Language C++, using Stroustrup\'s GUI . This is to realize Buffon\'s Needle expe
ID: 3841350 • Letter: L
Question
Language C++, using Stroustrup's GUI.
This is to realize Buffon's Needle experiment using Stroustrup's GUI implementation. The mission is to realize a visual effect to gain insight into what this classic experiment is about. Your work is mostly reverse-engineering of what Stroustrup wrote for the textbook demonstration in Chapter 16. Realizing this kind of application may lead you in a common pitfall. I also experienced. Some of the useful posting I found on the web is here.
Draw six, evenly distanced, vertical parallel lines (Figure 1). The window showing them has an data entry field in which user can enter a number of needles to drop on the windows. All the needles are of the same length of the line distance. A "Drop" button will draw the result (Figure 2). The user can repeat drop operations. A "Motion Menu" button will operate three options on the dropped needles:
-"Count" will find out all the needles that crossed any one of the vertical lines. Those needles are colored red, and the ratio of 2 * drop-count / crossed-count is shown in the center of the window (Figure 3).
-"Rotate" will randomly rotate all the dropped needles based on their center positions. Needle's color is reset to black. User can repeal repeat rotation operations (Figure 4).
-"(Un)list" will show the order of drop around the center of each needle. This operation will toggle in the sense that pushing again will erase the shown orders (Figure 5)
It is known that Buffon's experiment does not converge like Monte Carlo experiment. Therefore, increasing drop count does not necessarily result in the accurate estimation (Figure 6). From my experience, you should limit the range of x so that the center of needle should fall from the first half of line distance to the last half of the line distance.
The following pictures shows the output of the game. This is how its suppose to be.
FIGURE 1 Initial Window
FIGURE 2. Drop operation
FIGURE 3. Count Operation
FIGURE 4. Rotate operation
FIGURE 5.(Un)List operation
Once again, the assignment is not meant to ask you to add any functionality to Stroustrup's GUI/Graphic class collection. You must accomplish the required task by the use of the library you created, not adding any method or changing any part of class definition.
Programming Assignment #7 Enter drop count L Drop Quit Motion MenuExplanation / Answer
//MUST BE COMPILED WITH COMPILER FLAG -std=c++11!! Otherwise, lambda functions will not work!
#include "Graph.h"
#include "std_lib_facilities.h"
#include "GUI.h"
#include <iostream>
#include <string>
#include <ctime>
#include <math.h>
using namespace Graph_lib;
using namespace std;
struct Our_window : Graph_lib::Window {
Our_window(Point xy, int w, int h, const string& title);
const static int LEN = 170; //used for the x-values of the green lines; LEN represents the distance between each green line
private:
Button drop_button;
Button quit_button;
Button menu_button;
In_box drop_count;
Menu motion_menu;
Rectangle text_box; //green box
Text approx_pi; //white text on green box that signifies how many intersections we have and what pi is approximated to
bool listed = false; //whether we list drop count or not
vector<Line*> lines; //needles
vector<Text*> drop_order; //drop count of needles
void menu_pressed(); //show the menu
void hide_menu();
void show_text(); //show drop orders
void hide_text(); //hide drop orders
void hide_count();
int intersects(); //how many needle intersections we have
void drop();
void count();
void rotate();
void unlist();
void quit();
};
Our_window::Our_window(Point xy, int w, int h, const string& title)
:Window(xy, w, h, title),
drop_button(Point(x_max() - 100, 0), 50, 20, "Drop", [](Address, Address pw) { reference_to<Our_window>(pw).drop();}),
quit_button(Point(x_max() - 50, 0), 50, 20, "Quit", [](Address, Address pw) { reference_to<Our_window>(pw).quit();}),
menu_button(Point(x_max() - 100, 20), 100, 20, "Motion Menu", [](Address, Address pw) {reference_to<Our_window>(pw).menu_pressed();}),
drop_count(Point(x_max() - 200, 0), 100, 20, "Enter drop count"),
motion_menu(Point(x_max() - 70, 20), 70, 20, Menu::vertical, "Motion Menu"),
text_box(Point(x_max() / 2 - 200, y_max()/2 - 50), 460, 20),
approx_pi(Point(x_max() / 2- 200, y_max()/2 - 35), "Found 0 crossed needles, and estimated pi is inf!")
