Game Maker's Garage Forum

Game Creation => Code Exchange => Topic started by: Gan on January 01, 2010, 11:21:04 PM

Title: Shape Collision Detections
Post by: Gan on January 01, 2010, 11:21:04 PM

This thread is to host code to detect collisions of different shapes such as lines, rectangles, and ovals.
This is very needed in Sc with the drawing commands as people will want to take them higher and further then ever before. It'll also become popular in Gm as Al will implement them eventually.
Now I am in search of such code/formulas and shall post them when I find/figure them out. Here is the code for collision with these shapes:
Line - Line:

Code: [Select]

Unknown

Line - Rect:

Code: [Select]

Unknown

Line - Oval:

Code: [Select]

Unknown

Rect - Rect:

Code: [Select]

Unknown

Rect - Oval:

Code: [Select]

Unknown

Oval - Oval:

Code: [Select]

Unknown

If any of you know how to get intersection/collision points of either shapes, please post!

-Gandolf

Title: Re: Shape Collision Detections
Post by: Gan on January 01, 2010, 11:38:42 PM

Whoa, check this link out:
http://www.geometrictools.com/Documentation/Documentation.html
It's as if it has everything you'll ever need to build a collision/physics/other game.


-Gandolf

Title: Re: Shape Collision Detections
Post by: Gan on February 10, 2010, 12:34:23 PM

I've figured out a fast an easy method for finding the intersection point of two lines. :)
With this I can get all kinds of collision detections between lines and line shapes such as triangles, rectangles, ect...
I can now make perfect and fast collision detection between shapes and even sprites.
Here's the formula:

Code: [Select]

//Line 1
int x1 = 10;
int y1 = 210;
int x2 = 200;
int y2 = 10;

//Line 2
int x3 = 10;
int y3 = 200;
int x4 = 200;
int y4 = 10;

//Now let us find x and y of intersection point

float x = ( (x1*y2-y1*x2)*(x3-x4) - (x1 - x2)*(x3*y4 - y3*x4) ) / ( (x1-x2)*(y3-y4)-(y1-y2)*(x3-x4) );
float y = ( (x1*y2-y1*x2)*(y3-y4) - (y1 - y2)*(x3*y4 - y3*x4) ) / ( (x1-x2)*(y3-y4)-(y1-y2)*(x3-x4) );

-Gan

Title: Re: Shape Collision Detections
Post by: WarHampster on February 10, 2010, 02:17:22 PM

So much for not being able to type :P

Title: Re: Shape Collision Detections
Post by: Gan on February 10, 2010, 03:39:06 PM

Oh, I can still type but only with my left hand.


-Gan