_glAlphaFunc

The _glAlphaFunc statement enables your application to set the alpha test function.

Syntax

_glAlphaFunc GLenum func, GLclampf ref

Parameters

• OpenGL is using its own set of variable types to describe its command parameters.
• Use the following table to find the respective QB64 Variable Types.

Table 2: Relations between the OpenGL variable types vs. C/C++ and QB64. ┌──────────────┬────────────────┬──────────────────────────────────────────┐ │ OpenGL │ C/C++ │ QB64 │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLenum │ unsigned int │ _UNSIGNED LONG │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLboolean │ unsigned char │ _UNSIGNED _BYTE │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLbitfield │ unsigned int │ _UNSIGNED LONG │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLbyte │ signed char │ _BYTE │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLshort │ short │ INTEGER │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLint │ int │ LONG │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLsizei │ int │ LONG │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLubyte │ unsigned char │ _UNSIGNED _BYTE │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLushort │ unsigned short │ _UNSIGNED INTEGER │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLuint │ unsigned int │ _UNSIGNED LONG │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLfloat │ float │ SINGLE │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLclampf │ float │ SINGLE │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLdouble │ double │ DOUBLE │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLclampd │ double │ DOUBLE │ ├──────────────┼────────────────┼──────────────────────────────────────────┤ │ GLvoid (1) │ void │ _OFFSET(any fixed lenght string or _BYTE │ │ │ │ array element) │ └──────────────┴────────────────┴──────────────────────────────────────────┘ Note: If a parameter has an asterisk (*) in front, then it's a pointer to the designated OpenGL variable type, rather than a value of that type. Those must be passed using the _OFFSET(...) notation. E.g. GLuint *anyParam is actually the offset of a _UNSIGNED LONG (~&) variable or array, which must be passed as _OFFSET(anyVar~&) or _OFFSET(anyArr~&()) respectively. (1) This type is regularly only used for pointers (with asterisk (*)) to any byte sized memory data, hence _BYTE or fixed length strings.

Description

• OpenGL's documentation is available in several places, so we won't reproduce it here for another time.
• The full description for this command can be found at Microsoft Docs and is also valid for QB64 usage.

See also

• SUB _GL
• _glBegin, _glBlendFunc, _glClear, _glDepthFunc
• _glEnable, _glEnd, _glGet, _glIsEnabled
• _glStencilFunc

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