Graphics Reference
In-Depth Information
shouldbeconsideredstrongevidenceforthekindofhigh-qualityimagesthatcanbeproducedwithoutresorting
to ray tracing.
One new development that helps to make it possible to render large numbers of strands is the Strand render
optionontheVisualizationtabforhairparticles.WithStrandrender,thepolygonsthatmakeupthehairarecre-
ated on the fly based on the strand's key points. Using Strand render is highly recommended for rendering large
amounts of hair, because it is fast and memory efficient. However, when Strand rendering is used, ray tracing is
not possible on the strands themselves. Instead, you can use buffered shadows. To use buffered shadows, make
sure that your lights are of the Spot type and select Buffer Shadow on the Shadow tab of the Edit buttons area.
On the Shader tab of the hair material, set Translucency to an above-zero value to enable backlighting to shine
through the hair.
Activating Child Simplification with the check box shown in
Figure 6-55
will automatically remove child
particles from portions of the scene that are distant from the camera. The Reference Size value refers to the true
sizeoftheobject. Whentheobject becomes smaller onthescreenthanthissize(inpixels),childparticles begin
toberemoved.TheRatevaluedetermineshowquicklytheydisappear,andtheTransitionvaluedetermineshow
gradually individual child strands disappear, whether they blink out or fade out gradually. Selecting Viewport
also removes strands that fall outside the borders of the viewport. The Simplification options can greatly speed
up your renders and in some cases make renders with a high strand count possible that wouldn't be otherwise.
There are several other new features that give you more options for lighting particles. The Surface Diffuse
option incorporates the mesh surface normals into the calculation of the strand normals, leading to more-uni-
form shading. This can simplify lighting, because the particles will tend to respond to light less like many indi-
vidual objects and more like a consistent single surface. It also can create a pleasing, somewhat impressionistic
lighting effect.
Ambientocclusion(AO)isanattractivelightingeffectwhenusedappropriately,andasmostusersofBlender
know,differentsituations willgetbetterresultsfromeitherraytracedAOorapproximate AO.ApproximateAO
is likely to be your best option for ambient occlusion.
The Bottom Line
Work with emitter particles.
This chapter discussed the options available to you for working with particles
in Blender 2.6. Particles enable the simulation of very small objects such as dust, snowflakes, or insects and
are the basis for smoke simulations and fluid splashes. They are also used by the Explode modifier to control
bits of a broken object that has been exploded.
Master It
YousawhowtousetheExplodemodifierinthischapterandalsohowtousecollisionobjects
to deflect particles. Using both of these tools, set up a simulation of a ball striking a wall and shattering
oncontact. Animate themotionoftheballagainstthewallbyhandandthencontroltheshattering using
particle property settings. Make sure the pieces of the ball collide with the wall and floor convincingly.
Work with boids.
Boids are a method of simulating the behavior of large groups of small living creatures (at
least, small compared to the size of the group), such as swarms of insects, schools of fish, or flocks of birds.
Master It
The options to allow land movement and to allow flight can be animated. Deflection objects
can be used to give walking boid groups a surface over which to walk. Set up a boid system that begins
byswarminglikeantsoverabumpygroundsurfaceandthentakesflightinthemiddleoftheanimation.
Create hair effects with particles.
Hair particles enable you to have a great deal of control over the appear-
ance and behavior of your characters' hairstyles.
