Alpha: Difference between revisions
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(cleanup...also example was bad because the combine forcefields use additive blending, not alpha channels) |
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'''Alpha''' is an [[integer]] [[variable]] that is often included as the "fourth" number in a [[RGB]] color format. '''Alpha''' is an [[opacity]] rating from 0 - 255, where 0 is completely invisible and 255 is completely visible. In a VMT file, the "$alpha" parameter is normalized from 0 to 1.0 instead. | '''Alpha''' is an [[integer]] [[variable]] that is often included as the "fourth" number in a [[RGB]] color format. '''Alpha''' is an [[opacity]] rating from 0 - 255, where 0 is completely invisible and 255 is completely visible. In a VMT file, the "$alpha" parameter is normalized from 0 to 1.0 instead. | ||
To store an individual alpha value in each pixel, an [[alpha channel]] is used as the fourth channel of the [[TGA]] file. This allows variable opacity, for example, in a single texture, such as the lettered Petrol signs in Half-Life 2. The texture's alpha channel can also be used to define self illumination instead of | To store an individual alpha value in each pixel, an [[alpha channel]] is used as the fourth channel of the [[TGA]] file. This allows variable opacity, for example, in a single texture, such as the lettered Petrol signs in Half-Life 2. The texture's alpha channel can also be used to define self illumination instead of opacity. | ||
Revision as of 12:13, 15 July 2005
Alpha is an integer variable that is often included as the "fourth" number in a RGB color format. Alpha is an opacity rating from 0 - 255, where 0 is completely invisible and 255 is completely visible. In a VMT file, the "$alpha" parameter is normalized from 0 to 1.0 instead.
To store an individual alpha value in each pixel, an alpha channel is used as the fourth channel of the TGA file. This allows variable opacity, for example, in a single texture, such as the lettered Petrol signs in Half-Life 2. The texture's alpha channel can also be used to define self illumination instead of opacity.