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Author Topic: [bb] Automatic Starfield generator by _33 [ 1+ years ago ]  (Read 665 times)

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[bb] Automatic Starfield generator by _33 [ 1+ years ago ]
« on: June 29, 2017, 12:28:40 AM »
Title : Automatic Starfield generator
Author : _33
Posted : 1+ years ago

Description : It's a simple function set that I made a while back to help me get an easy to maintain starfield.  Every frame, you call AnimateStarfield().  You can put some parms to adjust exactly where you want it to be.  Usually your x and z are the same as where your view is.  The starfield always go in the same direction.  I didn't make it too advanced.  And there's a function to delete the starfield, of course.

Code :
Code: BlitzBasic
  1. ; FILENAME: func_stars.bb
  2. ;----------------------------------------------------------------------------------------
  3. ; starfield management
  4. ;----------------------------------------------------------------------------------------
  5. ; Define the type for each stars in a starfield
  6. Type star_info
  7.    Field ptr
  8.    Field xpos#
  9.    Field ypos#
  10.    Field zpos#
  11.    Field velocity#
  12. End Type
  13.  
  14. Global star_count% = 0
  15.  
  16. Function AnimateStarfield(x#=0,y#=0,z#=0,occ%=6)
  17.    Local overlap_x# = Rnd(0, 2500.0)
  18.    Local overlap_z# = Rnd(0, 5000.0)
  19.  
  20.    If Rand(1,occ%) = occ% Then AddStar(x#, y#, z#, overlap_x#, overlap_z#)
  21.  
  22.    For star.star_info = Each star_info
  23.        starxpos# = starxpos# + starvelocity#
  24.  
  25.        If (starxpos#) > (x# + overlap_x# + 2500.0) Then
  26.           FreeEntity starptr
  27.           Delete star.star_info
  28.           star_count% = star_count% - 1
  29.        Else
  30.           ;PositionMesh starptr, starvelocity#, 0, 0
  31.           PositionEntity starptr, starxpos#, starypos#, starzpos#
  32.        EndIf
  33.    Next
  34. End Function
  35.  
  36.  
  37. Function DeleteAllStars()
  38.    For star.star_info = Each star_info
  39.       FreeEntity starptr
  40.       Delete star.star_info
  41.    Next
  42.    star_count% = 0
  43. End Function
  44.  
  45.  
  46. Function AddStar(xref#, yref#, zref#, overlap_x#, overlap_z#)
  47.    Local starsize# = Rnd(0.5,2.01)
  48.    Local speed# = Rnd(2.0,8.0)
  49.  
  50.    If starsize# > 2 Then
  51.       starsize# = 18.0 - speed#
  52.    EndIf
  53.  
  54.    star.star_info = New star_info
  55.  
  56. ;   starptr      = make_star (2 + Int starsize#)
  57.    starptr       = CreateSphere(2 + Int starsize#)
  58.    starxpos#     = xref# - overlap_x# - 2500.0
  59.    starzpos#     = zref# - overlap_z# + 2500.0
  60.    starypos#     = 650.0 + Rnd(0, 350.0)
  61.    starvelocity# = speed#
  62.  
  63.   ; EntityTexture starptr, ptr_texture(127),0,1
  64.    EntityBlend starptr, 3
  65.    EntityFX starptr, 1
  66.    ScaleEntity starptr, starsize#, starsize#, starsize#
  67.    EntityColor starptr, 255, 255, 255
  68.    star_count% = star_count% + 1
  69. ;   PositionEntity starptr, starxpos#, starypos#, starzpos#
  70.  
  71. End Function


Comments :


Boiled Sweets(Posted 1+ years ago)

 And an example of how to use the functions please?


_33(Posted 1+ years ago)

 <div class="quote"> Every frame, you call AnimateStarfield(). You can put some parms to adjust exactly where you want it to be. </div>Then call DeleteAllStars() to delete the starfield (useful when you leave the "in game" scene).CODE EXAMPLE:
Code: [Select]
Include "func_stars.bb"
Graphics3D 1024,768,32,1
Light=CreateLight()
cam=CreateCamera()
CameraRange cam, .01, 10000
land = CreatePlane()
tex = create_checker_tex(64,96,64,128,192,128,1,1)
EntityTexture land, tex
EntityAlpha land, 0.5
mirror=CreateMirror()
sens# = 0.25
centerofworld = CreatePivot () : PositionEntity centerofworld, 0,1,0
PositionEntity cam,0,1,0
For i = 1 To 1000 : AnimateStarfield() : Next ; let it create and move stars for 1000 cycles
While Not KeyDown(1)
   x# = x + sens : z# = z + sens
   PositionEntity centerofworld,Sin(x),1,Cos(z)
   PointEntity cam, centerofworld
   AnimateStarfield() ; cycling through the starfield algorythm
   RenderWorld ()
   Color 0,255,0
   Text 0,0, "PRESS [ESC] TO EXIT"
   Flip
Wend
DeleteAllStars() ; deletes all star entities
End

Function create_checker_tex(red1,green1,blue1,red2,green2,blue2,scale_u#,scale_v#)
   texture_handle = CreateTexture(32,32,256)
   SetBuffer TextureBuffer(texture_handle)
   Color red1,green1,blue1 : Rect 0,0,32,32 : Color red2,green2,blue2 : Rect 0,0,16,16,1 : Rect 16,16,16,16,1
   ScaleTexture texture_handle,scale_u#,scale_v#
   SetBuffer BackBuffer()
   Return texture_handle
End Function
Do not forget to have the include file in the same directory as this test. [/i]

 

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