Flexible A* Pathfinding System

1.8.1 version here!

Download

Note: The TGEA version in the download is newer than the TGE version. Most people are using TGEA now, anyways. If you want the newer version in TGE, you can port it yourself, it shouldn't be too bad. If there is some interest in it and someone does a port, just send it to me and I'll put it up here.

Installation - TGEA

Add aStar.h, aStar.cpp, aStarIO.cpp, and aStarMesh.cpp to your project (in T3D). Replace or merge aiPlayer.cpp and .h with the files in in the zip.

Add #include "T3D/aStar.h" on top of sceneState.cpp

Add the commented part in SceneState::renderCurrentImages():

PROFILE_START(RenderInstManagerRender);
   gRenderInstManager.render();
   PROFILE_END();
//aStar
#ifdef AI_RENDER
   AStar::Get()->render(this);
#endif
//aStar
   gRenderInstManager.clear();

   mInteriorList.clear();

Add this in game/tools/missionEditor/scripts/editors/creator.ed.cs line 146:

%Mission_Item[6] = "NavMesh";

Add the following function at the end of game/tools/missionEditor/gui/objectBuilderGui.ed.gui:

function ObjectBuilderGui::buildNavMesh(%this)
{
	%this.className = "NavMesh";
	%this.process();
}

In [game]/scriptsAndAssets/server/scripts/game.cs, at the end of startGame(), add

readPaths();

At the end of endGame(), add

deletePaths();

before resetMission();

For an example, add aiDemo.mis.


Installation - TGE

Add the aStar.cc and aStar.h files to your project. Replace or merge aiPlayer.cc and .h with the files in in the zip.

In sceneState.cc, after the includes, add

#include "game/aStar.h"

in renderCurrentImages(), around line 481, add the commented code

for (i = 0; i < mTranslucentEndImages.size(); i++)
      renderImage(this, mTranslucentEndImages[i]);
//aStar
#ifdef AI_RENDER
   gAStar.render(this);
#endif
//aStar
   glMatrixMode(GL_MODELVIEW);
   glPopMatrix();

Save and compile.

In creator/editor/EditorGui.cs, at line 1306, change

%Mission_Item[3] = "Trigger";
   %Mission_Item[4] = "PhysicalZone";
   %Mission_Item[5] = "Camera";

to

%Mission_Item[3] = "NavMesh";
   %Mission_Item[4] = "Trigger";
   %Mission_Item[5] = "PhysicalZone";
   %Mission_Item[6] = "Camera";

In creator/editor/objectBuilderGui.gui, at line 643, add

function ObjectBuilderGui::buildNavMesh(%this)
{
	%this.className = "NavMesh";
	%this.process();
}

In [game]/server/scripts/game.cs, at the end of startGame(), add

readPaths();

At the end of endGame(), add

deletePaths();

before resetMission();

For an example, add aiDemo.mis.

Use

To add navigation points, open the mission editor creator. NavMesh objects are under Mission Objects / Mission. The properties are:
Interval - distance between points
XSize - number of points in x direction
YSize - number of points in y direction
Height - how far up or down the object will look to place points

There are two global preferences you can change. One is $Pref::AStar::Render. It controls whether or not the navigation mesh is rendered. Turn it on when editing the mesh, turn it off otherwise. The other is $Pref::AStar::Clearence. This controls the minimum horizontal clearance between two nodes when building paths. If you change this after creating points, you need to call buildPaths for it to effect those points.

There are three functions for path caching. Do not call any of these while the mission editor is running, it may get all messed up. They are
- deletePaths Deletes all NavMesh objects and all nodes.
- writePaths Writes all nodes to a file (called [mission name].as) that is loaded automatically on mission startup. This is the only function you need to call manually; call it once you're done editing the nav mesh.
- readPaths Reads nodes from file. Returns true on success, false on faliure.

Also there is
- buildPaths Manually rebuilds navigation information, for example if an object has been moved in the way of some nodes.

There is also a compiler switch, AI_RENDER, at the top of aStar.h. Comment this out when you distribute the game to remove all the nav mesh rendering code.

There are five functions that can be called on the AIPlayer object. They will return 0 on success, -1 on failure, and 1 if the bot is already where you want it to go. They are
- findPathTo This takes either a point or an object as an argument, and simply finds a way to the point.
- findCoverFrom This also takes a point or object, and finds a place hidden from it.
- searchCover This takes no arguments, and makes the bot go to the nearest place it can't see.
- sneakUpOn This takes either a point and a vector or an object as an argument. It finds a path to the point or the object that can't be seen by it.
- wander This takes a distance as an argument and wanders around for this distance.