{

public:

MatrixStack(size_t startSize = 16) noexcept(false) :

m_stackSize(0),

m_current(0),

m_stack(nullptr)

{

assert(startSize > 0);

Allocate(startSize);

LoadIdentity();

}

MatrixStack(MatrixStack&&) = default;

MatrixStack& operator= (MatrixStack&&) = default;

MatrixStack(MatrixStack const&) = delete;

MatrixStack& operator= (MatrixStack const&) = delete;

const XMMATRIX XM_CALLCONV Top() const noexcept { return m_stack[m_current]; }

const XMMATRIX* GetTop() const noexcept { return &m_stack[m_current]; }

size_t Size() const noexcept { return (m_current + 1); }

void Pop()

{

if (m_current > 0)

{

--m_current;

}

}

void Push()

{

++m_current;

if (m_current >= m_stackSize)

{

Allocate(m_stackSize * 2);

}

// Replicate the original top of the matrix stack.

m_stack[m_current] = m_stack[m_current - 1];

}

// Loads identity into the top of the matrix stack.

void LoadIdentity() noexcept

{

m_stack[m_current] = XMMatrixIdentity();

}

// Load a matrix into the top of the matrix stack.

void XM_CALLCONV LoadMatrix(FXMMATRIX matrix) noexcept

{

m_stack[m_current] = matrix;

}

// Multiply a matrix by the top of the stack, store result in top.

void XM_CALLCONV MultiplyMatrix(FXMMATRIX matrix) noexcept

{

m_stack[m_current] = XMMatrixMultiply(m_stack[m_current], matrix);

}

// Pre-multiplies a matrix by the top of the stack, store result in top.

void XM_CALLCONV MultiplyMatrixLocal(FXMMATRIX matrix) noexcept

{

m_stack[m_current] = XMMatrixMultiply(matrix, m_stack[m_current]);

}

// Add a rotation about X to stack top.

void XM_CALLCONV RotateX(float angle) noexcept

{

XMMATRIX mat = XMMatrixRotationX(angle);

m_stack[m_current] = XMMatrixMultiply(m_stack[m_current], mat);

}

void XM_CALLCONV RotateXLocal(float angle) noexcept

{

XMMATRIX mat = XMMatrixRotationX(angle);

m_stack[m_current] = XMMatrixMultiply(mat, m_stack[m_current]);

}

// Add a rotation about Y to stack top.

void XM_CALLCONV RotateY(float angle) noexcept

{

XMMATRIX mat = XMMatrixRotationY(angle);

m_stack[m_current] = XMMatrixMultiply(m_stack[m_current], mat);

}

void XM_CALLCONV RotateYLocal(float angle) noexcept

{

XMMATRIX mat = XMMatrixRotationY(angle);

m_stack[m_current] = XMMatrixMultiply(mat, m_stack[m_current]);

}

// Add a rotation about Z to stack top.

void XM_CALLCONV RotateZ(float angle) noexcept

{

XMMATRIX mat = XMMatrixRotationZ(angle);

m_stack[m_current] = XMMatrixMultiply(m_stack[m_current], mat);

}

void XM_CALLCONV RotateZLocal(float angle) noexcept

{

XMMATRIX mat = XMMatrixRotationZ(angle);

m_stack[m_current] = XMMatrixMultiply(mat, m_stack[m_current]);

}

// Add a rotation around an axis to stack top.

void XM_CALLCONV RotateAxis(FXMVECTOR axis, float angle) noexcept

{

XMMATRIX mat = XMMatrixRotationAxis(axis, angle);

m_stack[m_current] = XMMatrixMultiply(m_stack[m_current], mat);

}

void XM_CALLCONV RotateAxisLocal(FXMVECTOR axis, float angle) noexcept

{

XMMATRIX mat = XMMatrixRotationAxis(axis, angle);

m_stack[m_current] = XMMatrixMultiply(mat, m_stack[m_current]);

}

// Add a rotation by roll/pitch/yaw to the stack top.

void RotateRollPitchYaw(float pitch, float yaw, float roll) noexcept

{

XMMATRIX mat = XMMatrixRotationRollPitchYaw(pitch, yaw, roll);

m_stack[m_current] = XMMatrixMultiply(m_stack[m_current], mat);

}

void RotateRollPitchYawLocal(float pitch, float yaw, float roll) noexcept

{

XMMATRIX mat = XMMatrixRotationRollPitchYaw(pitch, yaw, roll);

m_stack[m_current] = XMMatrixMultiply(mat, m_stack[m_current]);

}

// Add a rotation by a quaternion stack top.

void XM_CALLCONV RotateByQuaternion(FXMVECTOR quat) noexcept

{

XMMATRIX mat = XMMatrixRotationQuaternion(quat);

m_stack[m_current] = XMMatrixMultiply(m_stack[m_current], mat);

}

void XM_CALLCONV RotateByQuaternionLocal(FXMVECTOR quat) noexcept

{

XMMATRIX mat = XMMatrixRotationQuaternion(quat);

m_stack[m_current] = XMMatrixMultiply(mat, m_stack[m_current]);

}

// Add a scale to the stack top.

void Scale(float x, float y, float z) noexcept

{

XMMATRIX mat = XMMatrixScaling(x, y, z);

m_stack[m_current] = XMMatrixMultiply(m_stack[m_current], mat);

}

void ScaleLocal(float x, float y, float z) noexcept

{

XMMATRIX mat = XMMatrixScaling(x, y, z);

m_stack[m_current] = XMMatrixMultiply(mat, m_stack[m_current]);

}

// Add a translation to the stack top.

void Translate(float x, float y, float z) noexcept

{

XMMATRIX mat = XMMatrixTranslation(x, y, z);

m_stack[m_current] = XMMatrixMultiply(m_stack[m_current], mat);

}

void TranslateLocal(float x, float y, float z) noexcept

{

XMMATRIX mat = XMMatrixTranslation(x, y, z);

m_stack[m_current] = XMMatrixMultiply(mat, m_stack[m_current]);

}

private:

struct matrix_deleter

{

void operator()(void* p) noexcept

{

#ifdef _WIN32

_aligned_free(p);

#else

free(p);

#endif

}

};

void Allocate(size_t newSize)

{

#ifdef _WIN32

void* ptr = _aligned_malloc(newSize * sizeof(XMMATRIX), 16);

#else

// This C++17 Standard Library function is currently NOT

// implemented for the Microsoft Standard C++ Library.

void* ptr = aligned_alloc(16, newSize * sizeof(XMMATRIX));

#endif

if (!ptr)

throw std::bad_alloc();

if (m_stack)

{

assert(newSize >= m_stackSize);

memcpy(ptr, m_stack.get(), sizeof(XMMATRIX) * m_stackSize);

}

m_stack.reset(reinterpret_cast<XMMATRIX*>(ptr));

m_stackSize = newSize;

}

size_t m_stackSize;

size_t m_current;

std::unique_ptr<XMMATRIX[], matrix_deleter> m_stack;