Museum

     readRGB(3G)                                           readRGB(3G)



     NAME

          readRGB - returns values of specific pixels


     SPECIFICATION

          C         long readRGB(n, red, green, blue)

                    short n;

                    RGBvalue red[], green[], blue[];




          FORTRAN   integer*4 function readRG(n, red, green, blue)

                    integer*4 n

                    character*(*) red, green, blue


     DESCRIPTION

          readRGB attempts to read up to n pixel values from the

          bitplanes in RGB mode.  It reads them into the red, green,

          blue arrays starting from the current character position

          along a single scan line (constant y) in the direction of

          increasing x.  readRGB returns the number of pixels actually

          read, which is the number specified in n if the starting

          point is at least that number away from the edge of the

          screen.  The values of pixels read outside the screen are

          undefined.


          readRGB updates the current character position to one pixel

          to the right of the last one read; the current character

          position is undefined if the new position is outside the

          viewport.  In RGB double buffer mode, only the back buffer

          is read.


          readRGB is available only in RGB mode.


     SEE ALSO

          readpixels, writeRGB


          Programming Guide, Section 3.9, Writing and Reading Pixels


     NOTE

          This routine is available only in immediate mode.
















     Page 1                                          (printed 8/20/87)