Implementation of Reflection Transformation

SOURCE CODE :

//programed by Paras Wadher
MCA
Nagpur university

/* A C++ program to illustrate the implementation of Reflection Transformation
about x-axix, y-axis and w.r.t origin. */

# include <iostream.h>
# include <graphics.h>
# include <conio.h>
# include <math.h>

//———————– Function Prototypes ————————-//

void show_screen( );

void apply_reflection_along_x_axis(const int,int []);
void apply_reflection_along_y_axis(const int,int []);
void apply_reflection_wrt_origin(const int,int []);
void multiply_matrices(const int[3],const int[3][3],int[3]);

void Polygon(const int,const int []);
void Line(const int,const int,const int,const int);

//—————————— main( ) ——————————//

int main( )
{
int driver=VGA;
int mode=VGAHI;

initgraph(&driver,&mode,”..\\Bgi”);

show_screen( );

setcolor(15);
Line(320,100,320,400);

Line(315,105,320,100);
Line(320,100,325,105);

Line(315,395,320,400);
Line(320,400,325,395);

Line(150,240,500,240);

Line(150,240,155,235);
Line(150,240,155,245);

Line(500,240,495,235);
Line(500,240,495,245);

settextstyle(2,0,4);
outtextxy(305,85,”y-axis”);
outtextxy(305,402,”y’-axis”);

outtextxy(505,233,”x-axis”);
outtextxy(105,233,”x’-axis”);

outtextxy(380,100,”Original Object”);
outtextxy(380,385,”Reflection along x-axis”);
outtextxy(135,100,”Reflection along y-axis”);
outtextxy(135,385,”Reflection w.r.t origin”);

int polygon_points[8]={ 350,200, 380,150, 470,200, 350,200 };
int x_polygon[8]={ 350,200, 380,150, 470,200, 350,200 };
int y_polygon[8]={ 350,200, 380,150, 470,200, 350,200 };
int origin_polygon[8]={ 350,200, 380,150, 470,200, 350,200 };

setcolor(15);
Polygon(4,polygon_points);

apply_reflection_along_x_axis(4,x_polygon);

setcolor(12);
Polygon(4,x_polygon);

apply_reflection_along_y_axis(4,y_polygon);

setcolor(14);
Polygon(4,y_polygon);

apply_reflection_wrt_origin(4,origin_polygon);

setcolor(10);
Polygon(4,origin_polygon);

getch( );
return 0;
}

//———————— Funcion Definitions ————————//

//—————— apply_reflection_along_x_axis( ) —————–//

void apply_reflection_along_x_axis(const int n,int coordinates[])
{
for(int count=0;count<n;count++)
{
int matrix_a[3]={coordinates[(count*2)],
coordinates[((count*2)+1)],1};
int matrix_b[3][3]={ {1,0,0} , {0,-1,0} ,{ 0,0,1} };
int matrix_c[3]={0};

multiply_matrices(matrix_a,matrix_b,matrix_c);

coordinates[(count*2)]=matrix_c[0];
coordinates[((count*2)+1)]=(480+matrix_c[1]);
}
}

//—————— apply_reflection_along_y_axis( ) —————–//

void apply_reflection_along_y_axis(const int n,int coordinates[])
{
for(int count=0;count<n;count++)
{
int matrix_a[3]={coordinates[(count*2)],
coordinates[((count*2)+1)],1};
int matrix_b[3][3]={ {-1,0,0} , {0,1,0} ,{ 0,0,1} };
int matrix_c[3]={0};

multiply_matrices(matrix_a,matrix_b,matrix_c);

coordinates[(count*2)]=(640+matrix_c[0]);
coordinates[((count*2)+1)]=matrix_c[1];
}
}

//—————— apply_reflection_wrt_origin( ) ——————-//

void apply_reflection_wrt_origin(const int n,int coordinates[])
{
for(int count=0;count<n;count++)
{
int matrix_a[3]={coordinates[(count*2)],
coordinates[((count*2)+1)],1};
int matrix_b[3][3]={ {-1,0,0} , {0,-1,0} ,{ 0,0,1} };
int matrix_c[3]={0};

multiply_matrices(matrix_a,matrix_b,matrix_c);

coordinates[(count*2)]=(640+matrix_c[0]);
coordinates[((count*2)+1)]=(480+matrix_c[1]);
}
}

//———————- multiply_matrices( ) ————————//

void multiply_matrices(const int matrix_1[3],
const int matrix_2[3][3],int matrix_3[3])
{
for(int count_1=0;count_1<3;count_1++)
{
for(int count_2=0;count_2<3;count_2++)
matrix_3[count_1]+=
(matrix_1[count_2]*matrix_2[count_2][count_1]);
}
}

//—————————– Polygon( ) —————————-//

void Polygon(const int n,const int coordinates[])
{
if(n>=2)
{
Line(coordinates[0],coordinates[1],
coordinates[2],coordinates[3]);

for(int count=1;count<(n-1);count++)
Line(coordinates[(count*2)],coordinates[((count*2)+1)],
coordinates[((count+1)*2)],
coordinates[(((count+1)*2)+1)]);
}
}

//——————————- Line( ) —————————–//

void Line(const int x_1,const int y_1,const int x_2,const int y_2)
{
int color=getcolor( );

int x1=x_1;
int y1=y_1;

int x2=x_2;
int y2=y_2;

if(x_1>x_2)
{
x1=x_2;
y1=y_2;

x2=x_1;
y2=y_1;
}

int dx=abs(x2-x1);
int dy=abs(y2-y1);
int inc_dec=((y2>=y1)?1:-1);

if(dx>dy)
{
int two_dy=(2*dy);
int two_dy_dx=(2*(dy-dx));
int p=((2*dy)-dx);

int x=x1;
int y=y1;

putpixel(x,y,color);

while(x<x2)
{
x++;

if(p<0)
p+=two_dy;

else
{
y+=inc_dec;
p+=two_dy_dx;
}

putpixel(x,y,color);
}
}

else
{
int two_dx=(2*dx);
int two_dx_dy=(2*(dx-dy));
int p=((2*dx)-dy);

int x=x1;
int y=y1;

putpixel(x,y,color);

while(y!=y2)
{
y+=inc_dec;

if(p<0)
p+=two_dx;

else
{
x++;
p+=two_dx_dy;
}

putpixel(x,y,color);
}
}
}

//————————– show_screen( ) —————————//

void show_screen( )
{
setfillstyle(1,1);
bar(208,26,430,38);

settextstyle(0,0,1);
outtextxy(218,29,”Reflection Transformation”);
for(int count=0;count<=30;count++)
outtextxy(229,450,”Press any Key to exit.”);
}

//—————————– THE END ——————————-//

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