#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <math.h>

#include <GL/freeglut.h>

void draw_axis() {
	glColor3f(1, 1, 1);
	glBegin(GL_LINES);

	glVertex2f(0, 0);
	glVertex2f(1, 0);
	glVertex2f(0, 0);
	glVertex2f(0, 1);

	glVertex2f(1, 0);
	glVertex2f(0.9, 0.1);
	glVertex2f(1, 0);
	glVertex2f(0.9, -0.1);

	glVertex2f(0, 1);
	glVertex2f(0.1, 0.9);
	glVertex2f(0, 1);
	glVertex2f(-0.1, 0.9);

	glEnd();
}

void draw_grid() {
	glColor3f(0.2, 0.2, 0.2);

	glBegin(GL_LINES);

	for (int i = -10; i < 10; ++i) {
		glVertex2f(i, -10);
		glVertex2f(i, 10);
	}

	for (int i = -10; i < 10; ++i) {
		glVertex2f(-10, i);
		glVertex2f(10, i);
	}

	glEnd();

	glColor3f(0.5, 0.5, 0.5);

	glBegin(GL_LINES);

	glVertex2f(-10, 0);
	glVertex2f(10, 0);

	glVertex2f(0, -10);
	glVertex2f(0, 10);

	glEnd();
}

void draw_function(double from, double to, double step, double(*fun)(double)) {
	glColor3f(0.9f, 0.5f, 0.2f);
	glLineWidth(2);
	glBegin(GL_LINES);

	for (float i = from; i < to; i += step) {
		double current = fun(i);
		double next = fun(i + step);

		glVertex2f(i, current);
		glVertex2f(i + step, next);
	}

	glEnd();
}

double tp(double x, double a, double b, double c, double d) {
	return a * x * x * x + b * x * x + c * x + d;
}

double example_function(double x) {
	return tp(x, 1, 5, 5, -1);
}

static void display(void) {
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


	draw_grid();
	draw_axis();
	draw_function(-10, 10, 0.01, &example_function);

	glutSwapBuffers();
}

static void keyboard(unsigned char key, int x, int y) {
	printf("Pressed %c key\n", key);
	if(key == 'q') {
		exit(0);
	}
}

void enableMultisample(int msaa) {
	if (msaa) {
		glEnable(GL_MULTISAMPLE);
		glHint(GL_MULTISAMPLE_FILTER_HINT_NV, GL_NICEST);

		// detect current settings
		GLint iMultiSample = 0;
		GLint iNumSamples = 0;
		glGetIntegerv(GL_SAMPLE_BUFFERS, &iMultiSample);
		glGetIntegerv(GL_SAMPLES, &iNumSamples);
		printf("MSAA on, GL_SAMPLE_BUFFERS = %d, GL_SAMPLES = %d\n", iMultiSample, iNumSamples);
	} else {
		glDisable(GL_MULTISAMPLE);
		printf("MSAA off\n");
	}   
}

int main(int argc, char **argv) {
	glutInit(&argc, argv);
	glutInitWindowSize(600, 600);
	glutSetOption(GLUT_MULTISAMPLE, 8);
	glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_MULTISAMPLE);
	glutCreateWindow("cme");

	enableMultisample(1);

	printf("OpenGL version = %s\n", glGetString(GL_VERSION));

	glutDisplayFunc(display);
	glutKeyboardFunc(keyboard);

	glScalef(0.1, 0.1, 0.1);
	glClearColor(0.0, 0.0, 0.0, 1.0);


	glutMainLoop();
}