Optimise my ray tracer - comp.lang.java.programmer

Message from discussion Optimise my ray tracer

Lasse Reichstein Nielsen

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More options 2 Jun 2005, 17:31

Newsgroups: comp.lang.java.programmer

From: Lasse Reichstein Nielsen <l...@hotpop.com>

Date: Thu, 02 Jun 2005 18:31:55 +0200

Local: Thurs 2 Jun 2005 17:31

Subject: Re: Optimise my ray tracer

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Jon Harrop <use...@jdh30.plus.com> writes:
> 1. What major optimisations are missing from my program (e.g. in C++, I pass
> vectors by reference and try to inline vector operations).

I'll leave that for now (meaning: I haven't read the program yet :)

Generally, there are several tricks that allows the compiler and
runtime to optimize, like defining variables and field as "final" if
they don't change.

I'm sure Googleing for "java optimizing" will give about a gazillion
links. I know that Peter Sestoft has a file on Java performance on
<URL:http://www.dina.kvl.dk/~sestoft/javaprecisely/>
which I remember as being good.

> 2. Where is the floating-point machine epsilon in the Java libraries?

I'm not sure what epsilon is to you, but you might want
Double.MIN_VALUE, the smalles positive value representable as a
double.

> 3. How do you do infix operators in Java?

You don't. The designers of Java decided early on that they wanted the
*syntax* to always mean the same thing, making it easier to read other
people's programs (in particular, they didn't want #define, and I guess
overriding infix operators were ruled out for the same reason).

> 4. Am I supposed to have a static main function which instantiates a class
> and invokes a member function of it in order to start the program?

The static "main" function *does* start the program. You want to call
the "run" function from it, and since "run" is not static, you need
to create an object before calling it. However, since "run" doesn't
use that object, the "run" function could have been made static as
well. Likewise the other methods on the class "ray" (classes are
traditionally capitalized).

Anyway, I might have time to look at it some more later :)

> Here's my Java port:

[snip]
A link to an online file would take less room here :)

/L
--
Lasse Reichstein Nielsen - l...@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'

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