Best ways to test for collision detection.
If you want a working implementation of a collision detection system to see what you would like, try Paul Nettle''s ellipsoid collision scheme.
http://www.fluidstudios.com/publications.html
That seems to be very effective. Spheres are easier to implement though.
http://www.fluidstudios.com/publications.html
That seems to be very effective. Spheres are easier to implement though.
Just use the distance equation,
Private Function GetDist(intX1 As Single, intY1 As Single, intX2 As Single, intY2 As Single) As Single
DIST = Sqr((intX1 - intX2) ^ 2 + (intY1 - intY2) ^ 2)
End Function
Private Sub Colision()
If Dist(Object1, Ojbect2) >= 0 Then
'' perform collision repsonse code
Else
Exit Sub
End If
If you are using 3D, the dist equation is
Sqr((intX1 - intX2) ^ 2 + (intY1 - intY2) ^ 2) + (intZ1 - intZ2) ^ 2)
-megaman
Private Function GetDist(intX1 As Single, intY1 As Single, intX2 As Single, intY2 As Single) As Single
DIST = Sqr((intX1 - intX2) ^ 2 + (intY1 - intY2) ^ 2)
End Function
Private Sub Colision()
If Dist(Object1, Ojbect2) >= 0 Then
'' perform collision repsonse code
Else
Exit Sub
End If
If you are using 3D, the dist equation is
Sqr((intX1 - intX2) ^ 2 + (intY1 - intY2) ^ 2) + (intZ1 - intZ2) ^ 2)
-megaman
Two problems with distance equasion technique: a) works only if you''re testing if two points collide. Might be better if you could check for a range. That would give you a point within a sphere test, which is a little better. b) it''s slow. You''ve got 2 multiplications two substractions and a square root. For normal loads that''s probably fine, but not when you''ve got a good deal of collidable objects on screen.
A simple InRect call is fine for a simple 2D engine, especially if your sprites take up an entire rect. This can be most simply implemented as (in C):
Also, if you''re working with a tile engine with unmovable tiles, flaging tiles you can''t walk on is a simple check. e.g. map[x][y].isWalkable
A simple InRect call is fine for a simple 2D engine, especially if your sprites take up an entire rect. This can be most simply implemented as (in C):
inline bool IsInRect(int x, int y, RECT rect){ return x > rect.left && x < rect.right && y > rect.top && y < rect.bottom;} Also, if you''re working with a tile engine with unmovable tiles, flaging tiles you can''t walk on is a simple check. e.g. map[x][y].isWalkable
Author
inline bool IsInRect(int x, int y, RECT rect)
{ return x > rect.left && x < rect.right && y > rect.top && y < rect.bottom;
}
is somthing i never seen before quite intersting
{ return x > rect.left && x < rect.right && y > rect.top && y < rect.bottom;
}
is somthing i never seen before quite intersting
Most engines when you collide with a wall at an angle you move slowly parralel to the wall. If you get what i mean - in my engine you stop dead - i wanted to have that slow parralel movement - what algoritm is that.
YOU''''LL NEVER BEAT THE IRISH!
YOU''''LL NEVER BEAT THE IRISH!
quote:Original post by Cuchulainn
Most engines when you collide with a wall at an angle you move slowly parralel to the wall. If you get what i mean - in my engine you stop dead - i wanted to have that slow parralel movement - what algoritm is that.
Just project the velocity vector onto the surface. My linear algebra is a bit rusty bit I think it''s:
v is the velocity vector, w1 and w2 are any two non-parallel vectors on the plane. The projection of v onto the plane is (v dot w1)/(w1 dot w1)*w1 + (v dot w2)/(w2 dot w2)*w2
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