collision detection problem solved!

[Shamino]

I decided to go back to the roots of where all this came from, with all the trigonometry and calculus and whatnot.

I decided to add a few structs to help my cause, ray and plane.

I learned that a ray is nothing but a point origin and basically another point which is found by subtracting point a from b.

I learned that I actually need the dot product of that specific ray's directional vector.

Among other numerous vector math stuff.

I applied my knowledge and came up with this:

Perfect!

	bool planeCollision2d(plane & boundingPlane, vector2 & objectPosition)
	{
		ray line_between_objects(objectPosition,boundingPlane.position);
		double DotProduct=line_between_objects.direction.dot_product(boundingPlane.normal);
		double l2;

		//determine if ray paralle to plane
		if ((DotProduct<0)&&(DotProduct>-0)) 
			return false;

		l2=(boundingPlane.normal.dot_product(boundingPlane.position-objectPosition))/DotProduct;

		if (l2<-0) 
			return false;

		return true;
	}

Ahhh the beauty and simplicity of pong logic.

		if(ball->getVelocity().x > 0)
		{
			if (collision2d(ball->getMinimum(), ball->getMaximum(), player2->paddle->getMinimum(), player2->paddle->getMaximum()))
			{
				reverse_x_velocity(ball->getVelocity());
			}
			else if(planeCollision2d(right, ball->getLocation()))
			{
				reverse_x_velocity(ball->getVelocity());
				ball->getLocation().x = 0;
				ball->getLocation().y = 0;
				player1->goal();
			}
		}
		if(ball->getVelocity().x < 0)
		{

			if (collision2d(ball->getMinimum(), ball->getMaximum(), player1->paddle->getMinimum(), player1->paddle->getMaximum()))
			{
				reverse_x_velocity(ball->getVelocity());
			}
			else if(planeCollision2d(left, ball->getLocation()))
			{
				reverse_x_velocity(ball->getVelocity());
				ball->getLocation().x = 0;
				ball->getLocation().y = 0;
				player2->goal();
			}
		}
		if(ball->getVelocity().y > 0)
		{
			if (planeCollision2d(top, ball->getLocation()))
			{
				reverse_y_velocity(ball->getVelocity());
			}
		}
		if(ball->getVelocity().y < 0)
		{
			if (planeCollision2d(bottom, ball->getLocation()))
			{
				reverse_y_velocity(ball->getVelocity());
			}
		}
	}
	void check_paddle_collision()
	{	
		if (planeCollision2d(top, player1->paddle->getLocation()))
		{
			player1->paddle->getLocation().y = 70;
		}
		else if(planeCollision2d(bottom, player1->paddle->getLocation()))
		{
			player1->paddle->getLocation().y = -70;
		}
		if (planeCollision2d(top, player2->paddle->getLocation()))
		{
			player2->paddle->getLocation().y = 70;
		}
		else if(planeCollision2d(bottom, player2->paddle->getLocation()))
		{
			player2->paddle->getLocation().y = -70;
		}	
	}

[matsp]

Still using numeric constants like 70, I see.

Also, try to avoid calling variables things that look like numbers, such as l2.

if (l2<-0)

is that supposed to be l2 <= 0?

Edit:

reverse_x_velocity(ball->getVelocity());

Do I take it that getVelocity returns a reference to Ball::velocity? If so, perhaps you should do something like this instead:

ball->setVelocity(-ball->getVelocity().x, ball->getVelocity().y);

That maintains strict encapsulation.
Or you could let the velocity itself have a public member function "reversex()" and "reversey()".

--
Mats

--
Mats