I've been trying to write something that will let me easily manage OpenGL using classes.
I took an approach of having a Drawable class [which shapes/etc would inherit from, and override a draw function], and then using a Controller class to iterate through a table of Drawable classes and draw them all. The only issue that I've noticed that the draw() method is being called from the Drawable class, instead of the Rectangle class. ??
class Drawable {
public:
void draw();
};
class Rectangle : public Drawable {
public:
void draw();
};
class Controller {
public:
Drawable ents[200];
int ent_count;
void frame();
void append(Drawable item); // this will add an object onto the list
Controller();
};
void Drawable::draw() {
// this is the default drawing function, which should be overridden
}
void Rectangle::draw() {
// gl functions here
}
void Controller::frame() {
for(int i=0;i<ent_count,i++) {
ents[i].draw(); // draw all entities on the list
}
// here, a timer would loop back the frame() function
}
void Controller::append(Drawable item) {
ents[ent_count++]=item;
}
int main(void) {
Controller main_controller; // create a controller
Rectangle rect; // create a rectangle
main_controller.append(rect); // insert rectangle into controller list
main_controller.frame(); // start the frame loop
}
[if there are minor typing errors in that, it is because it was written as a summary of the method.] This method that I've tried to use has not been very successful, and I'm pretty sure it has to do with inheritance. Any ideas? Entire source code:
#include <iostream>
#include <GL/glfw.h>
#include <GL/gl.h>
class Drawable {
public:
int x,y;
void draw();
void frame();
void create();
void destroy();
};
void Drawable::create() {
}
void Drawable::draw() {
}
class Rectangle : public Drawable {
public:
int w,h;
unsigned short r,g,b;
Rectangle(int x,int y, int w, int h, unsigned short r, unsigned short g, unsigned short b);
void draw();
};
void Rectangle::draw() {
glColor3ub(r,g,b);
glBegin(GL_QUADS);
glVertex2i(x,y);
glVertex2i(x+w,y);
glVertex2i(x+w,y+h);
glVertex2i(x,y+h);
glEnd();
}
Rectangle::Rectangle(int x,int y, int w, int h, unsigned short r, unsigned short g, unsigned short b) {
this->x=x;
this->y=y;
this->w=w;
this->r=r;
this->g=g;
this->b=b;
}
class Controller {
public:
Controller(int w,int h,int fsaa,bool fs,bool vsync,const char* title);
bool running;
int frame_limit;
Drawable entity[200];
int entity_count;
void fev();
void begin();
void bind();
void append(Drawable item);
};
Controller::Controller(int w,int h,int fsaa,bool fs,bool vsync,const char* title) {
int fullscreen= (fs ? GLFW_FULLSCREEN : GLFW_WINDOW);
bool window=glfwOpenWindow(w,h,0,0,0,0,10,10,fullscreen);
glfwSetWindowTitle(title);
frame_limit=120;
entity_count=0;
std::cout << (window ? "Successfully initialized a window.\n" : "Error initializing window!\n");
}
void Controller::begin() {
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0,640,480,0,0,5);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClearColor(0.4f,0.4f,0.4f,1.0f);
running=true;
fev();
}
void Controller::append(Drawable item) {
entity[entity_count++]=item;
}
void Controller::fev() {
glClear(GL_COLOR_BUFFER_BIT);
for (int i=0;i<entity_count;++i) {
entity[i].draw();
}
glfwSwapBuffers();
if (frame_limit>0) {
glfwSleep(1000/frame_limit*0.001);
}
if (running) {
if (glfwGetKey(GLFW_KEY_ESC) || !glfwGetWindowParam(GLFW_OPENED)) {
running=false;
}
fev();
} else {
std::cout << "terminated!";
}
}
int main(void) {
glfwInit();
Controller main(640,480,0,false,false,"WindTitle");
Rectangle rect(50,50,50,50,50,50,50);
main.append(rect);
main.begin();
}
