09. tranformation.cpp

// C code to implement basic
// transformations in OPENGL
#include <stdio.h>
#include <math.h>
#include <time.h>
#include <GL/glut.h>
 
// window size
#define maxWD 640
#define maxHT 480
 
// rotation speed
#define thetaSpeed 0.05

int matX[4],matY[4];
int new_matX[4],new_matY[4];
// this creates delay between two actions
void delay(unsigned int mseconds)
{
    clock_t goal = mseconds + clock();
    while (goal > clock())
        ;
}
 
// this is a basic init for the glut window
void myInit(void)
{
    glClearColor(1.0, 1.0, 1.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0.0, maxWD, 0.0, maxHT);
    glClear(GL_COLOR_BUFFER_BIT);
    glFlush();
}
 
// this function just draws a point
void drawPoint(int x, int y)
{
    glPointSize(4.0);
    glColor3f(0.0f, 0.0f, 1.0f);
    glBegin(GL_LINES);
    glVertex2i(x, y);
    glEnd();
}


void drawP(int matX[4], int matY[4])
{
    glPointSize(1.0);
    glColor3f(0.0f, 0.0f, 1.0f);
    glBegin(GL_POLYGON);
    glVertex2i(matX[0], matY[0]);
	glVertex2i(matX[1], matY[1]);
	glVertex2i(matX[2], matY[2]);
	glVertex2i(matX[3], matY[3]);
    glEnd();
}
void drawSq(int matX[4],int matY[4])
{
	int i,j;
	for(i=0;i<4;i++)
	{
		drawPoint(matX[i],matY[i]);
	}
}

 
void rotateAroundPt(int matX[4],int matY[4], int angle, int cx, int cy)
{
    float theta = 0.0;
   // while (1) 
	{
		 delay(10);
        glClear(GL_COLOR_BUFFER_BIT);
     
		drawP(matX,matY);
        // update theta anticlockwise rotation
		   int xf[4], yf[4];
        theta = ((float)angle * 3.14159) / 180.0;
        // check overflow

       /* if (theta >= (2.0 * 3.14159))
            theta = theta - (2.0 * 3.14159);
		*/
        // actual calculations..
		for(int i=0;i<4;i++)
		{
			xf[i] =  (matX[i] * cos(theta)) - (matY[i] * sin(theta));
			yf[i] = (matX[i] * sin(theta)) + (matY[i]  * cos(theta));
		}
 
        // drawing the centre point
        drawP(xf, yf);
 
        // drawing the rotating point
        drawP(xf, yf);
        glFlush();
        // creating a delay
        // so that the point can be noticed
       
    }
}
 
// this function will translate the point
void translatePoint(int matX[4], int matY[4], int tx, int ty)
{
	int fx[4],fy[4];
	for(int i=0;i<4;i++)
	{
		fx[i] = matX[i];
		fy[i] = matY[i];
	}
    
    //while (1)
	{
		   delay(10);
        glClear(GL_COLOR_BUFFER_BIT);
		drawP(matX, matY); // drawing the point
        // update
		for(int i=0;i<4;i++)
		{
			fx[i] = fx[i] + tx;
			fy[i] = fy[i] + ty;
		}
 
        // check overflow to keep point in screen
        /*if (px > maxWD || px < 0 || py > maxHT || py < 0) {
            px = fx;
            py = fy;
        }*/
 
        drawP(fx, fy); // drawing the point
 
        glFlush();
        // creating a delay
        // so that the point can be noticed
     
    }
}
 
// this function draws
void scalePoint(int matX[4], int matY[4], int sx, int sy)
{
    int fx[4], fy[4];
    //while (1) 
	{
		    delay(500);
        glClear(GL_COLOR_BUFFER_BIT);
		drawP(matX,matY);
        // update
		for(int i=0;i<4;i++)
		{

			fx[i] = matX[i] * sx;
			fy[i] = matY[i] * sy;
		}
 
        drawP(fx, fy); // drawing the point
 
        glFlush();
        // creating a delay
        // so that the point can be noticed
    
    }
}
 
// Actual display function
void myDisplay(void)
{
    int opt,i;
	int tx,ty;
	int rotX,rotY,angle;
	int sx,sy;
	printf("\nEnter the four coordinates of the square : \n");
	for(i=0;i<4;i++)
	{
		scanf("%d",&matX[i]);
		scanf("%d",&matY[i]);
	}
	printf("\nThe four coordinates of the square are : \n");

	glClear(GL_COLOR_BUFFER_BIT);
	drawP(matX,matY);
	  glFlush();
	
    while(1){
	printf("\nEnter\n\t<1> for translation"
           "\n\t<2> for rotation"
           "\n\t<3> for scaling\n\t:");
    scanf("%d", &opt);
    printf("\nGo to the window...");
    switch (opt) {
    case 1:
		
		printf("\nEnter the X displacement : ");
		scanf("%d",&tx);
		printf("\nEnter the Y displacement : ");
		scanf("%d",&ty);
        translatePoint(matX, matY, tx, ty);
        break;
    case 2:
		printf("Enter the angle of rotation : ");
		scanf("%d",&angle);
		/*printf("\nEnter the point of rotation : \n");
		scanf("%d",&rotX);
		scanf("%d",&rotY);*/
        rotateAroundPt(matX,matY,angle,maxWD / 2, maxHT / 2);
        // point will circle around
        // the centre of the window
        break;
    case 3:
		printf("\nEnter the X scaling : ");
		scanf("%d",&sx);
		printf("\nEnter the Y scaling: ");
		scanf("%d",&sy);
        scalePoint(matX, matY, sx, sy);
        break;
    }
	}
}
 
void main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(maxWD, maxHT);
    glutInitWindowPosition(100, 150);
    glutCreateWindow("Transforming point");
    glutDisplayFunc(myDisplay);
    myInit();
    glutMainLoop();
}