Transparency Method

The transparency method attribute indicates the method used to apply transparency. The alpha component of the primitive's color is used for transparency computations. If the primitive does not define the alpha value (see PEXOCCSetAlphaBlend), then the default value is determined differently depending on the primitive type. For surface primitives, the default alpha value is 1.0 - transmission coefficient. (The transmission coefficient is part of the reflection attributes.) For back-facing surfaces, when the pipeline state's facet distinguish flag is True, the alpha value is 1.0 - bf transmission coefficient, where the back-facing transmission coefficient is defined by the pipeline state's bf reflection attributes. For all other, non-surface primitives, the default alpha value is 1.0.

PEXlib defines the following transparency methods:

PEXTransparencyNone -
No transparency. (5.2)

PEXTransparencyScreenDoor -
Screen-door transparency. (5.2)

PEXTransparencyAlphaBlend -
Alpha blending. If the implementation supports an alpha buffer, this mode can be used to perform transparency without multipass rendering. Otherwise, the client will have to sort primitives for reasonable results. The blending function used is determined by PEXOCCSetAlphaBlend. (5.2)

PEXTransparencyTwoPass -
Render only those primitives or portions of primitives with an alpha value of 1.0 in the first pass; render (blend) all other primitives in the second pass. (5.2)

PEXTransparencyMultipass -
Meaningful for multipass rendering only; same as transparency method None if multipass rendering not active. The number of passes and the pixels drawn during each pass are controlled by the transparency thresholds renderer attribute. (5.2)

The complete list of renderer attributes is listed in the Renderer Attributes Table.

For an overview about Renderers, see General Information. For a list of all Renderer functions and related topics, see Rendering.