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


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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

PR

UL

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

+x

+z

O

AB

C

D

+x

+z

O

AB

C

D

+x

+z

O

AD

B

C

< View Space Transformation >

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

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 =−

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Part 2: Rotation (1)

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

[ ] [ ]001

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121110

020100

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Part 2: Rotation (2)

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

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⎡=

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zzz

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ABB 1

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Combining Both Parts

View transformation matrix V:

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⋅−⋅−⋅−

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1

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0

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0

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0001

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TAV

zyx

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ppp

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ppp


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

ex)

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

);

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

);

A

Y

Z

X

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



Pitch, yaw, and roll

PR

UL

PR

L

U

Pitch

PR

UL

PL

U

R

Yaw

PR

UL

PU

RL

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

sL

P’=P+sL

tR P’=P+tR

rU

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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