Prog12_BezierCurve.cpp

#include<iostream>
#include<math.h>
#include<GL/glut.h>
using namespace std;
float x1[4], yc[4];
int flag = 0;
void myInit() {
	glClearColor(1, 1, 1, 1);
	glColor3f(1, 1, 1);
	glPointSize(5);
	gluOrtho2D(0, 500, 0, 500);
}

void drawPixel(float x, float y) {
	glBegin(GL_POINTS);
	glVertex2f(x, y);
	glEnd();
}
void display(){
  glClear(GL_COLOR_BUFFER_BIT);
	int i;
	double t;
	glColor3f(0, 0, 0);
	glBegin(GL_POINTS);
  for(t=0;t<1;t+=0.005){
    double xt = pow(1 - t, 3) * x1[0] + 3 * t * pow(1 - t, 2) * x1[1] + 3 * pow(t, 2) * (1 - t) * x1[2] + pow(t, 3) * x1[3];
		double yt = pow(1 - t, 3) * yc[0] + 3 * t * pow(1 - t, 2) * yc[1] + 3 * pow(t, 2) * (1 - t) * yc[2] + pow(t, 3) * yc[3];
		glVertex2f(xt, yt);
  }
  glColor3f(1, 0, 0);
	for (i = 0; i < 4; i++) {
		glVertex2f(x1[i], yc[i]);
		glEnd();
		glFlush();
	}
}
void mymouse(int btn, int state, int x, int y)
{
	if (btn == GLUT_LEFT_BUTTON && state == GLUT_DOWN && flag < 4)
	{
		x1[flag] = x;
		yc[flag] = 500 - y;
		cout << " X: " << x << " Y" << 500 - y << endl;
		glPointSize(3);
		glColor3f(1, 0, 0);
		glBegin(GL_POINTS);
		glVertex2i(x, 500 - y);
		glEnd();
		glFlush();
		flag++;
	}
	if (flag >= 4 && btn == GLUT_LEFT_BUTTON)
	{
		glColor3f(0, 0, 1);
		display();
		flag = 0;
	}
}
int main(int argc, char* argv[]) {
	glutInit(&argc, argv);
	/*
	//USE KEYBOARD
	cout << "Enter the x co-ordinates";
	cin >> x1[0] >> x1[1] >> x1[2] >> x1[3];
	cout << "Enter y co-ordinates";
	cin >> yc[0] >> yc[1] >> yc[2] >> yc[3];
	//END KEYBOARD
	*/
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(500, 500);
	glutInitWindowPosition(0, 0);
	glutCreateWindow("BZ");
	glutDisplayFunc(display);
	glutMouseFunc(mymouse); //INCLUDE FOR MOUSE, REMOVE FOR KEYBOARD
	myInit();
	glutMainLoop();
}