Vectors and matrices in D

[Andreas Zwinkau]

> I started implementing a little raytracer in D (raytracing is addictive, yeah ;)), and faced problems with vector/matrix math :(

Me too :)
I wanted to learn D and to write a raytracer for some time. Currently i have some time to do so. I got a little sidetracked into D templates by the vector implementation.

Every implementation (Artyom, helix, some C++ raytracers) i've seen so far uses a struct for the vectors. Why? Performance? Does Bill Baxter hint at this?
http://www.digitalmars.com/pnews/read.php?server=news.digitalmars.com&group=digitalmars.D&artnum=46958

I wrote a generic vector class. Maybe someone would like to comment on that? I it's just addition and subtraction so far, but the pattern is clear. Here comes my code:

import std.stdarg;
import std.string;

class Vector(T, int S) {
        T[S] content;

        this(...) {
                for (int i = 0; i < _arguments.length; i++) {
                        content[i] = va_arg!(T)(_argptr);
                }
        }

        T opIndex(int i) {
                assert(i < content.length,
                        std.string.format("%d < %d !!!\n", i, content.length));
                return content[i];
        }

        void opIndexAssign(T n, int i) {
                content[i] = n;
        }

        Vector!(T,S) opAdd( Vector!(T,S) other ) {
                Vector!(T,S) n = new Vector!(T,S)();
                foreach(int i, T c; content) {
                        n[i] = c + other[i];
                }
                return n;
        }

        Vector!(T,S) opSub( Vector!(T,S) other ) {
                Vector!(T,S) n = new Vector!(T,S)();
                foreach(int i, T c; content) {
                        n[i] = c - other[i];
                }
                return n;
        }
}

unittest {
        Vector!(int, 2) a = new Vector!(int, 2)(1,3);
        Vector!(int, 2) b = new Vector!(int, 2)(1,2);

        // check addition
        Vector!(int, 2) c = a + b;
        assert(c[0] == 2);
        assert(c[1] == 5);

        // check subtraction
        Vector!(int, 2) d = a - b;
        assert(d[0] == 0);
        assert(d[1] == 1);
}

alias Vector!(float,3) Vector3D;
alias Vector!(float,2) Vector2D;

unittest {
        Vector3D x = new Vector3D(2,3,4);
        Vector3D y = x + x;
        assert(y[2] - 8 < 0.001);
}