Hey guys!!
I took this HTML5 example and adapted it to B4A.
I hope the code is self-explanatory, if not, I'll be here to help.
Once again I'm using panels, but you can use whatever objects you want to represent the stars. I recommend, as always, LibGDX.
I took this HTML5 example and adapted it to B4A.
I hope the code is self-explanatory, if not, I'll be here to help.
Once again I'm using panels, but you can use whatever objects you want to represent the stars. I recommend, as always, LibGDX.
B4X:
#Region Project Attributes
#ApplicationLabel: 3D Starfield Example
#VersionCode: 1
#VersionName:
'SupportedOrientations possible values: unspecified, landscape or portrait.
#SupportedOrientations: Landscape
#CanInstallToExternalStorage: False
#End Region
#Region Activity Attributes
#FullScreen: True
#IncludeTitle: False
#End Region
Sub Process_Globals
Dim Main_Engine As Timer
End Sub
Sub Globals
'Starfield
Dim number_of_stars = 64 As Float
Dim star_speed = 0.4 As Float
Dim max_depth = 32 As Float
Dim star_x(number_of_stars) As Float
Dim star_y(number_of_stars) As Float
Dim star_z(number_of_stars) As Float
Dim smin = -25 As Int
Dim smax = 26 As Int
Dim star(number_of_stars) As Panel
Dim centerX = 50%x As Float
Dim centerY = 50%y As Float
Private TouchScreen As Panel
End Sub
Sub Activity_Create(FirstTime As Boolean)
Activity.LoadLayout("Test")
For i = 0 To (number_of_stars - 1)
'Initialize 3D Coordinates
star_x(i) = Rnd(smin, smax)
star_y(i) = Rnd(smin, smax)
star_z(i) = Rnd(1, max_depth)
'Initialize Panels
star(i).Initialize("Star")
Activity.AddView(star(i), 0, 0, 0, 0)
Next
Main_Engine.Initialize("Main_Engine", 16)
Main_Engine.Enabled = True
TouchScreen.Left = 0%x
TouchScreen.Top = 0%x
TouchScreen.Width = 100%x
TouchScreen.Height = 100%y
TouchScreen.BringToFront
End Sub
Sub Activity_Resume
Main_Engine.Enabled = True
End Sub
Sub Activity_Pause (UserClosed As Boolean)
Main_Engine.Enabled = False
End Sub
Sub Main_Engine_Tick
Starfield(10, centerX, centerY, star_speed)
End Sub
Sub Starfield(star_size As Float, x_center As Float, y_center As Float, speed As Float)
For i = 0 To (number_of_stars - 1)
'Moves the star in the z-axis
star_z(i)= star_z(i) - speed
'Resets the star position once it's offscreen
If star_z(i) <= 0 Then
star_x(i) = Rnd(smin, smax)
star_y(i) = Rnd(smin, smax)
star_z(i) = max_depth
End If
'Black magic happens here, can't explain this part (3D to 2D conversion), I only know it works
Dim k = 128 / star_z(i) As Float
Dim px = star_x(i) * k + x_center As Float
Dim py = star_y(i) * k + y_center As Float
'Display the star as long as its 2D position is on screen
If px >= 0%x AND px <= 100%x AND py >= 0%x AND py <= 100%y Then
Dim size = (1 - (star_z(i) / 32.0)) * star_size As Float
Dim shade = (1 - (star_z(i) / 32.0)) * 255 As Float
'Displaying a single star:
'The Aplha level is given by how distant in the z-axis the star is
star(i).Color = Colors.ARGB(shade, 0, Rnd(128,192), Rnd(192,255))
'Set the star size according to the z-axis distance
star(i).Width = size
star(i).Height = size
'Makes px and py the center of the star
star(i).Left = px - (star(i).Width / 2)
star(i).Top = py - (star(i).Height / 2)
'=====================================================================================================
'LibGDX "Sub LG_Render" code example:
' Batch.DrawRegion2(star(i), px - Half_of_the_star_size, py - Half_of_the_star_size, size, size)
'=====================================================================================================
End If
Next
End Sub
Sub TouchScreen_Touch (Action As Int, X As Float, Y As Float)
Select Action
Case Activity.ACTION_DOWN
centerX = X
centerY = Y
star_speed = star_speed * 2
Case Activity.ACTION_MOVE
centerX = X
centerY = Y
Case Activity.ACTION_UP
star_speed = star_speed / 2
End Select
End SubAttachments
Last edited:
