public void DrawLine(Vector3 start, Vector3 end, Color color, float width = 0.025f)
{
Vector3 dir = end - start;
dir.Z = 0;
Vector3 extDir1;
Vector3 extDir2;
if (dir.LengthSquared() > 0.0001f)
{
dir.Normalize();
extDir1.X = -dir.Y;
extDir1.Y = dir.X;
extDir1.Z = 0;
extDir2 = Vector3.Cross(dir, extDir1);
}
else
{
extDir1 = Vector3.UnitX;
extDir2 = Vector3.UnitY;
}
_vertexBuffer[0] = new ColoredVertex(start + extDir1 * (width / 2), color);
_vertexBuffer[1] = new ColoredVertex(start - extDir1 * (width / 2), color);
_vertexBuffer[2] = new ColoredVertex(end + extDir1 * (width / 2), color);
_vertexBuffer[3] = new ColoredVertex(end - extDir1 * (width / 2), color);
_vertexBuffer[4] = new ColoredVertex(start + extDir2 * (width / 2), color);
_vertexBuffer[5] = new ColoredVertex(start - extDir2 * (width / 2), color);
_vertexBuffer[6] = new ColoredVertex(end + extDir2 * (width / 2), color);
_vertexBuffer[7] = new ColoredVertex(end - extDir2 * (width / 2), color);
_indexBuffer[0] = 0;
_indexBuffer[1] = 1;
_indexBuffer[2] = 2;
_indexBuffer[3] = 1;
_indexBuffer[4] = 2;
_indexBuffer[5] = 3;
_indexBuffer[6] = 4;
_indexBuffer[7] = 5;
_indexBuffer[8] = 6;
_indexBuffer[9] = 5;
_indexBuffer[10] = 6;
_indexBuffer[11] = 7;
SetDeclaration();
Device.DrawIndexedUserPrimitives(PrimitiveType.TriangleList, 0, 8, 4, _indexBuffer,
Format.Index32, _vertexBuffer, ColoredVertex.Stride);
}
/// <summary>
/// Creates a right-handed spherical billboard that rotates around a specified object position.
/// </summary>
/// <param name="objectPosition">The position of the object around which the billboard will rotate.</param>
/// <param name="cameraPosition">The position of the camera.</param>
/// <param name="cameraUpVector">The up vector of the camera.</param>
/// <param name="cameraForwardVector">The forward vector of the camera.</param>
public static Matrix BillboardLh(ref Vector3 objectPosition, ref Vector3 cameraPosition, ref Vector3 cameraUpVector, ref Vector3 cameraForwardVector)
{
var result = new Matrix();
Vector3 crossed;
Vector3 final;
Vector3 difference = cameraPosition - objectPosition;
float lengthSq = difference.LengthSquared();
if (IsZero(lengthSq))
{
difference = -cameraForwardVector;
}
else
{
difference *= (float)(1.0 / Math.Sqrt(lengthSq));
}
Vector3.Cross(ref cameraUpVector, ref difference, out crossed);
crossed.Normalize();
Vector3.Cross(ref difference, ref crossed, out final);
result.M11 = crossed.X;
result.M12 = crossed.Y;
result.M13 = crossed.Z;
result.M14 = 0.0f;
result.M21 = final.X;
result.M22 = final.Y;
result.M23 = final.Z;
result.M24 = 0.0f;
result.M31 = difference.X;
result.M32 = difference.Y;
result.M33 = difference.Z;
result.M34 = 0.0f;
result.M41 = objectPosition.X;
result.M42 = objectPosition.Y;
result.M43 = objectPosition.Z;
result.M44 = 1.0f;
return(result);
}
/// <summary>
/// Creates the smallest <see cref="BoundingSphere"/> that can contain a specified list of points in 3D-space.
/// </summary>
/// <param name="points">List of point to create the sphere from.</param>
/// <returns>The new <see cref="BoundingSphere"/>.</returns>
public static BoundingSphere CreateFromPoints(IEnumerable <Vector3> points)
{
if (points == null)
{
throw new ArgumentNullException("points");
}
// From "Real-Time Collision Detection" (Page 89)
Vector3 minx = new Vector3(float.MaxValue, float.MaxValue, float.MaxValue);
Vector3 maxx = -minx;
Vector3 miny = minx;
Vector3 maxy = -minx;
Vector3 minz = minx;
Vector3 maxz = -minx;
// Find the most extreme points along the principle axis.
int numPoints = 0;
foreach (Vector3 pt in points)
{
numPoints += 1;
if (pt.X < minx.X)
{
minx = pt;
}
if (pt.X > maxx.X)
{
maxx = pt;
}
if (pt.Y < miny.Y)
{
miny = pt;
}
if (pt.Y > maxy.Y)
{
maxy = pt;
}
if (pt.Z < minz.Z)
{
minz = pt;
}
if (pt.Z > maxz.Z)
{
maxz = pt;
}
}
if (numPoints == 0)
{
throw new ArgumentException(
"You should have at least one point in points."
);
}
float sqDistX = Vector3.DistanceSquared(maxx, minx);
float sqDistY = Vector3.DistanceSquared(maxy, miny);
float sqDistZ = Vector3.DistanceSquared(maxz, minz);
// Pick the pair of most distant points.
Vector3 min = minx;
Vector3 max = maxx;
if (sqDistY > sqDistX && sqDistY > sqDistZ)
{
max = maxy;
min = miny;
}
if (sqDistZ > sqDistX && sqDistZ > sqDistY)
{
max = maxz;
min = minz;
}
Vector3 center = (min + max) * 0.5f;
float radius = Vector3.Distance(max, center);
// Test every point and expand the sphere.
// The current bounding sphere is just a good approximation and may not enclose all points.
// From: Mathematics for 3D Game Programming and Computer Graphics, Eric Lengyel, Third Edition.
// Page 218
float sqRadius = radius * radius;
foreach (Vector3 pt in points)
{
Vector3 diff = (pt - center);
float sqDist = diff.LengthSquared();
if (sqDist > sqRadius)
{
float distance = (float)Math.Sqrt(sqDist); // equal to diff.Length();
Vector3 direction = diff / distance;
Vector3 G = center - radius * direction;
center = (G + pt) / 2;
radius = Vector3.Distance(pt, center);
sqRadius = radius * radius;
}
}
return(new BoundingSphere(center, radius));
}
