Have A* Path. How do I Properly Follow it?

Jacob Roman · 2012-01-05T00:28:39

I feel that my method of following the A* path is totally wrong. I basically been checking the angle of the next tile for the monster to follow which seems to work, but I run into situations where if the next tile it must approach is at an angle and theres a wall there, the monster will drag along the wall till it reaches it. The A* Path I have literally starts at the Monsters Tile coordinate and goes all the way to the Players Tile coordinate, which is why I must check the next tile the monster must go in the array. But somethings iffy. What is the proper way for a sprite to go from one tile to another to follow the A* Star path you have? Here's what I currently have. If anyone has any ideas let me know. I can convert C++ and C# code to VB since I know everyone on this site mainly uses that. Public Sub Follow_AStar_Path(Map As Map_Type, Predator As Sprite_Type, Prey As Sprite_Type, ByVal Speed As Single) Dim AStar_Position As Vector Dim Distance As Single Dim Angle As Single Dim Velocity As Vector Dim Vec As Vector If Predator.Path_Found = True And Predator.Path_Hunt = False Then If IsArrayInitialized(VarPtrArray(Predator.AStar_Path)) = True Then If Predator.Current_Path > 0 Then AStar_Position.X = (Predator.AStar_Path(Predator.Current_Path - 1).X * TILE_SIZE) + (TILE_SIZE / 2) AStar_Position.Y = (Predator.AStar_Path(Predator.Current_Path - 1).Y * TILE_SIZE) + (TILE_SIZE / 2) Angle = Radian_To_Degree(Get_Radian(Predator.Center_of_Sprite_Position.X, Predator.Center_of_Sprite_Position.Y, AStar_Position.X, AStar_Position.Y)) Vec.X = AStar_Position.X - Predator.Center_of_Sprite_Position.X Vec.Y = AStar_Position.Y - Predator.Center_of_Sprite_Position.Y Velocity.X = Cos(Angle * PI / 180) * Speed Velocity.Y = Sin(Angle * PI / 180) * Speed Predator.Position.X = Predator.Position.X + Velocity.X Predator.Position.Y = Predator.Position.Y + Velocity.Y End If If (Predator.Center_of_Tile_Coordinates.X = Prey.Center_of_Tile_Coordinates.X And Predator.Center_of_Tile_Coordinates.Y = Prey.Center_of_Tile_Coordinates.Y) Then Exit Sub End If Distance = Sqr(Vec.X * Vec.X + Vec.Y * Vec.Y) If Int(Distance) <= 0 Then Predator.Current_Path = Predator.Current_Path - 1 If Predator.Current_Path <= 0 Then Predator.Current_Path = 0 End If End If Else Clear_AStar Map End If End Sub

Artificial Intelligence Programming

Started by Psychopathetica December 24, 2011 05:32 PM

9 comments, last by wodinoneeye 12 years, 10 months ago

wodinoneeye

1,691

January 05, 2012 12:28 AM

You could NOT recalculate the A* until your sprite reaches the next tile it was headed for.
Let it reach that understood OK position and then you can recalculate.

The original grid of nodes would be used as a approximation of movement (If your terrain is more complex
your navigation network will have to reflect that if its causing issues) If the grid is too crude then it still can be used as a coarse mechanism but then you would have to have a 'fine' navigation for the point to point movement to make it aesthetic enough (to have a bounding box of the object not collide with corners, turning radius limitations, etc).

At a certain point it may be better to have a better (non-grid) node/edge network based on portals and centers of 'rooms' etc.. that will go further to eliminate the 45 degree crudities of the simple 2D regular grid..

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Have A* Path. How do I Properly Follow it?

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Have A* Path. How do I Properly Follow it?

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