/// <summary>
/// Determines whether there is an intersection between a <see cref="SharpDX.Ray"/> and a <see cref="SharpDX.BoundingSphere"/>.
/// </summary>
/// <param name="ray">The ray to test.</param>
/// <param name="sphere">The sphere to test.</param>
/// <param name="point">When the method completes, contains the point of intersection,
/// or <see cref="SharpDX.Vector3.Zero"/> if there was no intersection.</param>
/// <returns>Whether the two objects intersected.</returns>
public static bool Intersect(ref Ray ray, ref Vector3 centerSphere,float radius,ref Matrix4 matrix, out Vector3 point)
{
float distance;
if (!Intersect(ref ray, ref centerSphere, radius,ref matrix, out distance))
{
point = Vector3.Zero;
return false;
}
point = ray.origin + (ray.direction * distance);
return true;
}
public bool Intersect(ref Ray ray, ref Matrix4 matrix)
{
var max=Vector3.TransformPosition(Max,matrix);
var min=Vector3.TransformPosition(Min,matrix);
//first test if start in box
if (ray.origin.X >= min.X
&& ray.origin.X <= max.X
&& ray.origin.Y >= min.Y
&& ray.origin.Y <= max.Y
&& ray.origin.Z >= min.Z
&& ray.origin.Z <= max.Z)
return true;// here we concidere cube is full and origine is in cube so intersect at origine
//Second we check each face
Vector3 maxT = new Vector3(-1.0f);
//Vector3 minT = new Vector3(-1.0f);
//calcul intersection with each faces
if (ray.origin.X < min.X && ray.direction.X != 0.0f)
maxT.X = (min.X - ray.origin.X) / ray.direction.X;
else if (ray.origin.X > max.X && ray.direction.X != 0.0f)
maxT.X = (max.X - ray.origin.X) / ray.direction.X;
if (ray.origin.Y < min.Y && ray.direction.Y != 0.0f)
maxT.Y = (min.Y - ray.origin.Y) / ray.direction.Y;
else if (ray.origin.Y > max.Y && ray.direction.Y != 0.0f)
maxT.Y = (max.Y - ray.origin.Y) / ray.direction.Y;
if (ray.origin.Z < min.Z && ray.direction.Z != 0.0f)
maxT.Z = (min.Z - ray.origin.Z) / ray.direction.Z;
else if (ray.origin.Z > max.Z && ray.direction.Z != 0.0f)
maxT.Z = (max.Z - ray.origin.Z) / ray.direction.Z;
//get the maximum maxT
if (maxT.X > maxT.Y && maxT.X > maxT.Z)
{
if (maxT.X < 0.0f)
return false;// ray go on opposite of face
//coordonate of hit point of face of cube
float coord = ray.origin.Z + maxT.X * ray.direction.Z;
// if hit point coord ( intersect face with ray) is out of other plane coord it miss
if (coord < min.Z || coord > max.Z)
return false;
coord = ray.origin.Y + maxT.X *ray.direction.Y;
if (coord < min.Y || coord > max.Y)
return false;
return true;
}
if (maxT.Y > maxT.X && maxT.Y > maxT.Z)
{
if (maxT.Y < 0.0f)
return false;// ray go on opposite of face
//coordonate of hit point of face of cube
float coord = ray.origin.Z + maxT.Y * ray.direction.Z;
// if hit point coord ( intersect face with ray) is out of other plane coord it miss
if (coord < min.Z || coord > max.Z)
return false;
coord =ray.origin.X + maxT.Y * ray.direction.X;
if (coord < min.X || coord > max.X)
return false;
return true;
}
else //Z
{
if (maxT.Z < 0.0f)
return false;// ray go on opposite of face
//coordonate of hit point of face of cube
float coord =ray.origin.X + maxT.Z * ray.direction.X;
// if hit point coord ( intersect face with ray) is out of other plane coord it miss
if (coord < min.X || coord > max.X)
return false;
coord = ray.origin.Y + maxT.Z * ray.direction.Y;
if (coord < min.Y || coord > max.Y)
return false;
return true;
}
}
/// <summary>
/// Determines whether there is an intersection between a <see cref="SharpDX.Ray"/> and a <see cref="SharpDX.BoundingSphere"/>.
/// </summary>
/// <param name="ray">The ray to test.</param>
/// <param name="sphere">The sphere to test.</param>
/// <param name="distance">When the method completes, contains the distance of the intersection,
/// or 0 if there was no intersection.</param>
/// <returns>Whether the two objects intersected.</returns>
public static bool Intersect(ref Ray ray, ref Vector3 centerSphere,float radius,ref Matrix4 matrix, out float distance)
{
//Source: Real-Time Collision Detection by Christer Ericson
//Reference: Page 177
var center=Vector3.TransformPosition(centerSphere,matrix);
Vector3 m=ray.origin-center;
float b = Vector3.Dot(m, ray.direction);
float c = Vector3.Dot(m, m) - (radius * radius);
if (c > 0f && b > 0f)
{
distance = 0f;
return false;
}
float discriminant = b * b - c;
if (discriminant < 0f)
{
distance = 0f;
return false;
}
distance = -b - (float)Math.Sqrt(discriminant);
if (distance < 0f)
distance = 0f;
return true;
}
