Creating 2D paths

BlitzMax Forums/BlitzMax Programming/Creating 2D paths

Takis76 (Posted 2015) [#1]

Hello again, I would like to ask how it is possible to create a 2D path and on this path will move 2D sprites. I thought if I was paint one with lines but it will appear on the screen and how some image or sprite will follow this path. (To do some special effects).

Ifq200 (Posted 2015) [#2]

Use an array with X and y Local path:int[,] path = new int[amount, 2]

Takis76 (Posted 2015) [#3]

What is the amount? and 2? :)

H&K (Posted 2015) [#4]

Amount is either the amount of steps OR the amount of turns depending on how YOU do it. "2" is x an y

Ifq200 (Posted 2015) [#5]

SuperStrict Graphics 800,600 Local path:Int[,] 'pathway Local angle:Float Local spd:Int = 1 Local index:Int = 0 'current path Local x:Float, y:Float 'rect position path = New Int[10,2] 'path SeedRnd MilliSecs() For Local i:Int = 0 To 9 path[i,0] = Rnd(10, 780); path[i,1] = Rnd(10,580) 'generate random path Next x = path[0,0]; y = path[0,1] 'set rect position at first path While Not KeyHit(KEY_ESCAPE) Cls SetColor 255,255,255 For Local i:Int = 0 To 8 DrawLine( path[i,0], path[i,1], path[i+1,0], path[i+1,1] ) 'draw path Next angle = ATan2( path[index+1,1] - path[index,1], path[index+1,0] - path[index,0] ) 'calculcate angle to next waypoint x = x + Cos(angle) * spd; y = y + Sin(angle) * spd 'update position If Distance(x, y, path[index+1,0], path[index+1,1]) =< 2 Then 'if waypoint next index:+ 1 If index = 9 Then 'last waypoint index = 0; x = path[0,0]; y = path[0,1] 'reset End If End If SetColor 0,255,0 DrawRect( x-5, y-5, 10, 10) Flip Wend End Function Distance:Int(x1:Int, y1:Int, x2:Int, y2:Int) Local s1:Int = x1 - x2 Local s2:Int = y1 - y2 If s1 < 0 Then s1 = -s1 If s2 < 0 Then s2 = -s2 s1 = s1 * s1 s2 = s2 * s2 Return Sqr(s1+s2) End Function

TomToad (Posted 2015) [#6]

Here's how I would do it, using Linked List and TLink. A little more complicated, but a lot more flexible than arrays. SuperStrict SeedRnd(MilliSecs()) 'randomize the randomizer Type TPoint ' defines a point on the screen Field x:Float, y:Float End Type Local List:TList = CreateList() 'List of points Type TSprite Field SourcePoint:TLink = Null, DestPoint:TLink = Null 'moving sprite from SourcePoint to DestPoint Field Time:Int 'the time it will take to move from SourcePoint to DestPoint Field StartTime:Int 'the time the sprite started moving along this path Field x:Float, y:Float End Type Local Sprite:TSprite = New TSprite 'create the sprite Local Speed:Float = 100.0 'Speed in pixels/sec For Local i:Int = 1 To 10 'populate the list with random points Local Point:TPoint = New TPoint Point.x = Rnd(0,800) Point.y = Rnd(0,600) List.AddLast(Point) Next Graphics 800,600 Local Time:Int Local SourcePoint:TPoint, DestPoint:TPoint While Not KeyHit(KEY_ESCAPE) And Not AppTerminate() Time = MilliSecs() 'figure out where the sprite is suppose to be If Sprite.SourcePoint 'If movement has already started While Sprite.StartTime+Sprite.Time < Time 'Sprite has finished the line Local OverTime:Int = Time - (Sprite.Starttime+Sprite.Time) 'How much time has the Sprite spent on the next line Sprite.SourcePoint = Sprite.DestPoint Sprite.DestPoint = Sprite.DestPoint.NextLink() 'get the next point in the list If Not Sprite.DestPoint 'No more points. Move sprite back to the beginning Sprite.SourcePoint = List.FirstLink() Sprite.DestPoint = Sprite.SourcePoint.NextLink() End If SourcePoint = TPoint(Sprite.SourcePoint.Value()) 'get the TPoint from the link DestPoint = TPoint(Sprite.DestPoint.Value()) Local Distance:Float = Sqr((DestPoint.x-SourcePoint.x)^2+(DestPoint.y-SourcePoint.y)^2) 'distance of line Sprite.Time = (Distance/Speed) * 1000 'Number of milliseconds Sprite.StartTime = Time - OverTime 'Set the StartTime to the current time - the overtime Wend 'Get the TPoints from the TLinks SourcePoint = TPoint(Sprite.SourcePoint.Value()) DestPoint = TPoint(Sprite.DestPoint.Value()) 'calculate percentage on this line Local TimeSpent:Int = Time - Sprite.StartTime Local Percent:Float = Float(TimeSpent)/Float(Sprite.Time) 'calculate the distance traveled in x and y direction Local dx:Float = Float(DestPoint.x-SourcePoint.x)*Percent Local dy:Float = Float(DestPoint.y-SourcePoint.y)*Percent 'put the sprite where we need it Sprite.x = SourcePoint.x + dx Sprite.y = SourcePoint.y + dy Else 'First run, initialize the sprite Sprite.SourcePoint = List.FirstLink() Sprite.DestPoint = Sprite.SourcePoint.NextLink() 'Get the TPoint from the TLink SourcePoint = TPoint(Sprite.SourcePoint.Value()) DestPoint = TPoint(Sprite.DestPoint.Value()) 'Calculate distance Local Distance:Float = Sqr((DestPoint.x - SourcePoint.x)^2+(DestPoint.y - SourcePoint.y)^2) Sprite.Time = (Distance/Speed) * 1000 'calculate the time to traverse this line Sprite.StartTime = Time Sprite.X = SourcePoint.x Sprite.y = SourcePoint.y End If Cls Local OldPoint:TPoint = Null 'no lines have been drawn yet SetColor 0,0,255 For Local Point:TPoint = EachIn List If OldPoint 'if we are on the second point or greater, then draw a line DrawLine OldPoint.x,OldPoint.y,Point.x,Point.y End If OldPoint = Point 'Set OldPoint to point to the current point Next SetColor 255,0,0 DrawOval Sprite.x - 10, Sprite.y - 10,20,20 SetColor 0,255,0 DrawOval Sprite.x - 8, Sprite.y - 8,16,16 Flip Wend

Takis76 (Posted 2015) [#7]

I run the code and is what I am looking exactly , but I haven't understand how to create your path. The path variable is a 2D array. The first index of the array is the path serial number (Incremental number] What you put in the second array index? It should be 3D array if the first is the number of the path point and the second and third should be the x,y positions of this point. I try to understand why u use 2D array instead of 3D array. According how to understand it and how is could be implemented. [0001,50,23] [0002,50,27] [0003,52,25] Or as I understood after , you store in the first index the number of the path point and in the second index which is from 0 to 1 the x,y coordinates. Something like this one: path[0,0] = 5 path[0,1] = 5 path[1,0] = 7 path[1,1] = 8 path[2,0] = 12 path[2,1] = 9 This means the number 0 of the first index is the incremental number and the second index is from 0 - 1

Takis76 (Posted 2015) [#8]

I did something but it needs a lots of adjustments to put the path points correctly until create a nice path not random. I created a small program which I draw the dots of the path and generates the positions x,y with mouse for each point of the path and save them in text file. Then I add the points manually :) thank you this does the effect.