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glPixelZoom
Chapter 14
337
glPixelZoom
glPixelZoom: specify the pixel zoom factors.
C Specification
void glPixelZoom(
GLfloat xfactor,
GLfloat yfactor)
Parameters
xfactor, yfactor Specify the x and y zoom factors for pixel write operations.
Description
glPixelZoom specifies values for the x and y zoom factors. During the execution of
glDrawPixels or glCopyPixels, if (x
r
, y
r
) is the current raster position, and a given
element is in the mth row and nth column of the pixel rectangle, then pixels whose
centers are in the rectangle with corners at
(x
r
+ n ·xfactor, y
r
+ m ·yfactor)
(x
r
+ (n+1) ·xfactor, y
r
+ (m+1) ·yfactor)
are candidates for replacement. Any pixel whose center lies on the bottom or left edge of
this rectangular region is also modified.
Pixel zoom factors are not limited to positive values. Negative zoom factors reflect the
resulting image about the current raster position.
Errors
• GL_INVALID_OPERATION is generated if glPixelZoom is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_ZOOM_X
glGet with argument GL_ZOOM_Y
See Also
glCopyPixels,
glDrawPixels
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