glViewport

glViewport

NAME

glViewport -- set the viewport

C SPECIFICATION

void glViewport(GLint x,

GLint y,

GLsizei width,

GLsizei height)

PARAMETERS 参数说明

x, y

Specify the lower left corner of the viewport rectangle, in pixels. The default is (0, 0).

指定视口矩形左下角，以像素为单位。默认值为（0，0）。指定视口矩形左下角，以像素为单位。默认值为（0，0）。

width, height

Specify the width and height, respectively, of the viewport. When a GL context is first attached to a window, width and height are set to the dimensions of that window.

分别指定宽度和高度。根据窗口的实时变化重绘窗口

DESCRIPTION

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:

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.

ERRORS

GL_INVALID_VALUE is generated if either width or height is negative.

GL_INVALID_OPERATION is generated if glViewport is executed between the execution of glBegin and the corresponding execution of glEnd.