From 4e0bb49394d303c7c7707f85b02e47b7c2053201 Mon Sep 17 00:00:00 2001
From: Melanie
Date: Mon, 23 Jan 2012 13:48:16 +0100
Subject: Fix llLookAt the right way

---
 .../Shared/Api/Implementation/LSL_Api.cs           | 43 ++++++++++++----------
 1 file changed, 24 insertions(+), 19 deletions(-)

(limited to 'OpenSim/Region/ScriptEngine')

diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
index ac22638..7af5d2d 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
@@ -3040,34 +3040,39 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
         public void llLookAt(LSL_Vector target, double strength, double damping)
         {
             m_host.AddScriptLPS(1);
-            // Determine where we are looking from
-            LSL_Vector from = llGetPos();
 
-            // Work out the normalised vector from the source to the target
-            LSL_Vector delta = llVecNorm(target - from);
-            LSL_Vector angle = new LSL_Vector(0,0,0);
+            // Get the normalized vector to the target
+            LSL_Vector d1 = llVecNorm(target - llGetPos());
 
-            // Calculate the yaw
-            // subtracting PI_BY_TWO is required to compensate for the odd SL co-ordinate system
-            angle.x = llAtan2(delta.z, delta.y) - ScriptBaseClass.PI_BY_TWO;
+            // Get the bearing (yaw)
+            LSL_Vector a1 = new LSL_Vector(0,0,0);
+            a1.z = llAtan2(d1.y, d1.x);
 
-            // Calculate pitch
-            angle.y = llAtan2(delta.x, llSqrt((delta.y * delta.y) + (delta.z * delta.z)));
+            // Get the elevation (pitch)
+            LSL_Vector a2 = new LSL_Vector(0,0,0);
+            a2.y= -llAtan2(d1.z, llSqrt((d1.x * d1.x) + (d1.y * d1.y)));
 
-            // we need to convert from a vector describing
-            // the angles of rotation in radians into rotation value
+            LSL_Rotation r1 = llEuler2Rot(a1);
+            LSL_Rotation r2 = llEuler2Rot(a2);
+            LSL_Rotation r3 = new LSL_Rotation(0.000000, 0.707107, 0.000000, 0.707107);
 
-            LSL_Rotation rot = llEuler2Rot(angle);
-
-            // Per discussion with Melanie, for non-physical objects llLookAt appears to simply
-            // set the rotation of the object, copy that behavior
-            if (strength == 0 || m_host.PhysActor == null || !m_host.PhysActor.IsPhysical)
+            if (m_host.PhysActor == null || !m_host.PhysActor.IsPhysical)
             {
-                llSetRot(rot);
+                // Do nothing if either value is 0 (this has been checked in SL)
+                if (strength <= 0.0 || damping <= 0.0)
+                    return;
+
+                llSetRot(r3 * r2 * r1);
             }
             else
             {
-                m_host.StartLookAt(Rot2Quaternion(rot), (float)strength, (float)damping);
+                if (strength == 0)
+                {
+                    llSetRot(r3 * r2 * r1);
+                    return;
+                }
+
+                m_host.StartLookAt(Rot2Quaternion(r3 * r2 * r1), (float)strength, (float)damping);
             }
         }
 
-- 
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