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Keyword reference for colour

Question 31 (2002):

I would like to use colour in my solution to Q7. The PROC fg.col in shared_screen.occ looks useful ... however, I am unable to use the shared_screen.occ code. I have the following lines at the top of my source code:

  #INCLUDE "shared_screen.occ"
  #USE "shared_screen.inc"

Many errors are generated relating to this, such as:

  Error-oc-shared_screen.occ(337)- pc subscripted too many times
  Serious-oc- Too many errors, maximum is 100.

What am I doing wrong?

Answer 31:

Sorry - we hadn't told you how to use this package. It's not part of the basic "course" library! Before explaining how to access, let me stress that noone needs to find out about and use this stuff - it's only there to provide a rich set of drawing mechanisms for those who want to do some really fancy animation. Even then, you don't have to use it ... but you will end up inventing something similar.

Something anyone could have done is simply copy those two files:

  libsrc/shared_screen.inc
  libsrc/shared_screen.occ

into the start of your own q7.occ file. Then, your own code could simply use anything defined in them. Note that the order is important - the shared_screen.inc must go before the shared_screen.occ file (which uses protocols and data types defined in shared_screen.inc).

Better would be to copy those files into the same directory as your q7.occ file and start your file with:

  #INCLUDE "shared_screen.inc"
  #INCLUDE "shared_screen.occ"

Again, note the ordering! These directives simply tell the compiler to pull in those files at the point of those #INCLUDEs.

Best is not to copy those files at all and use the library. All you haven't been told is the name of the library - which is "ss". Currently, only PROCs and FUNCTIONS are saveable in kroc libraries, which means that constants, data types, prototcols (etc.) have to be pulled in as #INCLUDEs. Anyway, to do this, your file needs to start with:

  #INCLUDE "ss.inc"
  #USE "ss.lib"

These can be followed, or preceeded, by other library accesses - e.g.

  #INCLUDE "consts.inc"       -- standard course library constants
  #USE "course.lib"           -- standard course library

We're not quite done. When compiling, the occam compiler (invoked by the kroc shell script) will find the relevant files. [Note: those working with the Linux kroc need to ensure their OCSEARCH environment variable is set up correctly.] When doing final linking (also invoked by the kroc shell script), we have to tell the linker where to find the library code. In fact, the kroc script uses the standard gcc (Gnu C Compiler) to do this linking - i.e. something different from OCSEARCH happens. Anyway, the compile command needed is:

  kroc q7.occ -lss

Linux users have always had to do something like this to link in the course library (which the kroc script on Solaris machines has been set up to do automatically). So, on Linux, if you want both libraries linked in to your executable, the command is:

  kroc q7.occ -lss -lcourse

Enjoy!

Keywords: q7 , colour , animation