Particle Systems

A particle system is basically a technique used in graphic design and gaming physics which allows you to use a large number of very small sprites (computer graphics manipulated to move as a single entity) to simulate 'fuzzy' phenomena, these 'fuzzy' phenomena are otherwise incredibly difficult to replicate with conventional rendering techniques. Creating things such as fire, smoke, fog, explosions etc. are the most common designs used in this area as it is hard to make them realistic without, it gives a more realistic image in the final render.


Examples of which are commonly replicated using particle systems include fire, explosions, smoke, moving water (waterfall), sparks, falling leaves, clouds, fog, snow, dust, meteor tails, stars and galaxies, or abstract visual effects like glowing trails, magic spells, etc. - these use particles that fade out quickly and are then re-emitted from the effect's source. Another technique can be used for things that contain many strands - such as fur, hair, and grass - involving rendering an entire particle's lifetime at once, which can then be drawn and manipulated as a single strand of the material in question. Particle systems may be two-dimensional or three-dimensional.

Typical implementation

Typically a particle system's position and motion in 3D space are controlled by what is referred to as an emitter. The emitter acts as the source of the particles, and its location in 3D space determines where they are generated and where they move to. A regular 3D mesh object, such as a cube or a plane, can be used as an emitter. The emitter has attached to it a set of particle behavior parameters. These parameters can include the spawning rate (how many particles are generated per unit of time), the particles' initial velocity vector (the direction they are emitted upon creation), particle lifetime (the length of time each individual particle exists before disappearing), particle color, and many more. It is common for all or most of these parameters to be "fuzzy" — instead of a precise numeric value, the artist specifies a central value and the degree of randomness allowable on either side of the center (i.e. the average particle's lifetime might be 50 frames ±20%). When using a mesh object as an emitter, the initial velocity vector is often set to be normal to the individual face(s) of the object, making the particles appear to "spray" directly from each face but optional.

Static Particles

Static Particles do not have animation but can be assigned physics, a good example of static particles are hair and grass, Hair particles are each stand of hair, the hair can be given physics to move in the wind or react to movement. grass can be given similar physics but are made with more stiffness so the particles are not just flopping down unrealistically.

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