{
motion_menu.attach(new Button(Point(0,0),0,0, "Count", [](Address, Address pw) {reference_to<Our_window>(pw).count();}));
motion_menu.attach(new Button(Point(0,0),0,0, "Rotate", [](Address, Address pw) {reference_to<Our_window>(pw).rotate();}));
motion_menu.attach(new Button(Point(0,0),0,0, "(Un)list", [](Address, Address pw) {reference_to<Our_window>(pw).unlist();}));
text_box.set_fill_color(Color::dark_green); //background of count display
approx_pi.set_color(Color::white); //text color of count display
approx_pi.set_font_size(17);
attach(drop_button);
attach(quit_button);
attach(drop_count);
attach(motion_menu);
motion_menu.hide();
attach(menu_button);
}
Point center_pt(Line* line) {
//this doesn't belong in the blueprint for Our_window, but it is used by Our_window objects
int c_x = (int)round((line->point(0).x + line->point(1).x) / 2.0);
int c_y = (int)round((line->point(0).y + line->point(1).y) / 2.0);
return Point(c_x, c_y);
}
//supplementary functions :
int Our_window::intersects() {
int crossed = 0;
for (auto line : lines) {
int x1 = line->point(0).x;
int x2 = line->point(1).x;
for (int i = 0; i < 6; i++) { //loop through each green line
int x_green = LEN*(i+1); //this is the x-value of the green line we are checking for intersects
if ((x_green < x2 && x_green > x1) || (x_green > x2 && x_green < x1)) {
//for the needle to intersect, either x1 is on the left side of x_green and x2 on the right side or visa-versa
line->set_color(Color::red);
crossed++;
}
}
}
return crossed;
}
void Our_window::menu_pressed() {
menu_button.hide();
motion_menu.show();
};
void Our_window::hide_menu() {
motion_menu.hide();
menu_button.show();
};
void Our_window::show_text() {
for (auto order : drop_order)
attach(*order);
};
void Our_window::hide_text() {
for (auto order : drop_order)
detach(*order);
};
void Our_window::hide_count() {
//we want to recolor all lines to black and remove the approximation text whenever we press anything other than count
for (auto line : lines)
line->set_color(Color::black); //makes sense to re-color red lines on new drop; we're not counting anymore
detach(text_box);
detach(approx_pi);
}
//main functions
void Our_window::drop() {
int stick_amt = drop_count.get_int();
if (stick_amt < 0) return; //user did not input an integer
int min_x = LEN; //minimum value of pt1 of a stick
int max_x = x_max() - LEN; //maximum value of pt2 of a stick
int x_range = max_x - min_x + 1; //x cannot go out of bounds
int min_y = LEN;
int max_y = y_max() - LEN;
int y_range = max_y - min_y + 1; //your program only limits x - we may get better results if we limit y, as well
int og_size = lines.size(); // used to determine the drop number of every new stick
for (int i = 0; i < stick_amt; i++) {
int rand_angle = rand() % 360;
int x1 = min_x + rand() % x_range;
int y1 = min_y + rand() % y_range;
int x2 = x1 + (int)round(cos(rand_angle)*LEN);
int y2 = y1 + (int)round(sin(rand_angle)*LEN);
Line* line = new Line(Point(x1,y1), Point(x2,y2));
Text* text = new Text(center_pt(line), to_string(og_size + i + 1)); //drop number
lines.push_back(line);
drop_order.push_back(text);
attach(*line);
if (listed)
attach(*text); //if listed is already on, it makes sense to list the new needles
}
hide_count();
hide_menu();
redraw();
}
void Our_window::count() {
int crossed = intersects();
double estimated_pi = 2.0 * lines.size() / crossed;
estimated_pi = round(estimated_pi*100000)/100000; //rounds to 5 decimal pts
string fin = "Found " + to_string(crossed) + " crossed needles, and estimated pi is " + to_string(estimated_pi) + "!";
approx_pi.set_label(fin);
attach(text_box);
attach(approx_pi);
hide_menu();
}
void Our_window::rotate() {
for (int i = 0; i < lines.size(); i++) {
int theta = rand() % 360;
Point ctr = center_pt(lines[i]);
int x1 = ctr.x + (int)round(cos(theta)*(LEN/2));
int x2 = ctr.x - (int)round(cos(theta)*(LEN/2));
int y1 = ctr.y + (int)round(sin(theta)*(LEN/2));
int y2 = ctr.y - (int)round(sin(theta)*(LEN/2));
detach(*lines[i]);
delete lines[i];
lines[i] = new Line(Point(x1,y1), Point(x2,y2)); //set to a new line with the same center and random angle
attach(*lines[i]);
}
hide_count();
hide_menu();
}
void Our_window::unlist() {
listed ? hide_text() : show_text();
listed = !listed;
hide_count();
hide_menu();
}
void Our_window::quit() {
/*in case Our_window is used in a program in which multiple windows are open, we want to make sure
that all objects are deleted and detached when this window is closed. It doesn't matter for this program though -
the program quits entirely on quit(), freeing all memory.*/
for (auto line : lines) {
detach(*line);
delete line;
}
for (auto text : drop_order) {
detach(*text);
delete text;
}
detach(drop_button);
detach(menu_button);
detach(quit_button);
detach(drop_count);
detach(motion_menu);
detach(text_box);
detach(approx_pi);
for (int i = 0; i < motion_menu.selection.size(); i++)
detach(motion_menu.selection[i]);
hide();
}
int main () {
std::srand(std::time(0)); // use current time as seed for random generator
Our_window win(Point(0,0), 1190, 740, "Programming Assignment #7");
vector<Line*> init_lines; //green lines
for (int i = 0; i < 6; i++) {
Line* this_line = new Line(Point(Our_window::LEN*(i+1),30), Point(Our_window::LEN*(i+1),y_max() - 50));
this_line->set_color(Color::dark_green);
init_lines.push_back(this_line);
}
for (auto line_ref : init_lines)
win.attach(*line_ref);
return gui_main();
for (auto line_ref : init_lines)
delete line_ref;
}
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