30 lines
1.1 KiB
Markdown
30 lines
1.1 KiB
Markdown
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# Materials: Commands {#mat_commands}
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## alphafunc
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### Syntax {#syntax}
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**alphaFunc <func>**
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### Overview {#overview}
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Determines the alpha test function used when rendering this surface.
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Valid values are **GT0**, **LT128**, and **GE128**. These correspond to
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**"GREATER THAN 0"**, **"LESS THAN 128"**, and **"GREATER THAN OR EQUAL
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TO 128"**.
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This function is used when determining if a pixel should be written to
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the frame-buffer. For example, if **GT0** is specified, the only the
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portions of the texture map with corresponding alpha values greater than
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zero will be written to the framebuffer. **By default alpha testing is
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disabled.**
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Both alpha testing and normal [alpha
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blending](blendFunc) can be used to get
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textures that have see-through parts. The difference is that
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**alphaFunc** is an all-or-nothing test, while blending smoothly blends
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between opaque and translucent at pixel edges.
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Alpha test can also be used with
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[depthWrite](depthWrite), allowing other
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effects to be conditionally layered on top of just the opaque pixels by
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setting [depthFunc](depthFunc) to equal.
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