect to P . In this case, if qi = angle (PVi, PVi +1) , we obtain:
If a face intersects the positive ray upwards, the intersection is considered positive, and if downward, the intersection is considered negative.
Scientific novelty lies in the developed algorithm simulation of visual effects, ease of use, easy integration modeling system with an interface rendering and the possibility of generating the effect of a given trajectory.
The developed system can easily be integrated into the projects under various platforms.
The developed system is made for use in the real world. Used in a number of computer games for Windows-based PCs and gaming systems Nintendo. Due to separation of the stages of modeling and rendering provided cross-platform system. This allows us to integrate the developed system in the draft, which uses simulation of stochastic processes.
The main scientific results were presented at the Scientific Conference of the Taganrog Institute of Technology, SFU and published in the eleventh International scientific-practical seminar "Experience and prospects of partnership in the field of higher education."