Messages

76

General / Re: Create unlimited amount of bullets

« on: January 03, 2014, 07:19:48 pm »

I don't see what the problem is with reading my code

You should read that post, it summarizes everything

Ok i have now cleaned up the code a little more + removed everything that is unnecessary for this example. Unused variables mostly.

77

General / Re: Create unlimited amount of bullets

« on: January 03, 2014, 04:27:16 pm »

I don't see what the problem is with reading my code. You don't have to understand it completely. The only thing you need to know is that there's a problem with how i initialize the bullet. It gets added to the world, i've checked that with world->GetBodyCount(), and that it has collision with other boxes. But the world wont move it if i set velocity of the bullet and not even when i set gravity of the world.

Anyway i got a book now that i'm reading although i doubt it will help with this particular problem. This is more of a box2d issue i think at this point.

Edit: I'm not saying it's box2d's fault, i mean it's an issue of me not understanding how box2d needs to do things. If you want i can post the code of when the bullets + box2d did work.

78

General / Re: Create unlimited amount of bullets

« on: January 03, 2014, 02:34:45 am »

But it's hard to learn everything perfectly on your own even with a book.

Yes, you won't get the needed experience just from reading books, that you'll have to acquire by coding, but you'll learn a lot more than just "hacking" away.

Are you able to spot what the error in my code is? I've updated it quite a bit now since i first posted but i can't figure out why the bullet wont move.

Not really, because it's huge spaghetti-code, plus a lot of stuff is left out. Like the whole creation of the Box2D stuff or loading of the textures etc.
Also if you have 10 lines with the the same beginning (e.g. character->bullet.back()), chances are 99.9999999% that you're going wrong about things... which brings as back to learning about classes...

Maybe it's spaghetti code, but it's MY spaghetti code .

Well this is the only things box2d which was left out.

b2Vec2 gravity(0, 0); //normal earth gravity, 9.8 m/s/s straight down!
b2World* world = new b2World(gravity);
world->SetAllowSleeping(true);

This is in the main before the loop starts.

The reason why i haven't posted textures is that i have tested already if that is the issue, but the texture is in the right place. I set gravity and let a test box fall on my bullet sprite which doesn't move and the box2d bullet is in that same location.
Gravity does not affect my bullet box and setting velocity does not affect it either.
I had box2d working fine with bullets when i was using arrays with a set size.

79

General / Re: Create unlimited amount of bullets

« on: January 03, 2014, 01:06:13 am »

I'm not that good with the use of functions and classes yet

Then you should first learn C++ properly. It's complex language and you won't get far with trial-and-error. Get a good C++ book and learn all about classes, functions and especially the STL!

Yes i plan to get a book, but for now i have none. But it's hard to learn everything perfectly on your own even with a book. Are you able to spot what the error in my code is? I've updated it quite a bit now since i first posted but i can't figure out why the bullet wont move.

80

General / Re: Create unlimited amount of bullets

« on: January 03, 2014, 12:46:25 am »

updated it to make sure the bullet doesn't spawn until it's supposed to. It still wont move though, not even if i set gravity in box2d. My testbox will be affected by the gravity though.

81

General / Re: Create unlimited amount of bullets

« on: January 02, 2014, 10:40:06 pm »

Use the member function std::vector::back().

And you should definitely encapsulate your data, this code will be extremely hard to maintain as soon as it grows...

Thanks. I'm not that good with the use of functions and classes yet so i will improve on it later on but i did what you said and am now using std::vector::back(). It is much cleaner, but the code remains the same. I'm not sure why but it only shoots 1 bullet, and that bullet stays at 1 spot.

This is the line to move the bullet, and this worked before i converted to vector so the math is there. it's something else.

