Matrix3D.java

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/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */



/** A fairly conventional 3D matrix object that can transform sets of
3D points and perform a variety of manipulations on the transform */
class Matrix3D {

    float xx, xy, xz, xo;
    float yx, yy, yz, yo;
    float zx, zy, zz, zo;
    static final double pi = 3.14159265;

    /** Create a new unit matrix */
    Matrix3D() {
        xx = 1.0f;
        yy = 1.0f;
        zz = 1.0f;
    }

    /** Scale by f in all dimensions */
    void scale(float f) {
        xx *= f;
        xy *= f;
        xz *= f;
        xo *= f;
        yx *= f;
        yy *= f;
        yz *= f;
        yo *= f;
        zx *= f;
        zy *= f;
        zz *= f;
        zo *= f;
    }

    /** Scale along each axis independently */
    void scale(float xf, float yf, float zf) {
        xx *= xf;
        xy *= xf;
        xz *= xf;
        xo *= xf;
        yx *= yf;
        yy *= yf;
        yz *= yf;
        yo *= yf;
        zx *= zf;
        zy *= zf;
        zz *= zf;
        zo *= zf;
    }

    /** Translate the origin */
    void translate(float x, float y, float z) {
        xo += x;
        yo += y;
        zo += z;
    }

    /** rotate theta degrees about the y axis */
    void yrot(double theta) {
        theta *= (pi / 180);
        double ct = Math.cos(theta);
        double st = Math.sin(theta);

        float Nxx = (float) (xx * ct + zx * st);
        float Nxy = (float) (xy * ct + zy * st);
        float Nxz = (float) (xz * ct + zz * st);
        float Nxo = (float) (xo * ct + zo * st);

        float Nzx = (float) (zx * ct - xx * st);
        float Nzy = (float) (zy * ct - xy * st);
        float Nzz = (float) (zz * ct - xz * st);
        float Nzo = (float) (zo * ct - xo * st);

        xo = Nxo;
        xx = Nxx;
        xy = Nxy;
        xz = Nxz;
        zo = Nzo;
        zx = Nzx;
        zy = Nzy;
        zz = Nzz;
    }

    /** rotate theta degrees about the x axis */
    void xrot(double theta) {
        theta *= (pi / 180);
        double ct = Math.cos(theta);
        double st = Math.sin(theta);

        float Nyx = (float) (yx * ct + zx * st);
        float Nyy = (float) (yy * ct + zy * st);
        float Nyz = (float) (yz * ct + zz * st);
        float Nyo = (float) (yo * ct + zo * st);

        float Nzx = (float) (zx * ct - yx * st);
        float Nzy = (float) (zy * ct - yy * st);
        float Nzz = (float) (zz * ct - yz * st);
        float Nzo = (float) (zo * ct - yo * st);

        yo = Nyo;
        yx = Nyx;
        yy = Nyy;
        yz = Nyz;
        zo = Nzo;
        zx = Nzx;
        zy = Nzy;
        zz = Nzz;
    }

    /** rotate theta degrees about the z axis */
    void zrot(double theta) {
        theta *= (pi / 180);
        double ct = Math.cos(theta);
        double st = Math.sin(theta);

        float Nyx = (float) (yx * ct + xx * st);
        float Nyy = (float) (yy * ct + xy * st);
        float Nyz = (float) (yz * ct + xz * st);
        float Nyo = (float) (yo * ct + xo * st);

        float Nxx = (float) (xx * ct - yx * st);
        float Nxy = (float) (xy * ct - yy * st);
        float Nxz = (float) (xz * ct - yz * st);
        float Nxo = (float) (xo * ct - yo * st);

        yo = Nyo;
        yx = Nyx;
        yy = Nyy;
        yz = Nyz;
        xo = Nxo;
        xx = Nxx;
        xy = Nxy;
        xz = Nxz;
    }

    /** Multiply this matrix by a second: M = M*R */
    void mult(Matrix3D rhs) {
        float lxx = xx * rhs.xx + yx * rhs.xy + zx * rhs.xz;
        float lxy = xy * rhs.xx + yy * rhs.xy + zy * rhs.xz;
        float lxz = xz * rhs.xx + yz * rhs.xy + zz * rhs.xz;
        float lxo = xo * rhs.xx + yo * rhs.xy + zo * rhs.xz + rhs.xo;

        float lyx = xx * rhs.yx + yx * rhs.yy + zx * rhs.yz;
        float lyy = xy * rhs.yx + yy * rhs.yy + zy * rhs.yz;
        float lyz = xz * rhs.yx + yz * rhs.yy + zz * rhs.yz;
        float lyo = xo * rhs.yx + yo * rhs.yy + zo * rhs.yz + rhs.yo;

        float lzx = xx * rhs.zx + yx * rhs.zy + zx * rhs.zz;
        float lzy = xy * rhs.zx + yy * rhs.zy + zy * rhs.zz;
        float lzz = xz * rhs.zx + yz * rhs.zy + zz * rhs.zz;
        float lzo = xo * rhs.zx + yo * rhs.zy + zo * rhs.zz + rhs.zo;

        xx = lxx;
        xy = lxy;
        xz = lxz;
        xo = lxo;

        yx = lyx;
        yy = lyy;
        yz = lyz;
        yo = lyo;

        zx = lzx;
        zy = lzy;
        zz = lzz;
        zo = lzo;
    }

    /** Reinitialize to the unit matrix */
    void unit() {
        xo = 0;
        xx = 1;
        xy = 0;
        xz = 0;
        yo = 0;
        yx = 0;
        yy = 1;
        yz = 0;
        zo = 0;
        zx = 0;
        zy = 0;
        zz = 1;
    }

    /** Transform nvert points from v into tv.  v contains the input
    coordinates in floating point.  Three successive entries in
    the array constitute a point.  tv ends up holding the transformed
    points as integers; three successive entries per point */
    void transform(float v[], int tv[], int nvert) {
        float lxx = xx, lxy = xy, lxz = xz, lxo = xo;
        float lyx = yx, lyy = yy, lyz = yz, lyo = yo;
        float lzx = zx, lzy = zy, lzz = zz, lzo = zo;
        for (int i = nvert * 3; (i -= 3) >= 0;) {
            float x = v[i];
            float y = v[i + 1];
            float z = v[i + 2];
            tv[i] = (int) (x * lxx + y * lxy + z * lxz + lxo);
            tv[i + 1] = (int) (x * lyx + y * lyy + z * lyz + lyo);
            tv[i + 2] = (int) (x * lzx + y * lzy + z * lzz + lzo);
        }
    }

    @Override
    public String toString() {
        return ("[" + xo + "," + xx + "," + xy + "," + xz + ";"
                + yo + "," + yx + "," + yy + "," + yz + ";"
                + zo + "," + zx + "," + zy + "," + zz + "]");
    }
}