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Problem with detecting walls

bstelly (1)
I am a student practicing C++ programming, and I am creating a simple 2d maze game, kind of like pac-man. I ran into a problem though. When the player hits a wall, they are able to go through it if they run into it from a certain side. For example if they run into a horizontal wall from left or right, the player goes right through the wall. If they run into a horizontal wall from top or bottom, the wall works like it's supposed to and prevents movement. The same goes for the vertical walls, except the problem occurs when a player runs into it from top to bottom.
This is my first game with graphics and I am really confused as to why my code isn't working.
Here is some of my code. Any help would be appreciated.


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void Application2D::update(float deltaTime) {
	m_timer += deltaTime;
	int iter = 0;
	Vector2 moveUp(0, (400 * deltaTime));
	Vector2 moveDown(0, (-400 * deltaTime));
	Vector2 moveLeft((-400 * deltaTime), 0);
	Vector2 moveRight((400 * deltaTime), 0);



	//Vertical Walls
	mVerticalWall[0].SetPosition(110, 105);
	mVerticalWall[1].SetPosition(150, 105);


	//Horizontal Walls
	mHorizontalWall[0].SetPosition(65, 500);
	mHorizontalWall[1].SetPosition(500, 500);
	mHorizontalWall[2].SetPosition(450, 500);
	mHorizontalWall[3].SetPosition(400, 500);
	mHorizontalWall[4].SetPosition(350, 500);



		int facingVertWall = 0;
		int facingHorzWall = 0;
		int facingVertWallCorner = 0;
		int facingHorzWallCorner = 0;
		int horzWall;
		int vertWall;
		bool hitVertWall;
		bool hitHorzWall;
		//Check for vertical wall for player
		for (int i = 0; i < 10; i++)
		{
			if ((mPlayer->GetX() + 25) >= mVerticalWall[i].GetX() &&
				(mPlayer->GetX() - 25) <= mVerticalWall[i].GetX())
			{
				if ((mPlayer->GetY() + 20) >= (mVerticalWall[i].GetY() - 50) &&
					(mPlayer->GetY() - 20) <= (mVerticalWall[i].GetY() + 50))
				{
					std::cout << "You hit a vertical wall" << std::endl;
					hitVertWall = true;
					vertWall = i;
					break;
				}
			}
			else
			{
				hitVertWall = false;
			}
		}

		//Checks for Horizontal Wall for player
		for (int i = 0; i < 10; i++)
		{
			if ((mPlayer->GetY() + 15) >= (mHorizontalWall[i].GetY() - 10) &&
				(mPlayer->GetY() - 15) <= (mHorizontalWall[i].GetY() + 10))
			{
				if ((mPlayer->GetX() + 15) >= (mHorizontalWall[i].GetX() - 50) &&
					(mPlayer->GetX() - 15) <= (mHorizontalWall[i].GetX() + 50))
				{
					std::cout << "you hit a horizontal wall" << std::endl;
					hitHorzWall = true;
					horzWall = i;
					break;
				}
			}
			else
			{
				hitHorzWall = false;
			}
		}
		if (hitVertWall == true)
		{
			if (mPlayer->GetX() <= mVerticalWall[vertWall].GetX())
			{
				facingVertWall = 1;		//Can't move RIGHT
			}
			else if (mPlayer->GetX() >= mVerticalWall[vertWall].GetX())
			{
				facingVertWall = 2;		//Can't move LEFT
			}
			if (mPlayer->GetY() <= mVerticalWall[vertWall].GetY())
			{
				facingVertWallCorner = 3;		//Can't move UP
			}
			else if (mPlayer->GetY() >= mVerticalWall[vertWall].GetY())
			{
				facingVertWallCorner = 4;		//Can't move DOWN
			}
		}

		if (hitHorzWall == true)
		{
			if (mPlayer->GetY() <= mHorizontalWall[horzWall].GetY())
			{
				facingHorzWall = 3;		//Can't move UP
			}
			else if (mPlayer->GetY() >= mHorizontalWall[horzWall].GetY())
			{
				facingHorzWall = 4;		//Can't move DOWN
			}
			if (mPlayer->GetX() == mHorizontalWall[horzWall].GetX() )
			{
				facingHorzWallCorner = 1;		//Can't move RIGHT
			}
			else if (mPlayer->GetX() == mHorizontalWall[horzWall].GetX())
			{
				facingHorzWallCorner = 2;		//Can't move LEFT
			}
		}


		aie::Input* input = aie::Input::getInstance();

		if (input->isKeyDown(aie::INPUT_KEY_W) && facingHorzWall != 3 &&
			facingVertWallCorner != 3)
			mPlayer->ChangePos(moveUp);

		if (input->isKeyDown(aie::INPUT_KEY_S) && facingHorzWall != 4 &&
			facingVertWallCorner != 4)
			mPlayer->ChangePos(moveDown);

		if (input->isKeyDown(aie::INPUT_KEY_A) && facingVertWall != 2 &&
			facingHorzWallCorner != 2)
			mPlayer->ChangePos(moveLeft);

		if (input->isKeyDown(aie::INPUT_KEY_D) && facingVertWall != 1 &&
			facingHorzWallCorner != 1)
			mPlayer->ChangePos(moveRight);

		// exit the application
		if (input->isKeyDown(aie::INPUT_KEY_ESCAPE))
			quit();

Last edited on
Golden Lizard (310)
You may want to use AABB (axis aligned bounding boxes) and have a general collision function. Something like : 
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max(x1) > min(x2) && 
max(x2) > min(x1) && 
max(y1) > min(y2) && 
max(y1) > min(y2)

Last edited on
doug4 (1535)
A wall is a wall. When you approach a "vertical" wall from the bottom, it looks like a very narrow, very deep "horizontal" wall. So, all walls must be considered both horizontal and vertical.
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