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Help => Window => Topic started by: dotty on February 20, 2012, 05:13:20 pm

Title: Moving a shape along both axis using sf::Vector2f
Post by: dotty on February 20, 2012, 05:13:20 pm

Hello, I read here a couple of days ago about using a Vector2f to process my movement, this seemed an obvious thing once I read it. However, I'm getting a little confused by it.

I have an Update() method which gets run every frame, I also have a ManageInput() method as well, which also get's run every frame.

The Update() method also runs this code

Code: [Select]


this->shape.Move( this->velocity );


this->velocity is obviously the Vector2f in question. The ManageInput() method is just a series of IF statements checking for W,A,S and D keyPresses. Here's a sample of this code

Code: [Select]


if (sf::Keyboard::IsKeyPressed( sf::Keyboard::W )) {
this->velocity = sf::Vector2f(0, -1) * this->deltatime;
}

if (sf::Keyboard::IsKeyPressed( sf::Keyboard::S )) {
this->velocity = sf::Vector2f(0, 1) * this->deltatime;
}

if (sf::Keyboard::IsKeyPressed( sf::Keyboard::A )) {
this->velocity = sf::Vector2f(-1, 0) * this->deltatime;
}

if (sf::Keyboard::IsKeyPressed( sf::Keyboard::D )) {
this->velocity = sf::Vector2f(1, 0) * this->deltatime;
}


However, using this code I can only move along 1 axis at a time.

If I modify this code to look like this

Code: [Select]


if (sf::Keyboard::IsKeyPressed( sf::Keyboard::W )) {
this->shape.Move(sf::Vector2f(0, -1)) * this->deltatime;
}

if (sf::Keyboard::IsKeyPressed( sf::Keyboard::S )) {
this->shape.Move(sf::Vector2f(0, 1)) * this->deltatime;
}

if (sf::Keyboard::IsKeyPressed( sf::Keyboard::A )) {
this->shape.Move(sf::Vector2f(-1, 0)) * this->deltatime;
}

if (sf::Keyboard::IsKeyPressed( sf::Keyboard::D )) {
this->shape.Move(sf::Vector2f(1, 0)) * this->deltatime;
}


It works as expected, allows me to both on both axis. How would I modify the top code to work as I want it to.

Title: Moving a shape along both axis using sf::Vector2f
Post by: Elgan on February 20, 2012, 05:29:16 pm

try

Code: [Select]


if (sf::Keyboard::IsKeyPressed( sf::Keyboard::W )) {
      this->velocity += ( sf::Vector2f(0, -1) * this->deltatime );
   }

   if (sf::Keyboard::IsKeyPressed( sf::Keyboard::S )) {
      this->velocity += sf::Vector2f(0, 1) * this->deltatime;
   }

if (sf::Keyboard::IsKeyPressed( sf::Keyboard::A )) {
      this->velocity += sf::Vector2f(-1, 0) * this->deltatime;
   }

   if (sf::Keyboard::IsKeyPressed( sf::Keyboard::D )) {
      this->velocity += sf::Vector2f(1, 0) * this->deltatime;
   }

Title: Moving a shape along both axis using sf::Vector2f
Post by: kamui on February 20, 2012, 05:29:41 pm

Hello,

this because you're using sf::Events instead of sf::Input (if you're on SFM-1.6).

Read this Tutorial  (http://www.sfml-dev.org/tutorials/1.6/window-events.php)for more explanations.

Edit : oops, sorry  :D did'nt wrote until the end... Elgan is right ;) (you delete your first assignement with both "=" operations).

Title: Moving a shape along both axis using sf::Vector2f
Post by: Laurent on February 20, 2012, 05:31:25 pm

Code: [Select]

if (sf::Keyboard::IsKeyPressed( sf::Keyboard::W )) {
      this->velocity.y -= this->deltatime;
   }

   if (sf::Keyboard::IsKeyPressed( sf::Keyboard::S )) {
      this->velocity.y += this->deltatime;
   }

if (sf::Keyboard::IsKeyPressed( sf::Keyboard::A )) {
      this->velocity.x -= this->deltatime;
   }

   if (sf::Keyboard::IsKeyPressed( sf::Keyboard::D )) {
      this->velocity.x += this->deltatime;
   }