mouse

#include <stdafx.h>
#include <glut.h>
#include <cstdlib>
#include <cmath>
using namespace std;

int x = 0;
int y = 0;
bool down = false;

const int N = 1000;

struct P
{
	float x;
	float y;
	float vx;
	float vy;
	float r;
	float g;
	float b;
} p[N];

void display()
{
	glClear(GL_COLOR_BUFFER_BIT);
	glPointSize(3);
	glBegin(GL_POINTS);
	for (int i = 0; i < N; ++i)
	{
		glColor3f(p[i].r, p[i].g, p[i].b);
		glVertex2f(p[i].x, p[i].y);
	}
	glEnd();
	glutSwapBuffers();
}

void timer(int = 0)
{
	display();
	for (int i = 0; i < N; ++i)
	{
		p[i].x += p[i].vx;
		p[i].y += p[i].vy;
		if (down)
		{
			float d = sqrt((p[i].x - x) * (p[i].x - x) + (p[i].y - y) * (p[i].y - y));
			p[i].x += 5 * (x - p[i].x) / d;
			p[i].y += 5 * (y - p[i].y) / d;
		}
	}
	glutTimerFunc(10, timer, 0);
}

void mouse(int button, int state, int ax, int ay)
{
	x = ax;
	y = ay;
	down = state == GLUT_DOWN;
}

void motion(int ax, int ay)
{
	x = ax;
	y = ay;
}

int main(int argc, char **argv)
{
	for (int i = 0; i < N; ++i)
	{
		p[i].x = rand() % 480;
		p[i].y = rand() % 480;
		p[i].vx = rand() % 480 / 100.0 - 2.4;
		p[i].vy = rand() % 480 / 100.0 - 2.4;
		p[i].r = rand() % 200 / 200.0;
		p[i].g = rand() % 200 / 200.0;
		p[i].b = rand() % 200 / 200.0;
	}
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
	glutInitWindowSize(480, 480);
	glutInitWindowPosition(20, 1050 - 480 - 20);
	glutCreateWindow("Mouse");
	glClearColor(0, 0, 0, 1.0);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glOrtho(0, 480, 480, 0, -1, 1);
	glutDisplayFunc(display);
	timer();
	glutMouseFunc(mouse);
	glutPassiveMotionFunc(motion);
	glutMainLoop();
}