Building a Flexible Camera Class - hallym.ac.krgraphics.hallym.ac.kr/teach/2005/gp2/src/01camera.pdf · Sun-Jeong Kim sunkim/teach/2005/gp2sunkim/teach/2005/gp1 File ÆNew Sun-Jeong

Game Programming

Sun-Jeong Kim http://www.hallym.ac.kr/~sunkim/teach/2005/gp2

Building a Flexible Camera Class

September 01, 2005

Sun-Jeong Kim http://www.hallym.ac.kr/~sunkim/teach/2005/gp1http://www.hallym.ac.kr/~sunkim/teach/2005/gp2

DirectX SDK & Sample Codes

File New

Copy Sample Files

Project Add To Project

FileView

Project Settings

Tool Options

Directories

Sample: Camera

Control Keys

W / S – walk forward / backward

A / D – Strafe left / right

R / F – Fly up / down

Up / Down arrow keys – Pitch

Left / Right arrow keys – Yaw

N / M – Roll

Analysis of Sample: Camera

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

InitD3D();EnterMsgLoop();DrawBasicScene();

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

WinMain( )

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

Creating the Main Window

Initializing Direct3D (Step 1)

Initializing Direct3D (Step 2,3)

Initializing Direct3D (Step 4)

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

Setup ( ) – Projection

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

Creating the Buffers

Accessing the Buffers

Setting Rendering States

Rendering Background

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

EnterMsgLoop ( )

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

WndProc ( )

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

Handling Keyboard Events

Camera & Rendering Scene

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

Cleanup ( )

cameraApp.cpp

d3dUtility.cpp

d3dUtility.h

InitD3D();

Setup();

EnterMsgLoop();

Cleanup();

WndProc();

Display();

WinMain();

WndProc();

Setup();

Cleanup();

Display();

camera.h

camera.cpp

Objective

To learn how to implement a flexible Cameraclass

suitable for light simulators games played from first-person perspective

D3DXMatrixLookAtLH( ) function

[+] positioning and aiming a camera in a fixed position

[−] moving camera that reacts to user input

Motivation

Camera Design (1)

Four camera vectorsposition and orientation of the camera

right, up, look, and position vectors

(R, U, L): orientation vectors

orthonormal vectors

orthogonal matrix

inverse == transpose

World Space

P = Position vectorR = Right vectorU = Up vectorL = Look vector

Camera Design (2)

Six operations – six degrees of freedomrotate around the right vector (pitch)

rotate around the up vector (yaw)

rotate around the look vector (roll)

strafe along the right vector

fly along the up vector

move along look vector

Camera Design (3)

class Camera{public:

enum CameraType { LANDOBJECT, AIRCRAFT };

Camera();Camera(CameraType cameraType);~Camera();

void strafe(float units); // left/rightvoid fly(float units); // up/downvoid walk(float units); // forward/backward

void pitch(float angle); // rotate on right vectorvoid yaw(float angle); // rotate on up vectorvoid roll(float angle); // rotate on look vector

void getViewMatrix(D3DXMATRIX* V); void setCameraType(CameraType cameraType); void getPosition(D3DXVECTOR3* pos); void setPosition(D3DXVECTOR3* pos);

void getRight(D3DXVECTOR3* right);void getUp(D3DXVECTOR3* up);void getLook(D3DXVECTOR3* look);

private:CameraType _cameraType;D3DXVECTOR3 _right;D3DXVECTOR3 _up;D3DXVECTOR3 _look;D3DXVECTOR3 _pos;

Implementation Details (1)

Computing the view matrix

p = (px, py, pz) : position vectorr = (rx, ry, rz) : right vectoru = (ux, uy, uz) : up vectord = (dx, dy, dz) : look vector

< View Space Transformation >

pV = (0, 0, 0) : originrV = (1, 0, 0) : x-axisuV = (0, 1, 0) : y-axisdV = (0, 0, 1) : z-axis

Part 1: Translation

Taking p to the origin

0px =−

⎥⎥⎥⎥⎥

⎢⎢⎢⎢⎢

−−−

zyx ppp

( ) ( ) ( )000=− zyx pppzyx

pzpypx

−−−=⎥⎥⎥⎥⎥

⎢⎢⎢⎢⎢

−−−

Part 2: Rotation (1)

Aligning r, u, d camera vectors with world’s axes

[ ] [ ]001

222120

121110

020100

=⎥⎥⎥

⎢⎢⎢

rrr zyxrA

[ ] [ ]010

222120

121110

020100

=⎥⎥⎥

⎢⎢⎢

uuu zyxuA

[ ] [ ]100

222120

121110

020100

=⎥⎥⎥

⎢⎢⎢

ddd zyxdA

Part 2: Rotation (2)

Aligning r, u, d camera vectors with world’s axes

⎥⎥⎥

⎢⎢⎢

⎥⎥⎥

⎢⎢⎢

⎥⎥⎥

⎢⎢⎢

222120

121110

020100

[ ] [ ]001

222120

121110

020100

=⎥⎥⎥

⎢⎢⎢

rrr zyxrA

[ ] [ ]010

222120

121110

020100

=⎥⎥⎥

⎢⎢⎢

uuu zyxuA

[ ] [ ]100

222120

121110

020100

=⎥⎥⎥

⎢⎢⎢

ddd zyxdA

⎥⎥⎥

⎢⎢⎢

⎡===−

Combining Both Parts

View transformation matrix V:

