Re: [Algorithms] Sphere to Triangle overlap check

[Mark W. <wa...@in...>]

Zaf,

First find the distance of the sphere center from the plane. If the abs distance is greater than the radius then  there is no overlap.
You then need to find the radius of the circle of intersection with the plane which is much easier than you think. The radius of intersection is simply sqrt(sphereRadiusSqr + centerDistFromPlane). Then find the distance from the sphere center projected onto the plane to each edge. If the distance is less than the radius of intersection then there's an overlap.
To find the distance to the edge, calc edgeNormal via normalize(cross(faceNormal, edge)) then calc (projectedCenter - edgeStartVertex) dot edgeNormal.
This was all from memory and a quick scribble so hopefully it's correct :-)

Cheers,
Mark


On 28/07/2010, at 9:34 PM, Zafar Qamar <zaf...@co...> wrote:

> Hi,
> This is a very old question but I can't seem to find a good answer for it and I've searched the net for quite a while.
> 
> I need a precise way of checking if a sphere and a given triangle have _any_ overlap.
> Specifically, the case I'm struggling with is when the sphere just overlaps one of the edges.
> Also, I need to cater for when the sphere is completely inside the triangle, and vice-versa
> 
> Help please? Or a decent internet link would be much appreciated
> 
> Cheers
> Zaf
> 
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