//Set bullet pos
for (int i = 0; i < character.bullet.size(); i++){
        character.bullet[i].box.body->SetLinearVelocity(b2Vec2(cos(character.bullet[i].toTargetAngle)*character.bullet[0].speed, sin(character.bullet[i].toTargetAngle)*character.bullet[0].speed));
        character.bullet[i].Sprite.setPosition(character.bullet[i].box.body->GetPosition().x*PPM, character.bullet[i].box.body->GetPosition().y*PPM);
}

82

General / Re: Create unlimited amount of bullets

« on: January 02, 2014, 09:15:57 pm »

all of your code is rong
firstly, you must declare a variable that hold's amount of bullets
after that, you have to declare 2 variables: boath are integers, that hold's x and y positions of the bullet
then you must do how the bullet can fire
for example, if x and y of the bullet is equal to x and y of the enummy, kill it and get a point
you have to declare a variable for point that hold's integer value
as i mentioned , all of your code is rong

The whole point of this was so i don't have to set a max amount of bullets. I did edit my code and got it running now atleast, but it got some issues i'm trying to resolve.

The biggest change was that

character->bullet.size()

needs to be

character->bullet.size()-1

because the vector starts at 0. I also had to change character to a pointer in the function so it saves the push_back.

I will edit with my changes. currently it just fires 1 bullet and it doesn't move anywhere.

83

General / Create unlimited amount of bullets

« on: January 02, 2014, 06:34:18 pm »

Hello.
I previously had a static array where i entered the max amount of bullets as the size of array, for example 100. But i guess this isn't such a good approach for many things where the array size varies, so i heard vectors were a good option instead of arrays because you don't need to memory manage them like with a dynamic array.

But now i need some help in how i'm supposed to use the vector. This is what i have so far. it crashes when it goes into the function newBullet. The problem right now is that the bullet will not be affected by the box2d world. Gravity for example wont affect it.

struct sBox{
    b2BodyDef myBodyDef;
    b2Body* body;
    b2PolygonShape boxShape;
    b2FixtureDef boxFixtureDef;
    sf::RectangleShape Rect;
};

struct sBullet{
    int airTime;
    sf::Vector2f targetVector;
    float toTargetAngle;
    float speed;
    sBox box;
    sf::Sprite Sprite;
};

struct sCharacter{
    std::vector<sBullet> bullet;
    sf::Vector2f targetVector;
    float toTargetAngle;
    int castTime;
    float degreeAngle;;
    int bulletCooldown;
    };
sCharacter character;

void newBullet(sCharacter *character, int PPM, b2World *world, sf::Texture *Texture, sf::Vector2i worldMouseClick, sf::Vector2f position, sf::Vector2f boxSize){
        sBullet bullet;
        character->bullet.push_back(bullet); //+1 to array

        //Calculate bullet path and angle
        character->bullet.back().targetVector.x = worldMouseClick.x - position.x;
        character->bullet.back().targetVector.y = worldMouseClick.y - position.y;
        character->bullet.back().toTargetAngle = atan2(character->bullet.back().targetVector.y, character->bullet.back().targetVector.x);

        //Bullet duration and cooldown
        character->bullet.back().airTime = 500;
        character->bulletCooldown = 20;

        //Set box2d value + spawn body
        character->bullet.back().box.myBodyDef.type = b2_kinematicBody; //this will be a kinematic body
        character->bullet.back().box.myBodyDef.position.Set(position.x/PPM, position.y/PPM); //set the starting position
        character->bullet.back().box.myBodyDef.angle = 0; //set the starting angle
        character->bullet.back().box.body = world->CreateBody(&character->bullet.back().box.myBodyDef);
        character->bullet.back().box.boxShape.SetAsBox(boxSize.x/PPM/2, boxSize.y/PPM/2);
        character->bullet.back().box.boxFixtureDef.shape = &character->bullet.back().box.boxShape;
        character->bullet.back().box.boxFixtureDef.density = 1;
        character->bullet.back().box.body->CreateFixture(&character->bullet.back().box.boxFixtureDef);

        character->bullet.back().box.body->SetActive(true);

        //Set bullet sprite
        character->bullet.back().Sprite.setTexture(Texture[9]);
        character->bullet.back().Sprite.setOrigin(character->bullet.back().Sprite.getLocalBounds().width -20, character->bullet.back().Sprite.getLocalBounds().height / 2);
};

int main(int argc, char** argv){

b2Vec2 gravity(0, 0); //normal earth gravity, 9.8 m/s/s straight down!
b2World* world = new b2World(gravity);
world->SetAllowSleeping(true);


