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53 lines
1.4 KiB
Markdown
53 lines
1.4 KiB
Markdown
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**_glViewport:** set the viewport
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## Syntax
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;QB64:SUB _glViewport (BYVAL x AS LONG, BYVAL y AS LONG, BYVAL width AS LONG, BYVAL height AS LONG)
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;C/C++:void **_glViewport**(GLint x, GLint y, GLsizei width, GLsizei height);
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; x, y
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> Specify the lower left corner of the viewport rectangle, in pixels. The initial value is (0,0).
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; width, height
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> Specify the width and height of the viewport. When a GL context is first attached to a window, width and height are set to the dimensions of that window.
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## Description
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**_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:
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glapi viewport equations
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Viewport width and height are silently clamped to a range that depends on the implementation. To query this range, call [_glGet](_glGet) with argument [_GL_MAX_VIEWPORT_DIMS](_GL_MAX_VIEWPORT_DIMS).
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## Error(s)
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[_GL_INVALID_VALUE](_GL_INVALID_VALUE) is generated if either width or height is negative.
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## Use With
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[_glGet](_glGet) with argument [_GL_VIEWPORT](_GL_VIEWPORT)
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[_glGet](_glGet) with argument [_GL_MAX_VIEWPORT_DIMS](_GL_MAX_VIEWPORT_DIMS)
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## See Also
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[_GL](_GL)
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[_glDepthRange](_glDepthRange), [_glViewportArray](_glViewportArray), [_glViewportIndexed](_glViewportIndexed)
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