The following Source code performs the following 2 dimensional transformations:
- Translations
- Scaling
- Rotation
- Shearing
- Reflection
- Composite Transformations
Source Code:
#include
#include
#include
#include
typedef float Matrix3x3 [3][3];
Matrix3x3 theMatrix;
int NEdges;
float ptsIni[20][2];
float ptsFin[20][2];
float refpt[2];
float RotAngle;
float TransDistX,TransDistY;
float ScaleX,ScaleY;
int choice,choiceRef,choiceShear;
float slope,yIntercept;
float shearValue;
void matrixSetIdentity(Matrix3x3 m)
// Initialises the matrix as Unit Matrix
{
int i, j;
for (i=0; i<3; i++)
for (j=0; j<3; j++)
m[i][j] = (i == j);
}
void matrixPreMultiply(Matrix3x3 a , Matrix3x3 b)
// Multiplies matrix a times b, putting result in b
{
int i,j;
Matrix3x3 tmp;
for (i = 0; i < 3; i++)
for (j = 0; j < 3; j++)
tmp[i][j] = a[i][0]*b[0][j] + a[i][1]*b[1][j] + a[i][2]*b[2][j];
for (i = 0; i < 3; i++)
for (j = 0; j < 3; j++)
theMatrix[i][j] = tmp[i][j];
}
void Translate(int tx, int ty)
{
Matrix3x3 m;
matrixSetIdentity(m);
m[0][2] = tx;
m[1][2] = ty;
matrixPreMultiply(m, theMatrix);
}
void Scale(float sx , float sy)
{
Matrix3x3 m;
matrixSetIdentity(m);
m[0][0] = sx;
m[0][2] = (1 - sx)*refpt[0];
m[1][1] = sy;
m[1][2] = (1 - sy)*refpt[1];
matrixPreMultiply(m , theMatrix);
}
void Rotate(float a)
{
Matrix3x3 m;
matrixSetIdentity(m);
a = a*22/1260;
m[0][0] = cos(a);
m[0][1] = -sin(a) ;
m[0][2] = refpt[0]*(1 - cos(a)) + refpt[1]*sin(a);
m[1][0] = sin(a);
m[1][1] = cos(a);
m[1][2] = refpt[1]*(1 - cos(a)) - refpt[0]*sin(a);
matrixPreMultiply(m , theMatrix);
}
void Reflect(int xy)
{
Matrix3x3 m;
matrixSetIdentity(m);
if(xy == 2)
m[1][1] = -1;
if(xy == 3)
m[0][0] = -1;
matrixPreMultiply(m , theMatrix);
}
void Shear(int xy)
{
Matrix3x3 m;
matrixSetIdentity(m);
if(xy == 1)
m[0][1] = shearValue;
if(xy == 2)
m[1][0] = shearValue;
matrixPreMultiply(m , theMatrix);
}void TransformPoints(void)
{
int k;
float tmp ;
for (k = 0 ; k ");
scanf("%d",&NEdges);
printf("Enter %d Co-ordinate pairs \n",NEdges);
int PlotCt;
for(PlotCt=0 ; PlotCt");
scanf("%d",&choice);
switch(choice)
{
case 1: printf("Enter reference point Co-ordinates:\n=>");
scanf("%f %f",&refpt[0],&refpt[1]);
printf("Enter Angle of Rotation\n=>");
scanf("%f",&RotAngle);
printf("Enter translation along X & Y\n=>");
scanf("%f%f",&TransDistX , &TransDistY);
printf("Enter Scaling ratios along X & Y\n=>");
scanf("%f%f",&ScaleX , &ScaleY);
break;
case 2: printf("Enter translation along X & Y\n=>");
scanf("%f%f",&TransDistX , &TransDistY);
break;
case 3: printf("Enter Angle of Rotation\n=>");
scanf("%f",&RotAngle);
printf("Enter reference point Co-ordinates:\n=>");
scanf("%f %f",&refpt[0],&refpt[1]);
break;
case 4: printf("Enter Scaling ratios along X & Y\n=>");
scanf("%f%f",&ScaleX , &ScaleY);
break;
case 5: printf("Enter your choice number for Reflection about:\n
1.Origin\n 2.X-axis\n 3.Y-axis\n 4.y = mx+c\n=>");
scanf("%d",&choiceRef);
if(choiceRef == 4)
{
printf("Enter m & c: \n=>");
scanf("%f %f",&slope,&yIntercept);
}
break;
case 6: printf("Enter your choice number to shear about:\n
1.x-axis\n 2.y-axis\n=>");
scanf("%d",&choiceShear);
printf("Enter shear value:\n=>");
scanf("%f",&shearValue);
break;
default: printf("Please enter a valid choice!!!\n");
return 0;
}
glutDisplayFunc(display);
glutMainLoop();
return 0;
}
OUTPUT:
1 . Translation
INPUT :
4 // No. of vertices of Polygon 20 20 //(x,y) Co-ordinates of Vertices 100 20 100 100 20 100 2 // Selected option 2 for Translation -50 -140 // Translation along X & Y
OUTPUT :
2 . Rotation
INPUT :
4 // No. of vertices of Polygon 20 20 // (x,y) Co-ordinates of Vertices 100 20 100 100 20 100 3 // Choice no. for Rotation 60 // Angle of Rotation in Degrees -50 -50 // Reference point Co-ordinates
OUTPUT :
3 . Scaling
INPUT :
4 // No. of vertices of Polygon 20 20 // (x,y) Co-ordinates of Vertices 100 20 100 100 20 100 4 // Choice no. for Scaling 0.5 0.5 // Scaling factors along X & Y
OUTPUT :
4 . Reflection
About arbitrary line y=mx+c
INPUT :
4 // No. of vertices of Polygon 20 20 // (x,y) Co-ordinates of Vertices 100 20 100 100 20 100 5 // Choice no. for Reflection 4 // Choice for Reflection about y=mx+c 1 -30 // m & c values
OUTPUT :
5 . Shearing
X-direction Shear
INPUT :
4 // No. of vertices of Polygon 20 20 // (x,y) Co-ordinates of Vertices 100 20 100 100 20 100 6 // Choice no. for Shearing 1 // Choice no. for Shear about X axis 1.5 // Shear Coefficient
OUTPUT :
6 . Composite Transformation
INPUT :
4 // No. of vertices of Polygon 20 20 // (x,y) Co-ordinates of Vertices 100 20 100 100 20 100 1 // Choice no. for Comp. Transf. -50 -50 // Reference Point Co-ordinates 60 // Angle of Rotation in Degrees -40 -80 // Translation along X & Y 1.5 1.5 // Scaling factors along X & Y
OUTPUT :
Help Index 
Thanks for such a wonderful code, will you please answer my doubts
1.which header file required?
2.what/where is display function?
waiting for reply eagerly…