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 (xnd, ynd) be normalized device coordinates. The window coordinates (xw, yw) are then computed as follows:
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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. |
Requirements
** Windows NT/2000:** Requires Windows NT 3.5 or later.
** Windows 95/98:** Requires Windows 95 or later. Available as a redistributable for Windows 95.
** Header:** Declared in Gl.h.
** Library:** Use Opengl32.lib.