绘制Bezier曲线

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/z8110/article/details/83094610

#include <iostream>
#include <windows.h>
#include <GL/glut.h>
#include<algorithm>
#define n 3
using namespace std;
//#pragma comment(lib, "glut32.lib")    
int index;
POINT point[n];
GLfloat oldx,oldy,newx,newy;
double ratio;
int flag;
struct draw
{
	GLfloat x;
	GLfloat y;
}get;
draw Array[1200000];
draw Poi;
void init(void)
{
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}
draw reckon(draw x, draw y, double ratio)
{
	draw ans;
	ans.x = y.x - x.x;
	ans.y = y.y - x.y;
	ans.x *= ratio;
	ans.y *= ratio;
	ans.x += x.x;
	ans.y += x.y;
	return ans;
}
draw compute(POINT x, POINT y, double ratio)
{
	POINT temp;
	temp.x = y.x - x.x;
	temp.y = y.y - x.y;
	draw ans;
	ans.x = (FLOAT)temp.x*1.00*ratio / 400 + (FLOAT)x.x*1.00 / 400;
	ans.y = (FLOAT)temp.y*1.00*ratio / 400 + (FLOAT)x.y*1.00 / 400;
	return ans;
}

void display(void)
{
	flag = 0;
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(1.0, 1.0, 1.0);
	glBegin(GL_LINES);

	for (int i = 0; i < n-1; i++)
	{
		if (i == n - 1)
			flag = 1;
		glColor3f((i*1.0+0.5)/(n*1.0), (i*0.9+0.6)/(n*1.0),1.5);
		GLfloat oldx = (FLOAT)point[i].x*1.00 / 400;
		GLfloat oldy = (FLOAT)point[i].y*1.00 / 400;
		GLfloat newx = (FLOAT)point[i+1].x*1.00 / 400;
		GLfloat newy = (FLOAT)point[i+1].y*1.00 / 400;
		glBegin(GLU_POINT);
		glVertex2f(oldx, oldy);
		glBegin(GLU_POINT);
		glVertex2f(newx, newy);
		glBegin(GL_LINES);
		glVertex2f(oldx, oldy);
		glVertex2f(newx, newy);
		glEnd();
	}
	int cnt = 0;
	for (double deep = 0.0;deep < abs(point[0].x-point[1].x); deep += 0.1)
	{
		ratio = deep / abs(point[0].x - point[1].x)*1.0;
		Poi = reckon(compute(point[0],point[1],ratio),compute(point[1],point[2],ratio),ratio);
		Array[cnt].x = Poi.x;
		Array[cnt++].y = Poi.y;
	}
	glBegin(GL_POINTS);
	for (int i = 0; i < cnt; i++)
	{
		glVertex2f(Array[i].x, Array[i].y);
	}

	glutSwapBuffers();

	glEnd();
	glFlush();
}
void motion(int x, int y)
{
	point[index].x = x;
	point[index].y = 400 - y;
}
void mouse(int button, int state, int x, int y)
{
	if (button == GLUT_LEFT_BUTTON)
	{
		if (state == GLUT_DOWN)
		{
			glutMotionFunc(motion);
			if (index < 3)
			{
				cout << point[index].x << endl;
				cout << point[index++].y << endl;
			}

		}
	}
}
int main(int argc, char **argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(400, 400);
	glutCreateWindow("I love OpenGl");
	init();
	glutDisplayFunc(display);
	glutMouseFunc(mouse);

	glutPassiveMotionFunc(motion);
	glutIdleFunc(display);
	glutMainLoop();
	for (int i = 0; i < 100; i++)
	{
		cout << Array[i].x << endl;
		cout << Array[i].y << endl;
	}
	return 0;
}