#include <iostream>
#include <cstdlib>

#include <GL/glut.h>

GLfloat light_diffuse[] = {1.0, 0.0, 0.0, 1.0};  /* Red diffuse light. */
GLfloat light_position[] = {1.0, 1.0, 1.0, 0.0};  /* Infinite light location. */

void draw()
{
	glLineWidth(2.0f);
	glColor3d(0,0,0);

	float line[21];

	for(auto i = 0; i < 21; ++i)
		line[i] = 0;

	for(auto y = 0; y < 100; ++y)
	{
		glBegin(GL_LINE_STRIP);
		for(auto x = 0; x < 21; ++x)
		{
			line[x] += (rand() % 5 - 2) / 4.0f;
			glVertex3f(x - 10, line[x], 25.0 - y);
		}
		glEnd();
	}
}

void display()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	draw();
	glutSwapBuffers();
}

void init()
{
	// dvereb:
	srand(time(NULL));

	/* Enable a single OpenGL light. */
	glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
	glLightfv(GL_LIGHT0, GL_POSITION, light_position);
	glEnable(GL_LIGHT0);
	glEnable(GL_LIGHTING);

	/* Use depth buffering for hidden surface elimination. */
	glEnable(GL_DEPTH_TEST);

	/* Setup the view of the cube. */
	glMatrixMode(GL_PROJECTION);
	gluPerspective( /* field of view in degree */ 40.0,
	                /* aspect ratio */ 1.0,
	                /* Z near */ 1.0, /* Z far */ 1000.0);
	glMatrixMode(GL_MODELVIEW);
	gluLookAt(0.0, 7.0, 25.0,  /* eye is at (0,0,5) */
	          0.0, 0.0, 0.0,      /* center is at (0,0,0) */
	          0.0, 1.0, 0.);      /* up is in positive Y direction */
}

int main(int argc, char *argv[])
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutCreateWindow("test opengl program");
	glutDisplayFunc(display);
	init();
	glutMainLoop();

	return 0;
}