double triangleArea(punct a, punct b, punct c) {
	return abs((a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y)) / 2);
}

bool pointInTriangle(punct a, punct b, punct c, punct m) {
	if (triangleArea(a, b, c) == triangleArea(a, b, m) + triangleArea(a, c, m) + triangleArea(b, c, m))
		return true;
	return false;
}



void desen() // procedura desenare
{
	if (p.size() >= 2) {
		glLineWidth(3);
		glBegin(GL_LINES);
		glColor3f(0, 0, 0);

		for (int i = 0; i < p.size() - 1; i++) {
			glVertex2i(p[i].x, p[i].y);
			glVertex2i(p[i + 1].x, p[i + 1].y);
		}

		if (p.size() == n) {
			glVertex2i(p[0].x, p[0].y);
			glVertex2i(p[n - 1].x, p[n - 1].y);


		}
		glEnd();

		if (p.size() == n) {
			int k = 0;
			for (int i = 1; i < p.size(); i++) {
				if (p[k].x > p[i].x)
					k = i;
			}



			glEnable(GL_POINT_SMOOTH);
			glPointSize(10);
			glBegin(GL_POINTS);


			for (int i = 0; i < p.size(); i++) {
				punct v, w, pct;
				if (i == p.size() - 1) {
					v = vect[i];
					w = vect[0];
					pct = p[0];
				}
				else {
					v = vect[i];
					w = vect[i + 1];
					pct = p[i + 1];
				}
				if ((prodVect(v, w).z  * prodVect(vect[k == 0 ? vect.size() - 1 : k - 1], vect[k]).z) > 0) {
					int nr = 0;
					punct a, b, c;
					if (i == p.size() - 1) {
						a = p[i];
						b = p[0];
						c = p[1];
					}
					else if (i == p.size() - 2) {
						a = p[i];
						b = p[i + 1];
						c = p[0];
					}
					else {
						a = p[i];
						b = p[i + 1];
						c = p[i + 2];
					}
					for (int j = 0; j < p.size(); j++) {
						if (pointInTriangle(a, b, c, p[j]))
							nr++;
					}
					cout << nr;
					if (nr == 3) {
						vfPrin.push_back(b);
					}
					glColor3f(1, 0, 0);
				}
				else {
					glColor3f(0, 0, 1);
				}
				glVertex2i(pct.x, pct.y);
			}



			glEnd();
			glColor3f(0, 0, 0);
			for (int i = 0; i < vfPrin.size(); i++) {
				glRasterPos2i(vfPrin[i].x + 15, vfPrin[i].y + 15);
				glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18, 'P');
			}
		}






	}

	glFlush();
}