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AABB collision detection

Started by
17 comments, last by JoeJ 2 years, 6 months ago

well I think I am having a problem accessing my class

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Just knock at the door

pbivens67 said:
well I think I am having a problem accessing my class

That's plenty of information to receive help ; )
Maybe this causes issues:

class paddle
{
// ...
}paddle;

Class and the global object have the same name. Again i wonder this compiles, and now idea if you could create a second paddle object after that.
One common way to avoid this is using differing upper / lower cases:

class Paddle
{
// ...
}paddle;

@pbivens67 So what is BallX when BallY becomes -100? I am assuming the paddle doesn't move.

I'd suggest putting a break point(s) on the IF statement(s) and see where it fails.

if (X_dist*X_dist <= width * width)

If (Y_dist*Y_dist <= height * height))

//Collision detected

I seem to be having problems accessing the classes, when I run this code it outputs only the same output regardless of where the ball is.

float move_paddle = 0.0f;
float ball_x = 0.0f, ball_y = 0.0f;
float xstep = 2.5f, ystep = 2.5f;

class Paddle
{
public:
	float p_x = -20.0f + move_paddle;
	float p_y = -100.0f;
	float p_width=40.0f;
	float p_height=15.0f;
}paddle;

class Ball
{
public:
	float b_x = -2.5f + ball_x; 
	float b_y = -2.5f + ball_y;
	float b_width=5.0f;
	float b_height=5.0f;
}ball;

class Brick
{
public:
	float x;
	float y;
	float x_width = 35;
	float y_height = 15;
	float x_right;
	float y_top;
	Brick(float br_x_left, float br_y_bottom, float br_x_right, float br_y_top)
	{
		x = br_x_left;
		y = br_y_bottom;
		x_right = br_x_right;
		y_top = br_y_top;
	}
};

void Timer(int v)
{
	if (ball_x >= 145.0f || ball_x <= -135.0f)
	{
		xstep = -xstep;
	}
	if (ball_y >= 100.0f || ball_y <= -100.0f)
	{
		ystep = -ystep;
	}
	ball_x += xstep;
	ball_y += ystep;
	glutPostRedisplay();
	glutTimerFunc(50, Timer, 0);
}

void collision()
{
	float X_dist = (ball.b_x - paddle.p_x);
	float Y_dist = (ball.b_y - paddle.p_y);
	float width = (paddle.p_width / 2.0 + ball.b_width / 2.0);
	float height = (paddle.p_height / 2.0 + ball.b_height / 2.0);

	cout << "Xdist: " << X_dist << "   width: " << width << "   Ydist: " << Y_dist << "   height: " << height << endl;

	if ((X_dist*X_dist <= width * width) && (Y_dist*Y_dist <= height * height))
	{
		cout << "Collision Detected" << endl;
	}
}

pbivens67 said:
ball_x += xstep; ball_y += ystep;

There you change the global variables, but you forgot to change the members of the ball class.
As said - to avoid such confusion, use only the class. Remove the global variables ball_x/y.

I tried removing the global variables but it does not compile

um… read compiler error messages, realize the mistake, fix it?

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