Lecture Computer graphics: Lecture 26 - Fasih ur Rehman

In this chapter, you learn what is input and output devices. The keyboard is presented and different keyboard types are described. You are introduced to various pointing devices, such as the mouse, trackball, touchpad, pointing stick, joystick, touchscreen, and pen input. Scanners and reading devices, including optical scanners, optical readers, magnetic ink character recognition readers, and data collection devices are explained,...

Computer Graphics

Lecture 26 Fasih ur Rehman

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Matrix Multiplication

void matrixMul(float P[1][3],float T[3][3])

{

int i,j,k; //Initialize Matrix P1 with Zero

for(i=0;i<3;i++)

P1[0][i]=0; /*Mutiply T with P and store the result in P1 */

for(k=0;k<1;k++)

for(i=0;i<3;i++)

[i]+=P[k][j]*T[j][i];

}

Matrix Identity

void matrixIdentity(float T[3][3])

{

int i,j;

/* Make matrix T as Identity Matrix by Storing 1 in the left diagonal positions of Matrix T and store 0 in other positions */

for(i=0;i<3;i++) {

for(j=0;j<3;j++) {

if(i==j)

T[i][j]=1;

else

T[i][j]=0;

} }

}

void translate_point(int x,int y,int tx,int ty)

//Translate a point by translation factors tx,ty {

float T[3][3];

matrixIdentity(T);

T[2][0]=tx;

T[2][1]=ty;

P[0][0]=x;

P[0][1]=y;

P[0][2]=1;

matrixMul(P,T);

}

void rotate_point(int x,int y,float angle) // Rotate a point by given angle

{

float R[3][3];

float radian;

radian=(3.141/180)*angle;

matrixIdentity(R);

R[0][0]=cos(radian);

R[1][0]=-1*sin(radian);

R[2][0]=0;

R[0][1]=sin(radian);

R[1][1]=cos(radian);

R[2][1]=0;

P[0][0]=x;

P[0][1]=y;

P[0][2]=1;

matrixMul(P,R);

}

void scale_point(int x,int y,float sx,float sy)

/* Scale a point by scaling factors sx,sy and with respect to some fixed point */

{

float S[3][3];

matrixIdentity(S);

S[0][0]=sx;

S[2][0]=0;

S[1][1]=sy;

S[2][1]=0;

P[0][0]=x;

P[0][1]=y;

P[0][2]=1;

matrixMul(P,S);

}

void reflect_point_X(int x,int y) {

float R[3][3];

matrixIdentity(R);

R[1][1]=-1;

P[0][0]=x;

P[0][1]=y;

P[0][2]=1;

matrixMul(P,R);

}

void shear_point_Y(int x,int y,float shy) {

float R[3][3];

matrixIdentity(R);

R[0][1]=shy;

P[0][0]=x;

P[0][1]=y;

P[0][2]=1;

matrixMul(P,R);

}

Summary

Edition by Peter Shirley and Steve

Marschner

Top-down Approach with OpenGL (Sixth

Edition) by Edward Angel

rame_cpp.html