//Bullet Cast time
if (character.castTime >= 0){
    character.castTime -= 1;
}
//Bullet Cooldown
if (character.bulletCooldown > 0){
character.bulletCooldown -= 1;
}

//Start bullet cast
if (mouseOnInventory == false && itemMousePos == -1 && itemOnMouse == -1 && leftButtonDown == 1 && character.castTime == -1 && character.bulletCooldown == 0 && character.currentMana >= character.bullet[0].manaCost){
            worldMouseClick = worldMouse; //Save click pos
            character.castTime = 20;
            character.currentMana -= character.bullet[0].manaCost;
            //Set only character angle
            character.targetVector.x = worldMouseClick.x - Character.getPosition().x;
            character.targetVector.y = worldMouseClick.y - Character.getPosition().y;
            character.toTargetAngle = atan2(character.targetVector.y, character.targetVector.x);
            character.degreeAngle = character.toTargetAngle * 180 / PI;
}

//Fire bullet
if (character.castTime == 0){
            newBullet(&character, PPM, world, Texture, worldMouseClick, Character.getPosition(), sf::Vector2f(40, 40));
            character.bullet.back().box.body->SetTransform(b2Vec2(Character.getPosition().x/PPM, Character.getPosition().y/PPM), character.bullet.back().toTargetAngle);
}
//Set bullet pos
for (int i = 0; i < character.bullet.size(); i++){
        character.bullet[i].box.body->SetLinearVelocity(b2Vec2(cos(character.bullet[i].toTargetAngle)*character.bullet[0].speed, sin(character.bullet[i].toTargetAngle)*character.bullet[0].speed));
}


//Remove bullet after a certain time
for (int i = 0; i < character.bullet.size(); i++){
    if (character.bullet[i].airTime > 0)
        character.bullet[i].airTime -= 1;

    else{
        character.bullet[i].box.body->SetActive(false);
        character.bullet.erase(character.bullet.begin() + i-1);
    }
}

//Box2d
float32 timeStep = 1/60.0;      //the length of time passed to simulate (seconds)
int32 velocityIterations = 10;   //how strongly to correct velocity
int32 positionIterations = 6;   //how strongly to correct position
//Update world. This needs to come after you set positions and before you try to get current positions values.
world->Step(timeStep, velocityIterations, positionIterations);

//Set positon of sprites.
for (int i = 0; i < character.bullet.size(); i++){
character.bullet[i].Sprite.setPosition(character.bullet[i].box.body->GetPosition().x*PPM, character.bullet[i].box.body->GetPosition().y*PPM);
character.bullet[i].Sprite.setRotation(character.bullet[i].box.body->GetAngle()*RADTODEG);
}
}

84

General / Re: main.cpp file suddenly empty but still has file size 29kb

« on: August 10, 2012, 09:20:23 am »

Maybe it was my new computer that ruined it. I got a new computer and was working with my programming, but 1 RAM memory was broken and i didn't realize for quite some time. Maybe when i saved the last time the save got corrupted because of it, and i assumed the save was ok and copied it to my USB.

85

General / Re: main.cpp file suddenly empty but still has file size 29kb

« on: August 10, 2012, 08:56:44 am »

Your file is full of zeroes. Sorry, you have definitely lost everything.

ok thanks :/. Weird how that can happen though. And on 2 places. in USB and harddrive.

86

General / main.cpp file suddenly empty but still has file size 29kb

« on: August 10, 2012, 08:25:31 am »

Hi. It was quite some time i did any programming but i decided to test my small game, which holds pretty much all my programming skills and the collision type i came up with etc. It's almost all that i've done so it sucks to have it disappear. I even saved the project on a USB and in my computer, but the main.cpp is empty in both places. I have a few other smaller test programs with 5-8 kb main.cpp files and they work fine. But in this only important project it's gone.

The file was last changed 03/17 it says, i'm not sure if i did any programming then or not. What gives me a bit of hope still is that it's 29kb, so it can't be empty. Does anyone know what i can do? I'll post the file here so you can check for yourselves.



