Projectiles
Author
I am trying to create a 2d asteroids-like game with c++ in directx and was wondering how do you keep track of the projectiles? I can think of a method of two but I'd like to know if there is an appropriate/good way of doing it?
Author
Containers are a new thing for me. I went through the page you linked and didn't wholly understood it. I have a couple of questions. How can you acces and/or change a particular element of the list? Can you make a list of structures? Can you pass this/a list/container as a parameter to a function?
Hey
I would probably go with using vectors.
I don't know if it's the best solution or the worst but i know it works, so i will try to explain it as best i can [rolleyes]
So the above example shows how to use a vector it's not particularly useful but it's simple, Basically we declare a vector on this line
'std::vector<type> name'
and then on this line add a new object with the .push_back(object) function.
'My_Vector.push_back(Counter);'
i see no reason why a structure would not work as the type, but i've never tried too so i may be wrong, i know that Classes work and will show how to use them with vectors in the next example.
Ofcourse you'll probably also like to know how to delete an object, this next example shows how to using basically the same code as above.
Note : the vector system will automatically move the other entries back if you delete an entry in the middle.
Ok i hope this helped you and for your other question yes vectors can be passed as a parameter to a function if you need an example just ask, if you have any other questions i'll be happy to answer them aswell.
and if you need some more info Here
PS : i've probably made alot of mistakes in my code as i haven't been programming for that long.
I would probably go with using vectors.
I don't know if it's the best solution or the worst but i know it works, so i will try to explain it as best i can [rolleyes]
#include <vector>#include <iostream>using namespace std;vector<int> My_Vector;int Counter;int main(){ while(true) { //This will add a new int to the vector My_Vector.push_back(Counter); for(int a = 0; a<My_Vector.size();a++) { //The vector can then be accessed similarly to an array //You can also access it by using My_Vector.at(index) //I'm not clear on the difference cout<<My_Vector[a]; }; cout<<"\n"; Counter++; system("Pause"); };};So the above example shows how to use a vector it's not particularly useful but it's simple, Basically we declare a vector on this line
'std::vector<type> name'
and then on this line add a new object with the .push_back(object) function.
'My_Vector.push_back(Counter);'
i see no reason why a structure would not work as the type, but i've never tried too so i may be wrong, i know that Classes work and will show how to use them with vectors in the next example.
#include <vector>#include <iostream>using namespace std;void Add_Animal();class Animal{public: void eat(); void sleep(); double weight; double height;};vector<Animal> My_Vector;int main(){ while(true) { Add_Animal(); Add_Animal(); for(int a = 0;a<My_Vector.size();a++) { My_Vector[a].eat(); My_Vector[a].weight = My_Vector[a].weight + 1; }; system("Pause"); };};void Add_Animal(){ Animal Temp; Temp.height = 100; Temp.weight = 100; My_Vector.push_back(Temp);};void Animal::eat(){ cout<<"\n"<<"Animal Eating!";};void Animal::sleep(){ cout<<"\n"<<"Animal Sleeping!";};Ofcourse you'll probably also like to know how to delete an object, this next example shows how to using basically the same code as above.
Note : the vector system will automatically move the other entries back if you delete an entry in the middle.
#include <vector>#include <iostream>using namespace std;void Add_Animal();void Delete_Animal(int index);class Animal{public: void eat(); void sleep(); double weight; double height;};vector<Animal> My_Vector;int main(){ while(true) { Add_Animal(); Add_Animal(); for(int a = 0;a<My_Vector.size();a++) { My_Vector[a].eat(); My_Vector[a].weight = My_Vector[a].weight + 1; }; Delete_Animal(1); system("Pause"); };};void Add_Animal(){ Animal Temp; Temp.height = 100; Temp.weight = 100; My_Vector.push_back(Temp);};void Delete_Animal(int index){ My_Vector.erase(My_Vector.begin() + index);};void Animal::eat(){ cout<<"\n"<<"Animal Eating!";};void Animal::sleep(){ cout<<"\n"<<"Animal Sleeping!";};Ok i hope this helped you and for your other question yes vectors can be passed as a parameter to a function if you need an example just ask, if you have any other questions i'll be happy to answer them aswell.
and if you need some more info Here
PS : i've probably made alot of mistakes in my code as i haven't been programming for that long.
Author
Thanks a lot ^_^. Something I'd like to know though is, if you have a container of say structures and you wanted to change the value of one of the members of one of the structures contained how would that be done? I can think of a couple of ways but they all seem so messy.
Basicly what I have in mind is every time the ship shoots, a new missile 'object' is created and pushed back in the container. Then on the main loop using a for loop I would go through all objects in the container and update their position(which is a member of the object).
Edit: Nevermind got it to work although I still think it's unconventional
[Edited by - Antonym on December 12, 2008 10:17:13 AM]
Basicly what I have in mind is every time the ship shoots, a new missile 'object' is created and pushed back in the container. Then on the main loop using a for loop I would go through all objects in the container and update their position(which is a member of the object).
Edit: Nevermind got it to work although I still think it's unconventional
[source ="c++"]#include "global.h"void initGame(list<object>* gameObjects){ //ship object obj; obj.inc1 = 0.2f; obj.max1 = 10; obj.inc2 = 10; obj.max2 = 0.2f; obj.cooldown = 170; gameObjects->push_front(obj); return;}void updateObjects(list<object>* gameObjects, input* inputData){ list<object>::iterator it; for(it = gameObjects->begin(); it != gameObjects->end(); it++){ //Movement Speed if(inputData->move_forward){ if(it->speed1 <= it->max1){ it->speed1 += it->inc1; } } if(inputData->move_backward){ if(it->speed1 >= -(it->max1)){ it->speed1 -= it->inc1; } } //Rotation Speed if(inputData->turn_right){ if(it->speed2 <= it->max2){ it->speed2 += it->inc2; } } if(inputData->turn_left){ if(it->speed2 >= -(it->max2)){ it->speed2 -= it->inc2; } } //Movement it->pos.x -= it->speed1 * sin(it->angle1 * DegtoRad); it->pos.y -= it->speed1 * cos(it->angle1 * DegtoRad); //Direction it->angle1 -= it->speed2; if(it->angle1 < 0) it->angle1 += 360; if(it->angle1 > 360) it->angle1 -= 360; //Rotation it->angle2 += it->speed2; if(it->angle2 < 0) it->angle2 += 360; if(it->angle2 > 360) it->angle2 -= 360; //Screen Edge Reached if(it->pos.x < 0){ it->pos.x += SCREEN_WIDTH; } if(it->pos.x > SCREEN_WIDTH){ it->pos.x -= SCREEN_WIDTH; } if(it->pos.y < 0){ it->pos.y += SCREEN_HEIGHT; } if(it->pos.y > SCREEN_HEIGHT){ it->pos.y -= SCREEN_HEIGHT; } //Attack DWORD timeNow = timeGetTime(); if(inputData->shooting == true){ if((timeNow - it->lastshoot) > it->cooldown){ object obj; obj.pos = it->pos; obj.angle1 = it->angle1; obj.angle2 = it->angle2; obj.speed1 = 10; gameObjects->push_back(obj); it->lastshoot = timeGetTime(); } } } return;}[Edited by - Antonym on December 12, 2008 10:17:13 AM]
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