collision detection problem solved!

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!

Code:

---

        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.

Code:

---

                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;
                }       
        }

---

Still using numeric constants like 70, I see.

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

Code:

---

if (l2<-0)

---

is that supposed to be l2 <= 0?

Edit:

Code:

---

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:

Code:

---

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