[comp.sys.sgi] Shadows in C

UASLISA@VM.UOGUELPH.CA (Lisa Pretty) (04/01/91)

I am beginning to do a little C programming using an IRIS 4D/20
(GR1.1 Bit-plane, Z-buffer options installed).  So far, I have
been able to use different lighting models and materials to create
lighting animations with shading; however, I have not been able to
create shadows.

Is there anything in the Graphics library which will enable shadows?  If
not, could somebody point me in the right direction (I do have the
Graphics Library Manuals)?

                               Thanks in Advance

                                    Lisa Pretty
                                    uaslisa@vm.uoguelph.ca

mberger@RELAY.NSWC.NAVY.MIL (04/02/91)

The spider demo has a shadow capability.

Also, The Iris Universe magazine (winter 1989) has an article title:
   casting shadows on flat surfaces

A paragraph from the article states:
   The easiest way to flatten an object is to use the scal function.  If
   the ground is the plane formed by the x and z axes (y=0) then:
   scale(1.0,0.0,1.0) could be used to create a shadow from a light shining
   straight down the y axis.
If you can't find the article I could FAX it to you.