Sphere to sphere collision
Hi all;
I''m trying to get the first time ( not the closest point) that two spheres touch each other, where dist = 2*r. I tried to do that modifying the code from Oleg Dopertchouk, at gamedev, but i failed.
Does anybody knows how to do that?
Here is the code i was trying to change (Oleg Dopertchouk)
BOOL bSphereTest(CObject3D* obj1, CObject3D* obj2 )
{
// Relative velocity
D3DVECTOR dv = obj2->prVelocity - obj1->prVelocity;
// Relative position
D3DVECTOR dp = obj2->prPosition - obj1->prPosition;
//Minimal distance squared
float r = obj1->fRadius + obj2->fRadius;
//dP^2-r^2
float pp = dp.x * dp.x + dp.y * dp.y + dp.z * dp.z - r*r;
//(1)Check if the spheres are already intersecting
if ( pp < 0 ) return true;
//dP*dV
float pv = dp.x * dv.x + dp.y * dv.y + dp.z * dv.z;
//(2)Check if the spheres are moving away from each other
if ( pv >= 0 ) return false;
//dV^2
float vv = dv.x * dv.x + dv.y * dv.y + dv.z * dv.z;
//(3)Check if the spheres can intersect within 1 frame
if ( (pv + vv) <= 0 && (vv + 2 * pv + pp) >= 0 ) return false;
//Discriminant/4
float D = pv * pv - pp * vv;
return ( D > 0 );
}
Try something like that; it works for me
good luck,
David
...{ float dt = 1.0f / UPDATE_FPS; // UPDATE_FPS == 60 Vector Vp = obj1->GetLinVelocity(); Vector Vq = obj2->GetLinVelocity();#define sign(n) (n >= 0.0f ? 1.0f : -1.0f) Vector Vab = Vp - Vq; Vector l = m_Position - Sphere.m_Position; float aa = Vab * Vab; float bb = 2.0f * (l * Vab*dt) * dt; float cc = l * l - (m_Radius + Sphere.m_Radius) * (m_Radius + Sphere.m_Radius); float q = -0.5f * bb + sign(bb) * sqrt(bb * bb - 4 * aa * cc)); float t0 = q / aa; if (t0 < 0.0f || t0 > 1.0f) return 0; if (t0 > dt) t0 = dt;}
good luck,
David
ok...i use the algorithm above but i have a problem...may i normalize position before use it???
i''m working with Coluna in the game...so i''m using the same post.
i''m working with Coluna in the game...so i''m using the same post.
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