Temporarily provide colliding projectile

The collision configuration functions lacked access to the current
projectile and the position of collision. Both can now be accessed via
the pointer of the colliding projectile which is temporarily provided
with the global variable GFA_ProjectilePtr. It can be accessed with

    var oCItem proj; proj = _^(GFA_ProjectilePtr);
    Print(proj.name);

This unconventional method of providing information to the config
functions preserves the function signatures and thus prevents issues in
backward compatibility.

_work/data/Scripts/Content/GFA/_intern/collision.d

@@ -216,7 +216,9 @@ func void GFA_CC_ProjectileCollisionWithNpc() {
     } else {
         // Retrieve the collision behavior based on the shooter, target and the material type of their armor
         var C_Npc target; target = _^(MEMINT_SwitchG1G2(EBX, MEM_ReadInt(/*esp+1ACh-190h*/ ESP+28)));
+        GFA_ProjectilePtr = MEM_ReadInt(arrowAI+oCAIArrowBase_hostVob_offset); // Temporarily provide projectile
         collision = GFA_CC_GetCollisionWithNpc_(shooter, target);
+        GFA_ProjectilePtr = 0;
     };
 
     // Apply collision behavior
@@ -359,7 +361,9 @@ func void GFA_CC_ProjectileCollisionWithWorld() {
     var int speed; speed = sqrtf(addf(addf(sqrf(vel[0]), sqrf(vel[1])), sqrf(vel[2]))); // Norm of vel
 
     // Retrieve the collision behavior based on the shooter, the material types and the textures of the collision object
+    GFA_ProjectilePtr = projectilePtr; // Temporarily provide projectile
     var int collision; collision = GFA_CC_GetCollisionWithWorld_(shooter, materials, textures);
+    GFA_ProjectilePtr = 0;
     const int DESTROY = 0; // Projectile breaks and vanishes
     const int STUCK   = 1; // Projectile stays and is stuck in the surface of the collision object
     const int DEFLECT = 2; // Projectile deflects off of the surfaces and bounces off

_work/data/Scripts/Content/GFA/_intern/const.d

@@ -131,6 +131,8 @@ const float  GFA_SCATTER_MAX        = 6.0;                  // (Visual angle)/2
 var   int    GFA_CollTrj[6];                                // Projectile trajectory of last collision candidate
 var   string GFA_HitModelNode;                              // Name of model node that was hit
 
+var   int    GFA_ProjectilePtr;                             // Pointer of currently colliding projectile (temporary)
+
 const int    DMG_NO_CHANGE          = 0;                    // Do not adjust the damage
 const int    DMG_DO_NOT_KNOCKOUT    = 1;                    // Normal damage, shot may kill but never knockout (HP != 1)
 const int    DMG_DO_NOT_KILL        = 2;                    // Normal damage, shot may knockout but never kill (HP > 0)