Messages

1

General / Re: Rectangle bottom collision issues

« on: February 06, 2022, 05:25:01 pm »

Thank you for your reply, i'll check it out.

2

General / Rectangle bottom collision issues

« on: February 06, 2022, 03:40:32 pm »

Hello everyone, I have a problem with bottom collision detection in my project.


I have a function that checks if the bottom of the character collides with a platform, it almost work as wanted, but there is a problem, actually it works only with some platforms but will fail with others.

See the screens below.


Working :


Not working :


On the first screenshot, we can see the collisions fits perfectly, but in the second screen the character is overlapping the platform.


Here's the code for bottom collision detection :

bool Character::isBottomColliding(Platform *platforms)
{
   int i;
   sf::FloatRect characterRect;
   sf::FloatRect platformRect;
   characterRect = getRect();
   for(i = 0; i < LEVEL_MAX_PLATFORMS; i++)
   {
      platformRect = platforms[i].getRect();
      if(characterRect.left + characterRect.width >= platformRect.left && characterRect.left <= platformRect.left + platformRect.width && characterRect.top + characterRect.height >= platformRect.top)
      {
         isGrounded = true;
         isJumping = false;
         return true;
      }  
   }
   return false;  
}

The update function :

void update(Level *level, Character *character)
{
   if(character->falling() && !character->isBottomColliding(level->getPlatforms()))
   {
      character->fall(); //This function is moving character down to simulate gravity
   }
   character->move();
}

I don't understand why it works with the first platforms but not with the other one.


Sorry if my english was bad, this is not my native language.


EDIT : It works fine when gravity is set to 1

void Character::fall()
{
   sprite.setPosition(getRect().left, getRect().top + gravity);
   isFalling = true;
   isGrounded = false;  
}

EDIT 2: I found that when the platform's Y position modulus (%) the gravity equals 0, there is no problem

if platformRect.top % gravity == 0 ==> No collision problems







 

3

Graphics / Re: Collision accuracy issues

« on: April 08, 2020, 01:03:32 am »

Thank you for your detailed answer.

Running the update loop faster than the frame rate and multiplying the direction vector by delta time finally solved my problem.

Have a nice day/night !

4

Graphics / Re: Collision accuracy issues

« on: April 07, 2020, 11:20:38 pm »

Thank you for you answer.

I followed your advice, and moved the blockDirection vector's y component down after collision is detected.

Here's what i've added to my code :

Code: [Select]


//After collision has been checked
gameBlock.moveBlock(sf::Vector2f(blockDirection.x, -blockDirection.y));

The result is illustrated in the picture below :




So now, the projectile isn't going too far, but not far enough, it is stoped before "real" collision.
This means I have to find the right value to move down the block.

I keep searching for it.

5

Graphics / [SOLVED] Collision accuracy issues

« on: April 07, 2020, 07:34:20 pm »

Hello everyone, I am currently creating a "Bubble Shooter" like (see https://bubble-shooter.co/) only with RectangleShapes but I am facing a problem with collision accuracy. In fact, the collision is well detected, but not accurate.

See these images :

https://ibb.co/F0sckGd

https://ibb.co/MPYMWw5

As you can see, collision isn't accurate.

What i've found so far :

    Increasing Framerate limit (setFramerateLimit) to something like 600 and decreasing the move speed to 1 fix this issue.
    I'm quite new to game development, but I guess that running a game at 600 fps isn't a good idea right ?

It looks like the issue is related to the speed and the direction vector, but cannot find out what's wrong.

Here's some part of my source code.

void Game::processEvent(sf::Event e)
{
   if(e.type == sf::Event::MouseButtonPressed && canShoot == true)
   {
      float mouseX = sf::Mouse::getPosition(gameWindow).x; //Getting mouse position
      float mouseY = sf::Mouse::getPosition(gameWindow).y;

      if(mouseY < gameSize.y - blockSize.y)
      {
         blockDirection.x += mouseX - (gameSize.x / 2); //Calculating direction vector (gameSize.x / 2) is the x origin of the projectile.
         blockDirection.y += mouseY - (gameSize.y - blockSize.y); //gameSize.y - blockSize.y is the y origin of the projectile
         canShoot = false;
      }
   }
}
void Game::gameUpdate()
{
   int id = isGameBlockColliding();
   if(id == -1 && canShoot == false)
   {
      blockDirection = normalizeDirection() * blockSpeed; //When blockSpeed is set to 1, there's no collision issue, but the game is much too slow.
      gameBlock.moveBlock(blockDirection);
   }
   else if(id == -2) //In case we collide with screen borders (only x axis for now)
   {
      blockDirection.x = -blockDirection.x;
      gameBlock.moveBlock(blockDirection);
   }
   else
   {
      if(canShoot == false)
      {
         canShoot = true;
         staticGameBlocks.push_back(gameBlock);
         if(gameBlock.getBlockColorID() == staticGameBlocks[id].getBlockColorID())
         {
            staticGameBlocks.erase(staticGameBlocks.begin() + id);
            staticGameBlocks.pop_back();  
         }
         spawnRandomBlock();
      }
   }
}
sf::Vector2f Game::normalizeDirection() //found this method somewhere in the forums
{
   float modulus = sqrt((blockDirection.x * blockDirection.x) + (blockDirection.y * blockDirection.y));
   if(modulus != 0)
   {
      return sf::Vector2f(blockDirection.x / modulus, blockDirection.y / modulus);
   }
   else
   {
      return blockDirection;
   }
}
int Game::isGameBlockColliding()
{
   if(!(gameBlock.getBlockPosition().left + gameBlock.getBlockPosition().width < gameSize.x && gameBlock.getBlockPosition().left > 0))
   {
      return -2;
   }
   for(int i = 0; i < staticGameBlocks.size(); i++)
   {
      sf::FloatRect staticRect = staticGameBlocks[i].getBlockPosition();
      sf::FloatRect gameBlockRect = gameBlock.getBlockPosition();
      if(staticRect.intersects(gameBlockRect))
      {
         return i;
      }
   }
   return -1;
}
 

Please let me know if you need more informations in order to help me.
Thank you in advance for any response.

(Sorry if my english was bad.)