HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 72

C glCopyPixels 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 (xr, yr) 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 (xr + zoomxi, yr + zoomy j) and (xr + zoomx(i+1), yr + zoomy (j+1)) where zoomx is the value of GL_ZOOM_X and zoomy 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 See Also glDepthFunc, glDrawBuffer, glDrawPixels, glPixelMap, glPixelTransfer, glPixelZoom, glRasterPos, 72 Chapter 3