glViewport

The glViewport function sets the viewport.

void glViewport(
  GLint x,        
  GLint y,        
  GLsizei width,  
  GLsizei height  
);

Parameters

x, y
The lower-left corner of the viewport rectangle, in pixels. The default is (0,0).
width, height
The width and height, respectively, of the viewport. When an OpenGL context is first attached to a window, width and height are set to the dimensions of that window.

Remarks

The glViewport function specifies the affine transformation of x and y from normalized device coordinates to window coordinates. Let (x (nd) , y (nd) ) be normalized device coordinates. The window coordinates (x (w) , y (w) ) are then computed as follows:

Viewport width and height are silently clamped to a range that depends on the implementation. This range is queried by calling glGet with argument GL_MAX_VIEWPORT_DIMS.

The following functions retrieve information related to glViewport:

glGet with argument GL_VIEWPORT

glGet with argument GL_MAX_VIEWPORT_DIMS

Error Codes

The following are the error codes generated and their conditions.

Error Code Condition
GL_INVALID_VALUE Either width or height was negative.
GL_INVALID_OPERATION glViewport was called between a call to glBegin and the corresponding call to glEnd.

QuickInfo

  Windows NT: Use version 3.5 and later.
  Windows: Use Windows 95 and later.
  Windows CE: Unsupported.
  Header: Declared in gl.h.
  Import Library: Link with opengl32.lib.

See Also

glBegin, glDepthRange