⎥⎥⎥⎥⎥

⎢⎢⎢⎢⎢

⋅−⋅−⋅−

⎥⎥⎥⎥

⎢⎢⎢⎢

⎥⎥⎥⎥⎥

⎢⎢⎢⎢⎢

−−−

Camera :: getViewMatrix ( )

void Camera::getViewMatrix(D3DXMATRIX* V){

// Keep camera's axes orthogonal to each otherD3DXVec3Normalize(&_look, &_look);

D3DXVec3Cross(&_up, &_look, &_right);D3DXVec3Normalize(&_up, &_up);

D3DXVec3Cross(&_right, &_up, &_look);D3DXVec3Normalize(&_right, &_right);

// Build the view matrix:float x = -D3DXVec3Dot(&_right, &_pos);float y = -D3DXVec3Dot(&_up, &_pos);float z = -D3DXVec3Dot(&_look, &_pos);

(*V)(0, 0) = _right.x; (*V)(0, 1) = _up.x; (*V)(0, 2) = _look.x; (*V)(0, 3) = 0.0f;

(*V)(1, 0) = _right.y; (*V)(1, 1) = _up.y; (*V)(1, 2) = _look.y; (*V)(1, 3) = 0.0f;

(*V)(2, 0) = _right.z; (*V)(2, 1) = _up.z; (*V)(2, 2) = _look.z; (*V)(2, 3) = 0.0f;

(*V)(3, 0) = x; (*V)(3, 1) = y; (*V)(3, 2) = z; (*V)(3, 3) = 1.0f;

Rotation about an arbitrary axis

D3DXMATRIX &D3DXMatrixRotationAxis (D3DXMATRIX *pOut,CONST D3DXVECTOR *pV,FLOAT Angle

D3DXMATRIX R;D3DXVECTOR3 axis(0.707f, 0.707f, 0.0f);D3DXMatrixRotationAxis(&R, &axis, D3DX_PI/2.0f);

Pitch, yaw, and roll

Camera :: pitch ( ) and yaw ( )

void Camera::pitch(float angle){

D3DXMATRIX T;D3DXMatrixRotationAxis(&T, &_right, angle);

// rotate _up and _look around _right vectorD3DXVec3TransformCoord(&_up,&_up, &T);D3DXVec3TransformCoord(&_look,&_look, &T);

void Camera::yaw(float angle){

D3DXMATRIX T;

// rotate around world y (0, 1, 0) always for land objectif( _cameraType == LANDOBJECT )

D3DXMatrixRotationY(&T, angle);

// rotate around own up vector for aircraftif( _cameraType == AIRCRAFT )

D3DXMatrixRotationAxis(&T, &_up, angle);

// rotate _right and _look around _up or y-axisD3DXVec3TransformCoord(&_right,&_right, &T);D3DXVec3TransformCoord(&_look,&_look, &T);

Camera :: roll ( )

void Camera::roll(float angle){

// only roll for aircraft typeif( _cameraType == AIRCRAFT ){

D3DXMATRIX T;D3DXMatrixRotationAxis(&T, &_look, angle);

// rotate _up and _right around _look vectorD3DXVec3TransformCoord(&_right,&_right, &T);D3DXVec3TransformCoord(&_up,&_up, &T);

Walking, strafing, and flying

P’=P+sL

tR P’=P+tR

P’=P+rU

Camera :: walk, strafe, fly ( )

void Camera::walk(float units){

// move only on xz plane for land objectif( _cameraType == LANDOBJECT )

_pos += D3DXVECTOR3(_look.x, 0.0f, _look.z) * units;

if( _cameraType == AIRCRAFT )_pos += _look * units;

void Camera::strafe(float units){

// move only on xz plane for land objectif( _cameraType == LANDOBJECT )

_pos += D3DXVECTOR3(_right.x, 0.0f, _right.z) * units;

if( _cameraType == AIRCRAFT )_pos += _right * units;

void Camera::fly(float units){

// move only on y-axis for land objectif( _cameraType == LANDOBJECT )

_pos.y += units;

if( _cameraType == AIRCRAFT )_pos += _up * units;

Sample: Camera

Control Keys

W / S – walk forward / backward

A / D – Strafe left / right

R / F – Fly up / down

Up / Down arrow keys – Pitch

Left / Right arrow keys – Yaw

N / M – Roll

Creation of a Camera Object

Moving of a Camera

Getting of a View Matrix

Exercise

Create a Camera object for an airplane

Change the view: airplane whole view

whole view airplane

Building a Flexible Camera Class - hallym.ac.krgraphics.hallym.ac.kr/teach/2005/gp2/src/01camera.pdf · Sun-Jeong Kim sunkim/teach/2005/gp2sunkim/teach/2005/gp1 File ÆNew Sun-Jeong

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