[net.graphics] question about the tracer

sdh@joevax.UUCP (The Doctor) (08/13/86)

To the man who wrote the ray tracer (I tried reaching you by mail, but I
got everything bounced back).

Like the program.  One problem: Everything comes out very dim. I tried changing
the default for "sam" (contrast) but that didn't help.
To make things brighter, would I change the ambient lighting, or what?

Also Susie doesn't come out at all.  Very indistinct.  Too bad.


After a few fixes, I will post a new version of my program to convert the
output from the ray tracer to 2 level gray.  As it stands, the program will
now use the header in the file for dimensions and produce output suitable
for a Macintosh.  I fixed a minor bug in the ditherer and the output is much
better.  I will also probably add an option for output as a hex bitmap.

To the best of my knowledge, the -S option (for contrast) doesn't work.
I've tried the following:
tracer -S0.9
tracer -S 0.9

That generates errors.  What gives?

Steve Hawley
joevax!sdh

fritzz@net1.UCSD.EDU (Friedrich Knauss) (08/15/86)

In article <235@joevax.UUCP> sdh@joevax.UUCP (The Doctor) writes:
>
>Like the program.  One problem: Everything comes out very dim. I tried changing
>the default for "sam" (contrast) but that didn't help.
>To make things brighter, would I change the ambient lighting, or what?
>
all sam will do is make the bottom plane less contrasty and more white.
to make things brighter try (in main()) raising the lightsource.
you do that by changing MV(0.0,900.0,0.0,ls) to something like
MV(0.0,3000,0.0,ls). I think you'd also want to enlarge the radius if
you did this.

>Also Susie doesn't come out at all.  Very indistinct.  Too bad.

changing the light source should help.

>To the best of my knowledge, the -S option (for contrast) doesn't work.
>I've tried the following:
>tracer -S0.9
>tracer -S 0.9
>
>That generates errors.  What gives?

once again a problem in main().
under case ('S'), there is an
if statement reading as follows:
if(argv[i][2] < '0' || argv[i][2] > 9)
and it should be
if(argv[i][2] < '0' || argv[i][2] > '9')

the option should then be given as -S0.9


f

pearce@calgary.UUCP (Andrew Pearce) (08/18/86)

In article <235@joevax.UUCP>, sdh@joevax.UUCP (The Doctor) writes:
> To the best of my knowledge, the -S option (for contrast) doesn't work.
> I've tried the following:
> tracer -S0.9
> tracer -S 0.9
> 
> That generates errors.  What gives?
> Steve Hawley
> joevax!sdh

The problem is really simple to fix, in the file "tracer.c" there is a typo:

        case ('S'):  /* amount of susie */
            if (argv[i][2] < '0' || argv[i][2] > 9)
                                                 ^
                                                 |
                                              single quote this
                                          or it will always evaluate to be
                                          true.


---------------------------------------------------------------------
	Andrew Pearce
	...{ihnp4,ubc-vision}!alberta!calgary!pearce
	pearce@calgary.UUCP