GlLineWidth: Difference between revisions

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(Created page with "'''_glLineWidth:''' specify the width of rasterized lines {{PageSyntax}} SUB _glLineWidth (BYVAL width AS SINGLE) void '''_glLineWidth'''(GLfloat {{Parameter|width}}); ; width : Specifies the width of rasterized lines. The initial value is 1. {{PageDescription}} '''_glLineWidth''' specifies the rasterized width of both aliased and antialiased lines. Using a line width other than 1 has different effects, depending on whether line antialiasing is enabled. To en...")
 
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'''_glLineWidth:''' specify the width of rasterized lines
{{DISPLAYTITLE:_glLineWidth}}
The '''_glLineWidth''' statement specifies the width of rasterized lines.




{{PageSyntax}}
{{PageSyntax}}
: '''_glLineWidth''' GLfloat {{Parameter|width}}


  SUB _glLineWidth (BYVAL width AS SINGLE)
  void '''_glLineWidth'''(GLfloat {{Parameter|width}});


 
{{PageParameters}}
; width
* OpenGL is using its own set of variable types to describe its command parameters.
: Specifies the width of rasterized lines. The initial value is 1.
* Use the following table to find the respective QB64 [[Variable Types]].
{{OpenGLTypesPlugin}}




{{PageDescription}}
{{PageDescription}}
 
* OpenGL's documentation is available in several places, so we won't reproduce it here for another time.
'''_glLineWidth''' specifies the rasterized width of both aliased and antialiased lines. Using a line width other than 1 has different effects, depending on whether line antialiasing is enabled. To enable and disable line antialiasing, call {{KW|_glEnable}} and {{KW|_glDisable}} with argument {{KW|_GL_LINE_SMOOTH}}. Line antialiasing is initially disabled.
* The full description for this command can be found at [https://docs.microsoft.com/en-us/windows/win32/opengl/gllinewidth Microsoft Docs] and is also valid for QB64 usage.
 
If line antialiasing is disabled, the actual width is determined by rounding the supplied width to the nearest integer. (If the rounding results in the value 0, it is as if the line width were 1.) If  <math>|\Delta X| \ge |\Delta Y|</math>, ''i'' pixels are filled in each column that is rasterized, where ''i'' is the rounded value of {{Parameter|width}}. Otherwise, ''i'' pixels are filled in each row that is rasterized.
 
If antialiasing is enabled, line rasterization produces a fragment for each pixel square that intersects the region lying within the rectangle having width equal to the current line width, length equal to the actual length of the line, and centered on the mathematical line segment. The coverage value for each fragment is the window coordinate area of the intersection of the rectangular region with the corresponding pixel square. This value is saved and used in the final rasterization step.
 
Not all widths can be supported when line antialiasing is enabled. If an unsupported width is requested, the nearest supported width is used. Only width 1 is guaranteed to be supported; others depend on the implementation. Likewise, there is a range for aliased line widths as well. To query the range of supported widths and the size difference between supported widths within the range, call {{KW|_glGet}} with arguments {{KW|_GL_ALIASED_LINE_WIDTH_RANGE}}, {{KW|_GL_SMOOTH_LINE_WIDTH_RANGE}}, and {{KW|_GL_SMOOTH_LINE_WIDTH_GRANULARITY}}.
 
 
{{PageNotes}}
 
The line width specified by '''_glLineWidth''' is always returned when {{KW|_GL_LINE_WIDTH}} is queried. Clamping and rounding for aliased and antialiased lines have no effect on the specified value.
 
Nonantialiased line width may be clamped to an implementation-dependent maximum. Call {{KW|_glGet}} with {{KW|_GL_ALIASED_LINE_WIDTH_RANGE}} to determine the maximum width.
 
In OpenGL 1.2, the tokens {{KW|_GL_LINE_WIDTH_RANGE}} and {{KW|_GL_LINE_WIDTH_GRANULARITY}} were replaced by {{KW|_GL_ALIASED_LINE_WIDTH_RANGE}}, {{KW|_GL_SMOOTH_LINE_WIDTH_RANGE}}, and {{KW|_GL_SMOOTH_LINE_WIDTH_GRANULARITY}}. The old names are retained for backward compatibility, but should not be used in new code.
 
 
{{PageErrors}}
 
{{KW|_GL_INVALID_VALUE}} is generated if {{Parameter|width}} is less than or equal to 0.
 
 
{{PageUseWith}}
 
{{KW|_glGet}} with argument {{KW|_GL_LINE_WIDTH}}
 
{{KW|_glGet}} with argument {{KW|_GL_ALIASED_LINE_WIDTH_RANGE}}
 
{{KW|_glGet}} with argument {{KW|_GL_SMOOTH_LINE_WIDTH_RANGE}}
 
{{KW|_glGet}} with argument {{KW|_GL_SMOOTH_LINE_WIDTH_GRANULARITY}}
 
{{KW|_glIsEnabled}} with argument {{KW|_GL_LINE_SMOOTH}}




{{PageSeeAlso}}
{{PageSeeAlso}}
 
* [[_GL|SUB _GL]]
[[_GL|SUB _GL]]
{{KW|_glEnable}}




{{PageCopyright}}
{{PageNavigation}}


Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see [http://oss.sgi.com/projects/FreeB/ http://oss.sgi.com/projects/FreeB/].
[[Category:Final]]

Revision as of 12:20, 19 July 2022

The _glLineWidth statement specifies the width of rasterized lines.


Syntax

_glLineWidth GLfloat width


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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