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Core in version 4.5
Core since version 1.0

glViewport: set the viewport

Function Definition

 void glViewport(GLint x, GLint y, GLsizei width, GLsizei 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, width and height are set to the dimensions of that window.


glViewport specifies the affine transformation of x and y from normalized device coordinates to window coordinates. Let (xnd, ynd) be normalized device coordinates. Then the window coordinates (xw, yw) are computed as follows:

x_{w}=(x_{{nd}}+1)\left({\tfrac  {width}{2}}\right)+x

y_{w}=(y_{{nd}}+1)\left({\tfrac  {height}{2}}\right)+y

Viewport width and height are silently clamped to a range that depends on the implementation. To query this range, call glGet with argument GL_MAX_VIEWPORT_DIMS​.


GL_INVALID_VALUE​ is generated if either width or height is negative.

Associated Gets

glGet with argument GL_VIEWPORT​

glGet with argument GL_MAX_VIEWPORT_DIMS​

See Also



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