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);
}
