HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 70

C glCopyPixels glCopyPixels glCopyPixels: copy pixels in the frame buffer. C Specification void glCopyPixels( GLint x, GLint y, GLsizei width, GLsizei height, GLenum type) Parameters x, y width, height type Specify the window coordinates of the lower left corner of the rectangular region of pixels to be copied. Specify the dimensions of the rectangular region of pixels to be copied. Both must be nonnegative. Specifies whether color values, depth values, or stencil values are to be copied. Symbolic constants GL_COLOR, GL_DEPTH, and GL_STENCIL are accepted. Description glCopyPixels copies a screen-aligned rectangle of pixels from the specified frame buffer location to a region relative to the current raster position. Its operation is well defined only if the entire pixel source region is within the exposed portion of the window. Results of copies from outside the window, or from regions of the window that are not exposed, are hardware dependent and undefined. x and y specify the window coordinates of the lower left corner of the rectangular region to be copied. width and height specify the dimensions of the rectangular region to be copied. Both width and height must not be negative. Several parameters control the processing of the pixel data while it is being copied. These parameters are set with three commands: glPixelTransfer, glPixelMap, and glPixelZoom. This reference page describes the effects on glCopyPixels of most, but not all, of the parameters specified by these three commands. glCopyPixels copies values from each pixel with the lower left-hand corner at (x + i, y + j) for 0 ≥ i