Ellipse collision tests only work with circles

[parasyte]

The collision tests for ellipse assume that the ellipse is a perfect circle, e.g. that its radius is uniform in every direction. Ellipses are allowed stretch over the X and Y axes, turning it into an oval. me.Ellipse has some properties for handling this:

• radius is the maximum radius
• scaleV is a unit vector representing the ratio between the maximum radius and the x,y axes.
• radiusV is a pre-scaled vector representing the actual radius along the x and y axes.

The SAT collision tests currently only use radius, which is fine for circles. To support scaled ellipses, the radius must be scaled by scaleV and the cos and sin for the angle between the ellipses. The angle is determined using atan2.

[obiot]

one small note : as a prior simple AABB collision check is done using the ellipse bounding box, "only" the collision response won't be fully accurate.

[obiot]

I really loved the idea in this post answer :
http://gamedev.stackexchange.com/questions/12836/ellipsoid-v-box-collision-detection

Instead of solving the collision between the ellipse and a polygon, it might be easier to calculate the inverse transformation matrix, that transforms the ellipse to a circle, and transform the polygon too using that matrix, then we can make a simple (already working) circle to polygon collision tests :)

Few comments :

• most difficult part is probably how to calculate the transformation matrix from a polygon shape to a circle one
• this might not be the most efficient way, as it might creates a lots of temporary object

[obiot]

same here -> 3.1.0

[parasyte]

@obiot Did you really mean to close this ticket?

[obiot]

yes, i tried to clean up some tickets, and I created one with all the ellipse limitations, see #809, that refers to this one