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fractal_plant.cpp
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fractal_plant.cpp
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//
// Author: NagaChaitanya Vellanki
//
#include <GLFW/glfw3.h>
#include <iostream>
#include <string>
static float LINE_LENGTH = 0.25f;
static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS) {
glfwSetWindowShouldClose(window, GL_TRUE);
}
}
// variables : X F
// constants : + − [ ]
// start : X
// rules : (X → F-[[X]+X]+F[+FX]-X), (F → FF)
// angle : 25°
// - turn left by 25 degrees
// + turn right by 25 degrees
std::string fractalPlantLSystemRepresentation() {
std::string current("X");
int generation = 0;
while(generation < 11) {
std::string next;
for(std::string::iterator it = current.begin(); it != current.end(); it++) {
switch(*it) {
case 'X':
next.append("F-[[X]+X]+F[+FX]-X");
break;
case 'F':
next.append("FF");
break;
case '-':
next.append("-");
break;
case '+':
next.append("+");
break;
case '[':
next.append("[");
break;
case ']':
next.append("]");
break;
};
}
current = next;
generation++;
//std::cout << "Generation: " << " " << current << std::endl;
}
return current;
}
void drawFractalPlant(float x, float y, std::string lrep) {
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
for(std::string::iterator it = lrep.begin(); it != lrep.end(); it++) {
if(*it == 'F') {
glColor4f(0.5f, 1.0f, 0.0f, 1.0f);
glLineWidth(3.0f);
GLfloat vertices[] = {x, y, x, y + LINE_LENGTH};
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(2, GL_FLOAT, 0, vertices);
glDrawArrays(GL_LINES, 0, 4);
glDisableClientState(GL_VERTEX_ARRAY);
y = y + LINE_LENGTH;
}
if(*it == '[') {
glPushMatrix();
}
if(*it == ']') {
glPopMatrix();
}
if(*it == '-' || *it == '+') {
glTranslatef(x, y, 0.0f);
x = 0.0f;
y = 0.0f;
float angle = ((*it == '-') ? 25.0f : -25.0f);
glRotatef(angle, 0.0f, 0.0f, 1.0f);
}
}
glPopMatrix();
}
int main(int argc, char *argv[]) {
GLFWwindow* window;
if(!glfwInit()) {
return -1;
}
GLFWmonitor* monitor = glfwGetPrimaryMonitor();
const GLFWvidmode* vidmode = glfwGetVideoMode(monitor);
window = glfwCreateWindow(vidmode->width, vidmode->height, "Fractal Plant", monitor, NULL);
if(!window) {
glfwTerminate();
return -1;
}
glfwSetKeyCallback(window, key_callback);
glfwMakeContextCurrent(window);
int width, height;
glfwGetFramebufferSize(window, &width, &height);
float x;
float y;
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0f, width, 0.0f, height, 0.0, 1.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
std::string lrep = fractalPlantLSystemRepresentation();
while(!glfwWindowShouldClose(window)) {
drawFractalPlant(width / 2, height / 8, lrep);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}