[attachment deleted by admin]

87

General / homing missile

« on: August 09, 2011, 12:29:12 pm »

Thanks for your reply. I could not get it to work though since i didn't fully understand it. However i managed to get it to work with my atan angles by  using a different formula to check for angles depending on if the missile rotation is above or below 0.

Code: [Select]

Missile.SetPosition(Missile.GetPosition().x + sin(missile.worldAngle)*2, Missile.GetPosition().y + cos(missile.worldAngle)*2);

if (missile.atanAngle < 0){
    if (missile.toTargetAngle - missile.atanAngle > 0 && missile.toTargetAngle - missile.atanAngle < PI)
        missile.rotation  -= 2;
        else
            missile.rotation += 2;
}
if (missile.atanAngle >= 0){
    if (missile.toTargetAngle - missile.atanAngle < 0 && missile.toTargetAngle - missile.atanAngle > -PI)
        missile.rotation  += 2;
        else
            missile.rotation  -= 2;
}

This checks for the certain distances between the angles, different ones above 0 and below 0, and decides which direction to go based on that. The key here is that i have to check below 0 and above 0 which formula to use.

And it works perfectly no matter where i put my mouse it will choose the shortest turning path.

However i barely understand myself what i did, maybe someone could explain it better .

Edit: Ok well i do kinda understand what i'm doing but it's hard to explain. I change direction depending on if the angle is over or under 180 degrees, and i need a different formula depending on if i am below or above 0, and there's a bit more to it by that. But i was mostly testing alot and getting lucky.

88

General / homing missile

« on: August 08, 2011, 10:01:35 pm »

Hi. I'm attempting to make a homing missile, and i managed to get it work quite well except for one thing. So far i have only done the rotation of the missile but the problem is that since i am using atan2 to check for the angle of the missile to the target, when the transition comes from 3.14 to -3.14 the missile will start rotating the other way.

Code: [Select]

missile.targetVectorX = mouseX - Missile.GetPosition().x;
missile.targetVectorY = mouseY - Missile.GetPosition().y;

missile.worldAngle = Missile.GetRotation() * PI / 180;
missile.atanAngle = atan2(cos(missile.worldAngle), sin(missile.worldAngle));
missile.distanceToTarget = sqrt(missile.targetVectorX * missile.targetVectorX + missile.targetVectorY * missile.targetVectorY);
missile.toTargetAngle = atan2(missile.targetVectorY, missile.targetVectorX);
if (missile.atanAngle < missile.toTargetAngle)
    missile.rotation  -= 1;
else
missile.rotation += 1;

Missile.SetRotation(missile.rotation);

Any ideas? maybe a possibility to get a radian 6.28 no minus instead of atan2 on the toTargetAngle?

Thx.

89

General / Rotation Formula

« on: August 08, 2011, 04:53:18 am »

Ok i managed to change the start position to either left / right / top / bottom by switching the sin, cos and the minus and plus. Now the only problem is that it doesn't update position when it should.

This is the code of the setposition.

Code: [Select]

Door.SetPosition(Room.GetPosition().x + cos(bodyAngle)*Room.GetSize().x/2, Room.GetPosition().y - sin(bodyAngle)*Room.GetSize().x/2);

Edit: My bad. Was using int for the bodyAngle :oops:. Also i was able to change the starting position of the door by adding for example -90 here:

Code: [Select]

double bodyAngle = (Room.GetRotation() - 90) * PI / 180; Thanks alot for your help, i learned something new now that will certainly help alot.

90

General / Rotation Formula

« on: August 08, 2011, 02:12:39 am »

thx again for a quick reply. I checked out that link and now know better how it works. cos and sin is to take the length and angle (which we know), and add the position in x and y. Anyway i made it work in my code, but not the way i wanted. I noticed that the "satellite" which is my "door" in my example wants to spawn at the center of the x and at the top / bottom of y. That means i can't put the door at the right or left. My other object is rectangular so the door can only go on the long sides. I will try to think for myself if i can correct this.

Another thing that was weird was that the position of the door would only update 7 times on a full lap around the circle independant of speed. The rotation of the door and the room would update on every frame though.