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// This code is in the public domain -- Ignacio Castaño <castano@gmail.com>
#pragma once
#ifndef NV_MATH_BASIS_H
#define NV_MATH_BASIS_H
#include "nvmath.h"
#include "Vector.inl"
#include "Matrix.h"
namespace nv
{
/// Basis class to compute tangent space basis, ortogonalizations and to
/// transform vectors from one space to another.
class Basis
{
public:
/// Create a null basis.
Basis() : tangent(0, 0, 0), bitangent(0, 0, 0), normal(0, 0, 0) {}
/// Create a basis given three vectors.
Basis(Vector3::Arg n, Vector3::Arg t, Vector3::Arg b) : tangent(t), bitangent(b), normal(n) {}
/// Create a basis with the given tangent vectors and the handness.
Basis(Vector3::Arg n, Vector3::Arg t, float sign)
{
build(n, t, sign);
}
NVMATH_API void normalize(float epsilon = NV_EPSILON);
NVMATH_API void orthonormalize(float epsilon = NV_EPSILON);
NVMATH_API void robustOrthonormalize(float epsilon = NV_EPSILON);
NVMATH_API void buildFrameForDirection(Vector3::Arg d, float angle = 0);
/// Calculate the determinant [ F G N ] to obtain the handness of the basis.
float handness() const
{
return determinant() > 0.0f ? 1.0f : -1.0f;
}
/// Build a basis from 2 vectors and a handness flag.
void build(Vector3::Arg n, Vector3::Arg t, float sign)
{
normal = n;
tangent = t;
bitangent = sign * cross(t, n);
}
/// Compute the determinant of this basis.
float determinant() const
{
return
tangent.x * bitangent.y * normal.z - tangent.z * bitangent.y * normal.x +
tangent.y * bitangent.z * normal.x - tangent.y * bitangent.x * normal.z +
tangent.z * bitangent.x * normal.y - tangent.x * bitangent.z * normal.y;
}
bool isValid() const;
// Get transform matrix for this basis.
NVMATH_API Matrix matrix() const;
// Transform by this basis. (From this basis to object space).
NVMATH_API Vector3 transform(Vector3::Arg v) const;
// Transform by the transpose. (From object space to this basis).
NVMATH_API Vector3 transformT(Vector3::Arg v);
// Transform by the inverse. (From object space to this basis).
NVMATH_API Vector3 transformI(Vector3::Arg v) const;
Vector3 tangent;
Vector3 bitangent;
Vector3 normal;
};
} // nv namespace
#endif // NV_MATH_BASIS_H
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