Sierpinski pentagon: Difference between revisions
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}
</lang>
=={{header|C++}}==
{{trans|D}}
<lang cpp>#include <iomanip>
#include <iostream>
#define _USE_MATH_DEFINES
#include <math.h>
constexpr double degrees(double deg) {
const double tau = 2.0 * M_PI;
return deg * tau / 360.0;
}
const double part_ratio = 2.0 * cos(degrees(72));
const double side_ratio = 1.0 / (part_ratio + 2.0);
/// Define a position
struct Point {
double x, y;
friend std::ostream& operator<<(std::ostream& os, const Point& p);
};
std::ostream& operator<<(std::ostream& os, const Point& p) {
auto f(std::cout.flags());
os << std::setprecision(3) << std::fixed << p.x << ',' << p.y << ' ';
std::cout.flags(f);
return os;
}
/// Mock turtle implementation sufficiant to handle "drawing" the pentagons
struct Turtle {
private:
Point pos;
double theta;
bool tracing;
public:
Turtle() : theta(0.0), tracing(false) {
pos.x = 0.0;
pos.y = 0.0;
}
Turtle(double x, double y) : theta(0.0), tracing(false) {
pos.x = x;
pos.y = y;
}
Point position() {
return pos;
}
void position(const Point& p) {
pos = p;
}
double heading() {
return theta;
}
void heading(double angle) {
theta = angle;
}
/// Move the turtle through space
void forward(double dist) {
auto dx = dist * cos(theta);
auto dy = dist * sin(theta);
pos.x += dx;
pos.y += dy;
if (tracing) {
std::cout << pos;
}
}
/// Turn the turtle
void right(double angle) {
theta -= angle;
}
/// Start/Stop exporting the points of the polygon
void begin_fill() {
if (!tracing) {
std::cout << "<polygon points=\"";
tracing = true;
}
}
void end_fill() {
if (tracing) {
std::cout << "\"/>\n";
tracing = false;
}
}
};
/// Use the provided turtle to draw a pentagon of the specified size
void pentagon(Turtle& turtle, double size) {
turtle.right(degrees(36));
turtle.begin_fill();
for (size_t i = 0; i < 5; i++) {
turtle.forward(size);
turtle.right(degrees(72));
}
turtle.end_fill();
}
/// Draw a sierpinski pentagon of the desired order
void sierpinski(int order, Turtle& turtle, double size) {
turtle.heading(0.0);
auto new_size = size * side_ratio;
if (order-- > 1) {
// create four more turtles
for (size_t j = 0; j < 4; j++) {
turtle.right(degrees(36));
double small = size * side_ratio / part_ratio;
auto distList = { small, size, size, small };
auto dist = *(distList.begin() + j);
Turtle spawn{ turtle.position().x, turtle.position().y };
spawn.heading(turtle.heading());
spawn.forward(dist);
// recurse for each spawned turtle
sierpinski(order, spawn, new_size);
}
// recurse for the original turtle
sierpinski(order, turtle, new_size);
} else {
// The bottom has been reached for this turtle
pentagon(turtle, size);
}
if (order > 0) {
std::cout << '\n';
}
}
/// Run the generation of a P(5) sierpinksi pentagon
int main() {
const int order = 5;
double size = 500;
Turtle turtle{ size / 2.0, size };
std::cout << "<?xml version=\"1.0\" standalone=\"no\"?>\n";
std::cout << "<!DOCTYPE svg PUBLIC \" -//W3C//DTD SVG 1.1//EN\"\n";
std::cout << " \"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n";
std::cout << "<svg height=\"" << size << "\" width=\"" << size << "\" style=\"fill:blue\" transform=\"translate(" << size / 2 << ", " << size / 2 << ") rotate(-36)\"\n";
std::cout << " version=\"1.1\" xmlns=\"http://www.w3.org/2000/svg\">\n";
size *= part_ratio;
sierpinski(order, turtle, size);
std::cout << "</svg>";
}</lang>
=={{header|D}}==
Line 1,107 ⟶ 1,265:
sierpinski Order_:=5, Side:=200
End Sub</lang>
=={{header|zkl}}==
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