1.turtle.h
#ifndef _TURTLE_H_
#define _TURTLE_H_
#include <vector>
class CairoInner;
class Turtle {
public:
Turtle();
~Turtle();
void start(const std::vector<float> &A);
void restore(std::vector<float> &A);
void get_point(std::vector<float> &A);
void forward(int L);
void go(int L);
void left(float angle);
void right(float angle);
void drawend();
void resize(int with, int height);
void setColor(int r, int g, int b, int a);
void setPenWidth(int w);
void save(const char *path);
private:
CairoInner *inner;
float P[3];
int wt;
int ht;
};
#endif
2.turtle.cpp
#include <stdio.h>
#include <math.h>
#include <cairo.h>
#include "turtle.h"
class CairoInner {
public:
CairoInner();
~CairoInner();
cairo_surface_t *surface;
cairo_t *cr;
};
Turtle::Turtle()
{
inner = new CairoInner();
if(inner != NULL)
{
}
}
Turtle::~Turtle()
{
if(inner != NULL)
{
if(inner->cr != NULL)
{
cairo_destroy(inner->cr);
inner->cr = NULL;
}
delete inner;
inner = NULL;
}
}
void Turtle::start(const std::vector<float> &A)
{
P[0] = A[0];
P[1] = A[1];
P[2] = A[2];
cairo_move_to(inner->cr, P[0], ht-P[1]);
}
void Turtle::restore(std::vector<float> &A)
{
P[0] = A[0];
P[1] = A[1];
P[2] = A[2];
}
void Turtle::get_point(std::vector<float> &A)
{
A[0] = P[0];
A[1] = P[1];
A[2] = P[2];
}
void Turtle::setColor(int r, int g, int b, int a)
{
double r2 = (double)r / 255;
double g2 = (double)g / 255;
double b2 = (double)b / 255;
double a2 = (double)a / 255;
if(r2 > 1.0)
{
r2 = 1.0;
}
if(g2 > 1.0)
{
g2 = 1.0;
}
if(b2 > 1.0)
{
b2 = 1.0;
}
if(a2 > 1.0)
{
a2 = 1.0;
}
cairo_set_source_rgba(inner->cr,r2,g2,b2,a2);
}
void Turtle::setPenWidth(int w)
{
cairo_set_line_width(inner->cr, w);
}
void Turtle::save(const char *path)
{
cairo_surface_write_to_png(inner->surface, path);
}
void Turtle::resize(int width, int height)
{
inner->surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
inner->cr = cairo_create(inner->surface);
wt = width;
ht = height;
}
void Turtle::forward(int L)
{
float x1 = P[0] + L * cos(P[2]*M_PI/180);
float y1 = P[1] + L * sin(P[2]*M_PI/180);
cairo_line_to(inner->cr, x1, ht-y1);
P[0] = x1;
P[1] = y1;
}
void Turtle::go(int L)
{
float x1 = P[0] + L * cos(P[2]*M_PI/180);
float y1 = P[1] + L * sin(P[2]*M_PI/180);
P[0] = x1;
P[1] = y1;
}
void Turtle::left(float angle)
{
P[2] += angle;
}
void Turtle::right(float angle)
{
P[2] -= angle;
}
void Turtle::drawend()
{
cairo_stroke(inner->cr);
}
CairoInner::CairoInner()
{
surface = NULL;
cr = NULL;
}
CairoInner::~CairoInner()
{
surface = NULL;
cr = NULL;
}
3.lsystem.h
#ifndef _L_SYSTEM_H_
#define _L_SYSTEM_H_
#include <string>
#include <map>
class Turtle;
struct LSRule {
float angle;
std::string axiom;
std::vector<std::string> P;
};
class LSystem {
public:
LSystem(Turtle *turtle);
~LSystem();
void run(const LSRule &LS, const std::vector<float> &A, int L, int n);
private:
std::map<char, std::string> plot_v;
Turtle *m_turtle;
};
#endif
4.lsystem.cpp
#include <iostream>
#include <stack>
#include "turtle.h"
#include "lsystem.h"
using namespace std;
LSystem::LSystem(Turtle *turtle)
{
m_turtle = turtle;
plot_v = {
std::pair<char, std::string>('F', "Move forward by line length drawing a line"),
std::pair<char, std::string>('f', "Move forward by line length without drawing a line"),
std::pair<char, std::string>('+', "Turn left by turning angle"),
std::pair<char, std::string>('-', "Turn right by turning angle"),
std::pair<char, std::string>('[', "push"),
std::pair<char, std::string>(']', "pop")
};
}
LSystem::~LSystem()
{
m_turtle = NULL;
}
void LSystem::run(const LSRule &LS, const std::vector<float> &A, int L, int n)
{
float angle = LS.angle;
std::string axiom = LS.axiom;
std::vector<std::string> P = LS.P;
int i = 0;
std::string new_str = axiom;
while(i < n)
{
std::string s;
for(char alpha : new_str)
{
int k = 0;
for(std::string rule : P)
{
int pos = rule.find("->");
if(pos != std::string::npos)
{
std::string origin = rule.substr(0, pos);
std::string desti = rule.substr(pos+2, rule.length()-pos-2);
if(alpha == origin[0])
{
if(desti != "")
{
s.append(desti);
}
k = 1;
}
}
}
if(k == 0)
{
s.push_back(alpha);
}
}
new_str = s;
std::cout << new_str << std::endl;
i++;
}
m_turtle->start(A);
std::stack<std::vector<float>> s;
std::vector<float> c;
c.resize(3);
for(char alpha : new_str)
{
if(plot_v.find(alpha) == plot_v.end())
{
continue;
}
if(alpha == 'F')
{
m_turtle->forward(L);
}
else if(alpha == 'f')
{
m_turtle->go(L);
}
else if(alpha == '+')
{
m_turtle->left(angle);
}
else if(alpha == '-')
{
m_turtle->right(angle);
}
else if(alpha == '[')
{
m_turtle->get_point(c);
s.push(c);
}
else if(alpha == ']')
{
c = s.top();
s.pop();
m_turtle->restore(c);
}
}
m_turtle->drawend();
}
int main()
{
LSRule LS = {45, "FX", {"F->", "Y->+FX--FY+", "X->-FX++FY-"}};
Turtle turtle;
LSystem lsys(&turtle);
std::vector<float> A = {300, 450, 0};
turtle.resize(800, 800);
turtle.setColor(0, 255, 255, 255);
turtle.setPenWidth(1);
lsys.run(LS, A, 10, 10);
turtle.save("2.png");
return 0;
}
5.编译源码
$ g++ -o example turtle.cpp lsystem.cpp -std=c++11 -I/opt/apps/cairo/include -I/opt/apps/cairo/include/cairo -L/opt/apps/cairo/lib -lcairo -Wl,-rpath=/opt/apps/cairo/lib
6.运行结果
2.png
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