CS 1666 www.cs.pitt.edu/~nlf4/cs1666/ Collision detection - PowerPoint PPT Presentation

CS 1666 www.cs.pitt.edu/~nlf4/cs1666/ Collision detection

Collision detection We already had to implement some basic collision detection ● in the motion example ○ I.e., to keep our square from moving out of the window ○ Checking for collisions with the boundary of the window ● Generally, games will have many objects moving around the screen, how can we check whether they've hit one another? 2

No Collision 3

No Collision 4

No Collision 5

COLLISION! 6

Colliding circles 7

Complex collisions 8

Complex collisions in action 9

Even more complex collisions 10

Really complex collisions 11

Street Fighter II Hitboxes 12

The same idea is used in 3D games 13

Back to 2D And some help from SDL ● ○ SDL_bool SDL_HasIntersection(const SDL_Rect* A, const SDL_Rect* B) ■ True if the two SDL_Rect 's intersect ■ False otherwise ○ SDL_bool SDL_IntersectRect(const SDL_Rect* A, constSDL_Rect* B, SDL_Rect* result) ■ Same returns, but will also set result to the intersection of A and B if one exists ■ result will be NULL if there is no intersection 14