Updating indexing in ArticulationBody APIs for all joints (#22)

* Adding variable names for indexes used in ArticulationnBody APIs

* Setting index value for xAxis

Author: vidurvij-Unity

Runtime/UrdfComponents/UrdfJoints/UrdfJoint.cs

@@ -34,6 +34,8 @@ public enum JointTypes
             Planar
         }
 
+    public int xAxis = 0;
+    
 #if UNITY_2020_1_OR_NEWER
         protected UnityEngine.ArticulationBody unityJoint;
         protected Vector3 axisofMotion;

Runtime/UrdfComponents/UrdfJoints/UrdfJointContinuous.cs

@@ -42,7 +42,7 @@ public override float GetPosition() // Check Units
         {
 
 #if UNITY_2020_1_OR_NEWER
-            return unityJoint.jointPosition[0];
+            return unityJoint.jointPosition[xAxis];
 #else
                 return -((HingeJoint)unityJoint).angle * Mathf.Deg2Rad;
 #endif
@@ -55,7 +55,7 @@ public override float GetPosition() // Check Units
         public override float GetVelocity()
         {
             #if UNITY_2020_1_OR_NEWER
-                return unityJoint.velocity[0];
+                return unityJoint.velocity[xAxis];
             #else
             return -((HingeJoint)unityJoint).velocity * Mathf.Deg2Rad;
             #endif
@@ -68,7 +68,7 @@ public override float GetVelocity()
         public override float GetEffort()
         {
             #if UNITY_2020_1_OR_NEWER
-                return unityJoint.jointForce[0];
+                return unityJoint.jointForce[xAxis];
             #else
                 return -((HingeJoint)unityJoint).motor.force;
             #endif

Runtime/UrdfComponents/UrdfJoints/UrdfJointPrismatic.cs

@@ -60,7 +60,7 @@ public static UrdfJoint Create(GameObject linkObject)
         public override float GetPosition()
         {
             #if UNITY_2020_1_OR_NEWER
-                return unityJoint.jointPosition[3];
+                return unityJoint.jointPosition[xAxis];
             #else
             return Vector3.Dot(unityJoint.transform.localPosition - unityJoint.connectedAnchor, unityJoint.axis);
             #endif
@@ -73,7 +73,7 @@ public override float GetPosition()
         public override float GetVelocity()
         {
 #if UNITY_2020_1_OR_NEWER
-            return unityJoint.velocity[3];
+            return unityJoint.velocity[xAxis];
 #else
             return float.NaN;
 #endif
@@ -86,7 +86,7 @@ public override float GetVelocity()
         public override float GetEffort()
         {
 #if UNITY_2020_1_OR_NEWER
-            return unityJoint.jointForce[3];
+            return unityJoint.jointForce[xAxis];
 #else
                 return float.NaN;
 #endif

Runtime/UrdfComponents/UrdfJoints/UrdfJointRevolute.cs

@@ -47,7 +47,7 @@ public static UrdfJoint Create(GameObject linkObject)
         public override float GetPosition()
         {
             #if UNITY_2020_1_OR_NEWER
-            return ((ArticulationBody)unityJoint).jointPosition[0] * Mathf.Deg2Rad;
+            return ((ArticulationBody)unityJoint).jointPosition[xAxis] * Mathf.Deg2Rad;
 #else
                         return -((HingeJoint)unityJoint).angle * Mathf.Deg2Rad;
 #endif
@@ -60,7 +60,7 @@ public override float GetPosition()
         public override float GetVelocity()
         {
             #if UNITY_2020_1_OR_NEWER
-                return ((ArticulationBody)unityJoint).jointVelocity[0] * Mathf.Deg2Rad;
+                return ((ArticulationBody)unityJoint).jointVelocity[xAxis] * Mathf.Deg2Rad;
             #else
                         return -((HingeJoint)unityJoint).velocity * Mathf.Deg2Rad;
             #endif
@@ -73,7 +73,7 @@ public override float GetVelocity()
         public override float GetEffort()
         {
             #if UNITY_2020_1_OR_NEWER
-                return unityJoint.jointForce[0];
+                return unityJoint.jointForce[xAxis];
             #else
                         return -((HingeJoint)unityJoint).motor.force;
             #endif