view matrix resets itself.

Sun, 22 Nov 2009 10:03:06 -0800

I have written a Camera class that utilises direct input to rotate view matrix. For some reason, the view rotates when I move the mouse but then suddenly snaps back to the original rotation. Any idea why?

Camera.cpp

#include "Camera.h"

Camera::Camera(D3DXVECTOR3 m_pos, LPDIRECT3DDEVICE9 m_pdxDevice, HINSTANCE hInst, HWND gameWindow)
{
	_position = m_pos;
	_look = D3DXVECTOR3(0,0,0);
	_up = D3DXVECTOR3(0,1,0);

	D3DXMatrixPerspectiveFovLH(&_projection, D3DX_PI/4, 500/500, 1, 500);
	m_pdxDevice->SetTransform(D3DTS_PROJECTION, &_projection);

	//----INITIALISE INPUT---------
	DirectInput8Create(hInst, DIRECTINPUT_VERSION, IID_IDirectInput8, (void**)&pDirectInput, NULL);
	pDirectInput->CreateDevice(GUID_SysKeyboard, &pKeyboard, NULL);
	pKeyboard->SetDataFormat(&c_dfDIKeyboard);
	pKeyboard->SetCooperativeLevel(gameWindow, DISCL_FOREGROUND | DISCL_NONEXCLUSIVE);
	pKeyboard->Acquire();

	pDirectInput->CreateDevice(GUID_SysMouse, &pMouse, NULL);
	pMouse->SetDataFormat(&c_dfDIMouse);
	pMouse->SetCooperativeLevel(gameWindow, DISCL_FOREGROUND | DISCL_NONEXCLUSIVE);
	pMouse->Acquire();
}

void Camera::ProcessKeyboard()
{
	char KeyboardState[256];

	pKeyboard->GetDeviceState(sizeof(KeyboardState),(LPVOID)&Key
boardState);
	if(KEYDOWN(KeyboardState, DIK_RIGHT)) { _position.x++; _look.x++; }
	if(KEYDOWN(KeyboardState, DIK_LEFT)) { _position.x--; _look.x--; }
	if(KEYDOWN(KeyboardState, DIK_UP)) { _position.z++; _look.z++; }
	if(KEYDOWN(KeyboardState, DIK_DOWN)) { _position.z--; _look.z--; }
}

void Camera::ProcessMouse()
{
	DIMOUSESTATE MouseState;
	pMouse->GetDeviceState(sizeof(MouseState),(LPVOID)&MouseS
tate);

	_yaw = MouseState.lX / 80.0f;
	_pitch = MouseState.lY / 80.0f;
}

void Camera::Update(LPDIRECT3DDEVICE9 m_pdxDevice)
{
	ProcessKeyboard(); ProcessMouse();

	D3DXMatrixLookAtLH(&_view, &_position, &_look, &_up);
	m_pdxDevice->SetTransform(D3DTS_VIEW, &_view);

	_up=D3DXVECTOR3(0,1,0);
	_look=D3DXVECTOR3(0,0,1);
	_right=D3DXVECTOR3(1,0,0);

	D3DXMATRIX yawMatrix;
	D3DXMatrixRotationAxis(&yawMatrix, &_up, _yaw);
	// To apply yaw we rotate the m_look & m_right vectors about the m_up vector (using our yaw matrix)
	D3DXVec3TransformCoord(&_look, &_look, &yawMatrix); 
	D3DXVec3TransformCoord(&_right, &_right, &yawMatrix); 

	// Pitch is rotation around the x axis (m_right)
	// Create a matrix that can carry out this rotation
	D3DXMATRIX pitchMatrix;
	D3DXMatrixRotationAxis(&pitchMatrix, &_right, _pitch);
	// To apply pitch we rotate the m_look and m_up vectors about the m_right vector (using our pitch matrix)
	D3DXVec3TransformCoord(&_look, &_look, &pitchMatrix); 
	D3DXVec3TransformCoord(&_up, &_up, &pitchMatrix); 
		
	// Roll is rotation around the z axis (m_look)
	// Create a matrix that can carry out this rotation
	D3DXMATRIX rollMatrix;
	D3DXMatrixRotationAxis(&rollMatrix, &_look, _roll);
	// To apply roll we rotate up and right about the look vector (using our roll matrix)
	// Note: roll only really applies for things like aircraft unless you are implementing lean
	D3DXVec3TransformCoord(&_right, &_right, &rollMatrix); 
	D3DXVec3TransformCoord(&_up, &_up, &rollMatrix); 

	// Build the view matrix from the transformed camera axis
	D3DXMATRIX *m_view = &_view;
	D3DXMatrixIdentity(m_view);

	m_view->_11 = _right.x; m_view->_12 = _up.x; m_view->_13 = _look.x;
	m_view->_21 = _right.y; m_view->_22 = _up.y; m_view->_23 = _look.y;
	m_view->_31 = _right.z; m_view->_32 = _up.z; m_view->_33 = _look.z;
	
	m_view->_41 = - D3DXVec3Dot( &_position,&_right); 
	m_view->_42 = - D3DXVec3Dot( &_position,&_up);
	m_view->_43 = - D3DXVec3Dot( &_position,&_look);
}

void Camera::SetPosition(D3DXVECTOR3 m_pos)
{
	_position = m_pos;
}

Camera::~Camera(void)
{
}

Camera.h

#include<d3d9.h>
#include<d3dx9.h>
#include<dinput.h>
#define KEYDOWN(name, key) (name[key] & 0x80)
#pragma once

class Camera
{
public:
	Camera(D3DXVECTOR3 position, LPDIRECT3DDEVICE9 device, HINSTANCE hInst, HWND gameWindow);
	void Update(LPDIRECT3DDEVICE9 m_pdxDevice);

	void SetPosition(D3DXVECTOR3 position);

	float GetYaw() const {return _yaw;}
	float GetPitch() const {return _pitch;}
	float GetRoll() const {return _roll;}
	D3DXVECTOR3 GetPosition() const {return _position;}	
	D3DXMATRIX GetViewMatrix() const {return _view;}

	// Move operations
	void MoveForward(float amount);
	void MoveRight(float amount);
	void MoveUp(float amount);

	// Rotations
	void Yaw(float amount); // rotate around x axis
	void Pitch(float amount); // rotate around x axis
	void Roll(float amount); // rotate around z axis	
	
	~Camera(void);

private:
	D3DXVECTOR3 _position;
	D3DXVECTOR3 _up, _look, _right;
	float _yaw, _pitch, _roll;

	D3DXMATRIX _view;
	D3DXMATRIX _projection;	
	LPDIRECTINPUT8 pDirectInput; 
	LPDIRECTINPUTDEVICE8 pKeyboard;
	LPDIRECTINPUTDEVICE8 pMouse;

	void ProcessKeyboard(void);
	void ProcessMouse(void);

};

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view matrix resets itself.