GlDepthRange: Difference between revisions

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(Created page with "'''_glDepthRange:''' specify mapping of depth values from normalized device coordinates to window coordinates {{PageSyntax}} :: SUB _glDepthRange (BYVAL zNear AS DOUBLE, BYVAL zFar AS DOUBLE) :: void '''_glDepthRange'''(GLdouble {{Parameter|nearVal}}, GLdouble {{Parameter|farVal}}); :: void '''_glDepthRangef'''(GLfloat {{Parameter|nearVal}}, GLfloat {{Parameter|farVal}}); ; nearVal : Specifies the mapping of the near clipping plane to window coordinates. The init...")
 
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'''_glDepthRange:''' specify mapping of depth values from normalized device coordinates to window coordinates
{{DISPLAYTITLE:_glDepthRange}}
The '''_glDepthRange''' statement specifies the mapping of z values from normalized device coordinates to window coordinates.




{{PageSyntax}}
{{PageSyntax}}
: [[_glDepthRange]] GLclampd {{Parameter|zNear}}, GLclampd {{Parameter|zFar}}


::  SUB _glDepthRange (BYVAL zNear AS DOUBLE, BYVAL zFar AS DOUBLE)


::  void '''_glDepthRange'''(GLdouble {{Parameter|nearVal}}, GLdouble {{Parameter|farVal}});
{{PageParameters}}
::  void '''_glDepthRangef'''(GLfloat {{Parameter|nearVal}}, GLfloat {{Parameter|farVal}});
* 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]].
; nearVal
{{OpenGLTypesPlugin}}
: Specifies the mapping of the near clipping plane to window coordinates. The initial value is 0.
; farVal
: Specifies the mapping of the far clipping plane to window coordinates. The initial value is 1.




{{PageDescription}}
{{PageDescription}}
 
* OpenGL's documentation is available in several places, so we won't reproduce it here for another time.
After clipping and division by ''w'', depth coordinates range from -1 to 1, corresponding to the near and far clipping planes. '''_glDepthRange''' specifies a linear mapping of the normalized depth coordinates in this range to window depth coordinates. Regardless of the actual depth buffer implementation, window coordinate depth values are treated as though they range from 0 through 1 (like color components). Thus, the values accepted by '''_glDepthRange''' are both clamped to this range before they are accepted.
* The full description for this command can be found at [https://learn.microsoft.com/en-us/windows/win32/opengl/gldepthrange Microsoft Docs] and is also valid for QB64 usage.
 
The setting of (0,1) maps the near plane to 0 and the far plane to 1. With this mapping, the depth buffer range is fully utilized.
 
 
{{PageNotes}}
 
It is not necessary that {{Parameter|nearVal}} be less than {{Parameter|farVal}}. Reverse mappings such as ''nearVal'' = 1, and ''farVal'' = 0 are acceptable.
 
The type of the {{Parameter|nearVal}} and {{Parameter|farVal}} parameters was changed from GLclampf to GLfloat for '''_glDepthRangef''' and from GLclampd to GLdouble for '''_glDepthRange'''. This change is transparent to user code.
 
 
{{PageUseWith}}
 
{{KW|_glGet}} with argument {{KW|_GL_DEPTH_RANGE}}




{{PageSeeAlso}}
{{PageSeeAlso}}
 
* [[_GL|SUB _GL]]
[[_GL|SUB _GL]]
* [[_glBegin]], [[_glDepthFunc]], [[_glEnd]], [https://learn.microsoft.com/en-us/windows/win32/opengl/glgetbooleanv--glgetdoublev--glgetfloatv--glgetintegerv _glGet]
{{KW|_glDepthFunc}}, {{KW|_glDepthRangeArray}}, {{KW|_glDepthRangeIndexed}}, {{KW|_glPolygonOffset}}, {{KW|_glViewport}}
* [[_glViewport]]




{{PageCopyright}}
{{PageNavigation}}

Latest revision as of 00:49, 28 January 2023

The _glDepthRange statement specifies the mapping of z values from normalized device coordinates to window coordinates.


Syntax

_glDepthRange GLclampd zNear, GLclampd zFar


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


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