User Tools

Site Tools


gamedev:textureproperties:transparency

Summary

Texture Property Nametransparency
DescriptionDefines the full or masked transparency
Excepted Data Source1 component image
Data Range0 to 1
Default Value1
Affected ModulesGraphic
Linked Propertiestransparency.type

Description

The transparency texture property defines the degree of transparency of a material. Transparent materials allow to see through with varying strength. This texture property defines either a fully transparent material or a masked material (or holed material). Use the transparency.type texture property to define what kind of transparent material this is.

Fully transparent materials are required for semi-transparent objects like dark glass or for example a colored glass window. In this case a pixel covered by the material requires a blending operation between the pixel behind the object and the pixel on the object itself. This produces realistic and nice looking transparent objects but is in general more demanding on the hardware than rendering a fully opaque object. This kind of material should only be used if a correct transparent look is important for an object. In all other cases it is better to use masked transparency instead.

Masked transparent materials are required for opaque objects containing holes. A typical example for such a material is a wire fence. In this case the material behaves like a fully opaque object concerning concerning rendering just with the difference that holes in the object are not rendered. This is a lot faster than using full transparency since object pixels are either drawn and fully cover the objects behind or not drawn at all in which case the objects behind are visible without alteration. The main problem with masked transparent materials is that they tend to look harder than fully transparent materials.

The transparency value is typically an 8 bit image with 1 color component with the data located inside the range from 0 to 1. 0 represents 0% opaqueness (or coverage) while 1 represents a 100% opaqueness. For a fully transparent material values in between 0 and 1 results in a partial coverage allowing the objects behind the material to shine through more or less. For a masked transparent object values less then 0.5 are mapped to 0% transparency (hence a hole and not rendered) while all other values map to 100% transparency (fully opaque and rendered). In this case values except 0 and 1 should be avoided.

The default value for this texture property is 1 hence fully opaque no matter if fully transparent or masked transparent.

Examples

Transparent glass material

Transparent glass material. Example of a fully transparent material. This glass uses 4% transparency hence 0.04 for the transparency texture property.

You could leave a comment if you were logged in.
gamedev/textureproperties/transparency.txt · Last modified: 2012/12/05 18:48 by dragonlord