16. Cubic Bezier_taylor's.txt

#include <Windows.h>
#include <GL\glew.h>
#include <GL\freeglut.h>
#include <iostream>
#include<stdio.h>
int x1, x2, x3, y11, y2, y3, x4, y4;

void myInit() 
{
	
	glClearColor(1.0, 1.0, 1.0, 0.0);
	glClear(GL_COLOR_BUFFER_BIT);
	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(0, 500, 0, 500);
}

void drawP()
{
	glColor3f(0,0,0);
	glBegin(GL_LINES);
	glVertex2i(x1,y11);
	glVertex2i(x2,y2);
	glEnd();

	glBegin(GL_LINES);
	glVertex2i(x2,y2);
	glVertex2i(x3,y3);
	glEnd();

	glBegin(GL_LINES);
	glVertex2i(x3,y3);
	glVertex2i(x4,y4);
	glEnd();
}
void draw_pixel(int x, int y)
{
	glBegin(GL_POINTS);
	glColor3f (0.0, 0.0, 0.0);
	glVertex2i(x, y);
	glEnd();
}
void draw_gray(int x, int y)
{
	glBegin(GL_POINTS);
	glColor3f (0.5, 0.5, 0.5);
	glVertex2i(x, y);
	glEnd();
}
void draw_curve()
{
	drawP();
	double dt=0.0005;
	double x,y;
	double dfx,dfy,ddfx,ddfy,dddfx,dddfy;
	x=x1;
	y=y11;
	dfx=(3*x2-3*x1)*dt+(3*x1-6*x2+3*x3)*dt*dt+(-x1+3*x2-3*x3+x4)*dt*dt*dt;
	dfy=(3*y2-3*y11)*dt+(3*y11-6*y2+3*y3)*dt*dt+(-y11+3*y2-3*y3+y4)*dt*dt*dt;
	ddfx=2*(3*x1-6*x2+3*x3)*dt*dt+6*(-x1+3*x2-3*x3+x4)*dt*dt*dt;
	ddfy=2*(3*y11-6*y2+3*y3)*dt*dt+6*(-y11+3*y2-3*y3+y4)*dt*dt*dt;
	dddfx=6*(-x1+3*x2-3*x3+x4)*dt*dt*dt;
	dddfy=6*(-y11+3*y2-3*y3+y4)*dt*dt*dt;
	for (double dt=0.0005;dt<1;dt=dt+0.0005)
	{
		draw_pixel(x,y);
		x=x+dfx;
		y=y+dfy;
		dfx=dfx+ddfx;
		dfy=dfy+ddfy;
		ddfx=ddfx+dddfx;
		ddfy=ddfy+dddfy;
	}

}


void myDisplay() 
{
	draw_curve();
	glFlush();
}

void main(int argc, char **argv)
{

	printf( "Enter (x1, y1, x2, y2, x3, y3, x4, y4)\n");
	scanf("%d %d %d %d %d %d %d %d", &x1, &y11, &x2, &y2, &x3, &y3, &x4, &y4);
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
	glutInitWindowSize(500, 500);
	glutInitWindowPosition(0, 0);
	glutCreateWindow("Bezier Cubic Curve Drawing by using Taylor series method");
	myInit();
	glutDisplayFunc(myDisplay);
	glutMainLoop();
}