Method decompose

core/math/Mat4.cpp:447–553

}

bool Mat4::decompose(Vec3* scale, Quaternion* rotation, Vec3* translation) const
{
    if (translation)
    {
        // Extract the translation.
        translation->x = m[12];
        translation->y = m[13];
        translation->z = m[14];
    }

    // Nothing left to do.
    if (scale == nullptr && rotation == nullptr)
        return true;

    // Extract the scale.
    // This is simply the length of each axis (row/column) in the matrix.
    Vec3 xaxis(m[0], m[1], m[2]);
    float scaleX = xaxis.length();

    Vec3 yaxis(m[4], m[5], m[6]);
    float scaleY = yaxis.length();

    Vec3 zaxis(m[8], m[9], m[10]);
    float scaleZ = zaxis.length();

    // Determine if we have a negative scale (true if determinant is less than zero).
    // In this case, we simply negate a single axis of the scale.
    float det = determinant();
    if (det < 0)
        scaleZ = -scaleZ;

    if (scale)
    {
        scale->x = scaleX;
        scale->y = scaleY;
        scale->z = scaleZ;
    }

    // Nothing left to do.
    if (rotation == nullptr)
        return true;

    // Scale too close to zero, can't decompose rotation.
    if (scaleX < MATH_TOLERANCE || scaleY < MATH_TOLERANCE || std::abs(scaleZ) < MATH_TOLERANCE)
        return false;

    float rn;

    // Factor the scale out of the matrix axes.
    rn = 1.0f / scaleX;
    xaxis.x *= rn;
    xaxis.y *= rn;
    xaxis.z *= rn;

    rn = 1.0f / scaleY;
    yaxis.x *= rn;
    yaxis.y *= rn;
    yaxis.z *= rn;