4.5.Billboarding Using billboards within games
Billboards Using billboards within games
Billboarding Billboarding is a rendering technique that orientates some object (typically a texture mapped quad) towards a defined target (typically the camera). The orientation may be constrained to be along a certain axis.
Billboarding Billboarding is of use as it provides a means of reducing the number of polygons that need to be rendered. This is done by replacing (potentially complex) 3d geometry with an imposter texture. This is not a new technique!
Common type of billboarding Two types of billboarding are commonly encountered: Cylindrical The rotation of the object is restricted to a vector, usually along the positive direction of the Y axis. Spherical No restriction to the orientation of the object is imposed
Billboards: Trees and Vegetation The visual complexity of grass, shrubs, trees, etc. is such that it is often rendered using one or more billboards.
Billboards: Clouds Overlapping billboards provide a very powerful technique for rendering clouds (which cannot be easily defined in terms of a mesh)
Blending together a number of billboards within a set of particle effects can produce impressive explosions effects. • Billboards: Explosions
Billboards: Imposters By capturing and representing 3D objects within the scene as separate images, it becomes possible to render the image (as a billboard) instead of the 3D object, i.e. the imposter is a simplified representation of a complex 3D object. Dynamically-generated imposters are regenerated at runtime by rendering an image of a 3D object to a texture.
Volumetric Billboards Volumetric billboards use volumetric images of an object stored into 3D textures, instead of 2D images as for standard billboards. A rendering approach can visually reconstruct the object, offering parallax effects, reduced popping artefacts, etc.
Directed reading Directed Reading Directed reading concerning billboarding
Directed reading: Read Billboarding Tutorial – for introductory information on how to render cylindrical or spherical billboards. Read Real-Time Cloud Rendering for Games – for an exploration of cloud rendering using billboards. Read Rendering Forest Scenes in Real-Time – for details on reducing large forest scenes using billboards. Read Spherical Billboards and their Application to Rendering Explosions – for information on how spherical billboards can be used for explosions. Directed reading
Directed reading: Read Volumetric Billboards – for more information on volumetric billboard creation/rendering. Read Billboard Clouds for Extreme Model Simplication – for information on using a “billboard cloud” as a means of simplifying a 3D object. Read Dynamic 2D Imposters: A Simple, Efficient DirectX 9 Implementation – for information on how to implement dynamic imposters at: Directed reading http://www.gamasutra.com/view/feature/2501/dynamic_2d_imposters_a_simple_.php
Summary Today we explored: • The variety of uses that billboarding offers within games. To do: • Read the directed reading • Think if you would like to implement any aspect of billboarding within your project?