如何检测pygame中的碰撞？

Question

I am making an asteroids space shooter style game and I can't work out how to do collisions between my bullets and the asteroids/aliens and of course the ship.

I tried checking positions but my method was overly complicated, lagged the game, and didn't actually work at all.

My attempt:

        for missile in missiles:
            for asteroid in asteroids:
                if missiles[missile][0] > asteroids[asteroid][0] or missiles[missile][0] + 20 < asteroids[asteroid][0] + 70:
                    # remove missile and asteroid

Say I have an asteroid and a ship and also a bullet I want it so that when asteroid and bullet collide they both are destroyed and the ship isn't, but when asteroid and ship collide they are both destroyed.

Answer 1

Collision checks check for overlaps on the horizontal or vertical positions:

if obj1.y + obj1.radius > obj2.y - obj2.radius

if obj1.y - obj1.radius < obj2.y - obj2.radius

Do the same for the x direction, but remember that the directions are flipped in terms of in which direction the pixels go up

Answer 2

PyGame already provides collision detection between Sprites. The collision detection handed off to some C code and is highly optimized. You shouldn't attempt to re-evaluate collision calculations within Python as it certainly won't be as fast as PyGame's native solution and it is introducing the opportunity for new bugs.

Review the documentation here: https://www.pygame.org/docs/ref/sprite.html

It will provide information on how to implement proper collision detection between sprites.

For your given example, I am assuming that your individual missiles and astroids are both Sprites within PyGame.

Then I am assuming that the individual missiles and astroids are in Sprite Groups called 'missiles' and 'astroids'.

If that is true, you could simply do the following:

pygame.sprite.groupcollide(missiles, astroids, true, true)

This will check for collisions between the missiles and astroids and kill/destroy any of sprites for which a collision is detected. You can also provide a custom collision calculation function to determine the collisions if your sprites don't have a 'rect' value.