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glCopyPixels

Chapter 3

The rasterization described thus far assumes pixel zoom factors of 1.0. If glPixelZoom is

used to change the x and y pixel zoom factors, pixels are converted to fragments as

follows. If (x

, y

) is the current raster position, and a given pixel is in the ith location in

the jth row of the source pixel rectangle, then fragments are generated for pixels whose

centers are in the rectangle with corners at

+ zoom

i, y

+ zoom

and

+ zoom

(i+1), y

+ zoom

(j+1))

where zoom

is the value of GL_ZOOM_X and zoom

is the value of GL_ZOOM_Y.

Examples

To copy the color pixel in the lower left corner of the window to the current raster

position, use

glCopyPixels(0, 0, 1, 1, GL_COLOR);

Notes

Modes speciﬁed by glPixelStore have no effect on the operation of glCopyPixels.

Errors

• GL_INVALID_ENUM is generated if type is not an accepted value.

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

• GL_INVALID_OPERATION is generated if type is GL_DEPTH and there is no depth

buffer.

• GL_INVALID_OPERATION is generated if type is GL_STENCIL and there is no

stencil buffer.

• GL_INVALID_OPERATION is generated if glCopyPixels is executed between the

execution of glBegin and the corresponding execution of glEnd.

Associated Gets

glGet with argument GL_CURRENT_RASTER_POSITION

glGet with argument GL_CURRENT_RASTER_POSITION_VALID

HP b2600 Reference Guide

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