{{QBDLDATE:05-20-2022}}
{{QBDLTIME:23:24:35}}
{{DISPLAYTITLE:_glViewport}}
'''_glViewport:''' set the viewport


{{PageSyntax}}

;QB64:SUB _glViewport (BYVAL x AS LONG, BYVAL y AS LONG, BYVAL width AS LONG, BYVAL height AS LONG)
;C/C++:void '''_glViewport'''(GLint {{Parameter|x}}, GLint {{Parameter|y}}, GLsizei {{Parameter|width}}, GLsizei {{Parameter|height}});


; x, y
: Specify the lower left corner of the viewport rectangle, in pixels. The initial value is (0,0).
; width, height
: Specify the width and height of the viewport. When a GL context is first attached to a window, {{Parameter|width}} and {{Parameter|height}} are set to the dimensions of that window.


{{PageDescription}}

'''_glViewport''' specifies the affine transformation of ''x'' and ''y'' from normalized device coordinates to window coordinates. Let (x<sub>nd</sub>, y<sub>nd</sub>) be normalized device coordinates. Then the window coordinates (x<sub>w</sub>, y<sub>w</sub>) are computed as follows:

{{glapi viewport equations}}

Viewport width and height are silently clamped to a range that depends on the implementation. To query this range, call {{KW|_glGet}} with argument {{KW|_GL_MAX_VIEWPORT_DIMS}}.


{{PageErrors}}

{{KW|_GL_INVALID_VALUE}} is generated if either {{Parameter|width}} or {{Parameter|height}} is negative.


{{PageUseWith}}

{{KW|_glGet}} with argument {{KW|_GL_VIEWPORT}}

{{KW|_glGet}} with argument {{KW|_GL_MAX_VIEWPORT_DIMS}}


{{PageSeeAlso}}

[[_GL|SUB _GL]]
{{KW|_glDepthRange}}, {{KW|_glViewportArray}}, {{KW|_glViewportIndexed}}


{{PageCopyright}}


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