public final boolean intersect(Ray ray) {
float dx = _ps.get_position().getX() - ray.get_origin().getX();
float dy = _ps.get_position().getY() - ray.get_origin().getY();
float dz = _ps.get_position().getZ() - ray.get_origin().getZ();
float v = Vector3.dot(ray.get_direction(), new Vector3(dx, dy, dz));
// Do the following quick check to see if there is even a chance
// that an intersection here might be closer than a previous one
if (v -_radius > ray.getT())
return false;
// Test if the ray actually intersects the sphere
double t = this._radSqr + v*v - dx*dx - dy*dy - dz*dz;
if (t < 0)
return false;
// Test if the intersection is in the positive
// ray direction and it is the closest so far
t = v - ((float) Math.sqrt(t));
System.out.println("hum"+ t);
if ((t > ray.getT()) || (t < 0))
return false;
ray.setT((float)t);
// ray._asterHit= this;
return true;
}
Ray Intersection
Author
Well I found a piece of code, that proccesses ray to sphere intersection. But I am not sure I understand it completely.
I have tested it with a ray that has origin in 0 and direction (1,0,0). The sphere (_bs) has a position of (5,0,0) and a radious of 1.5.
With this setup it fails at test 3. Wich I dont see why it should. What am I doing wrong?...
im too lazy to completely check your code, but this is what i use for sphere intersection:
if the ray is infinite it means it is checked for t=0..infinity, non infinite means a linesegment from t=0..1, usefull for shadowrays for example.
the rest should all be pretty obvious.
note how i used my l33t math skills to remove all sqrts [grin]
public bit SolidHitTrace(Ray ray){ //relative distance ray.pos.x = Void.World.Position.x - ray.pos.x; ray.pos.y = Void.World.Position.y - ray.pos.y; ray.pos.z = Void.World.Position.z - ray.pos.z; //sphere check float A, B, C, D; A = (ray.dir.x*ray.dir.x + ray.dir.y*ray.dir.y + ray.dir.z*ray.dir.z); B = (ray.pos.x*ray.dir.x + ray.pos.y*ray.dir.y + ray.pos.z*ray.dir.z) * 2; C = (ray.pos.x*ray.pos.x + ray.pos.y*ray.pos.y + ray.pos.z*ray.pos.z) - (Radius*Radius); D = (B*B) - (4*A*C); if (D >= 0){ if (ray.infinite){ if ((B * fabs(B) + D > 0)) return true; }else{ C = B - 2 * A; //if not behind ray && not too far away if ((B * fabs(B) + D > 0) && (C * fabs(C) - D < 0)) return true; } } return false; }if the ray is infinite it means it is checked for t=0..infinity, non infinite means a linesegment from t=0..1, usefull for shadowrays for example.
the rest should all be pretty obvious.
note how i used my l33t math skills to remove all sqrts [grin]
Author
cool stuff
I want to
1) Either check with an infinite ray and get the point on the ray where it intersects with the sphere
2)use a limited ray and get the point of intersection?.. can I do that?
I want to
1) Either check with an infinite ray and get the point on the ray where it intersects with the sphere
2)use a limited ray and get the point of intersection?.. can I do that?
I'm using
clean and readable :).I prefer not to pass two parameters if i can just pass their difference.
//// Ray-sphere intersection routine. // p=(ray origin position - sphere position),// d=ray direction,// r=sphere radius,// i1=first intersection distance,// i2=second intersection distance// i1<=i2// i1>=0// returns true if intersection found,false otherwise.// bool RaySphereIntersect(const Vec3d &p, const Vec3d &d,real64 r, real64 &i1, real64 &i2){ real64 det,b; b = -DotProd(p,d); det=(b*b) - (p.x*p.x + p.y*p.y + p.z*p.z) + r*r; if (det<0){ return false; }//else det= sqrt(det); i1= b - det; i2= b + det; // intersecting with ray? if(i2<0) return false; if(i1<0)i1=0; return true;};clean and readable :).I prefer not to pass two parameters if i can just pass their difference.
Author
Ah so first and second intersection distance is the ray punching through the sphere in both sided?
yes,exactly :) Also it returns zero for first intersection if you're inside sphere. I really used both results :)
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