RE: 3D Arrows

• To: mathgroup at smc.vnet.net
• Subject: [mg88132] RE: [mg88114] 3D Arrows
• From: "Jose Luis Gomez" <jose.luis.gomez at itesm.mx>
• Date: Sat, 26 Apr 2008 03:41:40 -0400 (EDT)
• References: <200804250928.FAA08122@smc.vnet.net>

```(* The following code defines a very simple command for 3d arrows, *)
(* copy-paste to Mathematica and press Shift-Enter, *)
(* no-output will be generated, but the new arrow3d command *)
(* will be ready to be used, see example below *)

arrow3d[{x1_, y1_, z1_}, {dx_, dy_, dz_}] :=
arrow3d[{{x1, y1, z1}, {x1 + dx, y1 + dy, z1 + dz}}];
arrow3d[{x1_, y1_, z1_}, d_] :=
arrow3d[{{x1, y1, z1}, {x1 + d, y1 + d, z1 + d}}];
arrow3d[{{x1_, y1_, z1_}, {x2_, y2_, z2_}}] :=
Module[{vector, magnitud, normal, vectornormal, cruz,
vectorbinormal},
vector = {x2 - x1, y2 - y1, z2 - z1};
magnitud = Norm[vector];
normal = {0, z1 - z2, y2 - y1};
vectornormal = magnitud*normal/Norm[normal];
cruz = Cross[vector, vectornormal];
vectorbinormal = magnitud*cruz/Norm[cruz];
{Cylinder[{{x1, y1, z1}, {x1, y1, z1} + 0.8 vector},
0.01 magnitud],
Polygon[{{x1, y1, z1} + 0.8 vector +
0.1 vectornormal, {x1, y1, z1} + 0.8 vector -
0.1 vectornormal, {x2, y2, z2}}],
Polygon[{{x1, y1, z1} + 0.8 vector +
0.1 vectorbinormal, {x1, y1, z1} + 0.8 vector -
0.1 vectorbinormal, {x2, y2, z2}}]}
];

(* EXAMPLE: After evaluating (Shift-Enter) the code above, evaluate *)
(* the example below *)

Graphics3D[{Sphere[{1, 1, 1}, 0.2],
arrow3d[{{1.5, 1, 1}, {2, 2, 2}}],
arrow3d[{{1.5, 0, 1}, {-2, -2, 2}}]}, PlotRange -> All]

(* hope that helps *)
(* Jose *)
(* Mexico *)

-----Mensaje original-----
De: Robert M. Lurie [mailto:RMLURIE at ALUM.MIT.EDU]
Enviado el: Viernes, 25 de Abril de 2008 04:28 a.m.
Para: mathgroup at smc.vnet.net
Asunto: [mg88114] 3D Arrows

Apparently Arrows is only a 2D graphic. Is there a way to make an arrow
in 3D?
Robert M Lurie

```

• References:
• 3D Arrows
• From: "Robert M. Lurie" <RMLURIE@ALUM.MIT.EDU>
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