3D Sprites - any gotchas?
Blitz3D Forums/Blitz3D Beginners Area/3D Sprites - any gotchas?
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| Currently I'm just testing out a few bits and pieces to see if I can do what I want with the 3D sprites side of Blitz3D. To start with I used some code from the Code Archives to get it up and running. Anyway I seem to have hit a snag. I've created a square mesh which I intend to use as a background, coloured it red and placed it behind my sprite. However the sprite seems to blend with the red mesh as if alpha is set on the sprite (although it shouldn't be, and isn't as far as I can see). So it's a good bet I've done something to the original code that I shouldn't have. :) Please forgive the mess, this is just a test and an attempt to get it straight in my head as to how Blitz3D does certain things. I also apologise in advance to the guy I borrowed the code from and mangled. Global WIDTH = 600 Global HEIGHT = 600 Global halfWIDTH = WIDTH/2 Global halfHEIGHT = HEIGHT/2 ; Seed the random number generator SeedRnd(MilliSecs()) ; Program start Graphics3D WIDTH,HEIGHT,16,2 ;SetBuffer BackBuffer() ; Create and set camera camera = CreateCamera() camzoom#=1.0 ; this is default. Other values work as well. CameraZoom camera,camzoom# CameraRange camera,1,(halfWIDTH * camzoom#)+1000 ; Starfield settings Global StarsMinSpeed = 1 Global StarsMaxSpeed = 8 Global StarsTotal = 400 ; Starfield data Type StarData Field X# Field Y# Field Speed# Field Colour End Type Dim Starfield.StarData(StarsTotal) ; Load and setup our sprite sprite=LoadSprite("PS1.bmp") ; if you want the sprite to be 48*48 Pixels: ScaleSprite sprite,48/2,48/2 x# = 300 y# = 300 ; Set the sprite start angle ang#=90 ; Initialise the starfield InitStarField(StarsTotal,StarsMinSpeed,StarsMaxSpeed) ; Create test brush brush = CreateBrush() BrushColor brush,255,0,0 ; Create a blank empty mesh buffer = CreateMesh() ; Create blank surface which is attached to mesh surface = CreateSurface(buffer,brush) ; Give the mesh and surface a shape - it's just a square v0 = AddVertex(surface,-200,200,0) v1 = AddVertex(surface,200,200,0) v2 = AddVertex(surface,200,-200,0) v3 = AddVertex(surface,-200,-200,0) ; Now add triangles to make it solid and visible t0 = AddTriangle(surface,v0,v1,v2) t1 = AddTriangle(surface,v0,v2,v3) UpdateNormals buffer ; Set initial facing of player ship RotateSprite sprite,ang ;EntityOrder sprite,-1 ;EntityAlpha sprite,1 ; Main loop While KeyDown(1)=0 ; Draw our red box which will become our background PositionEntity buffer,x-halfWIDTH,halfHEIGHT-y,halfWIDTH * camzoom# + 50 ; Draw the players ship PositionEntity sprite,x-halfWIDTH,halfHEIGHT-y,halfWIDTH * camzoom# ; Turn left If KeyDown(203) ang = ang + 3 RotateSprite sprite,ang ; Turn right ElseIf KeyDown(205) ang = ang - 3 RotateSprite sprite,ang EndIf ; Roll the angle value around If ang < 0 ang = 360 + ang ElseIf ang > 359 ang = ang - 360 EndIf UpdateWorld RenderWorld ; Draw starfield ; 2D commands should be drawn after updateworld/renderworld but before flip DrawStarField(ang) Flip Wend EndGraphics End ; Initalise starfield Function InitStarField(amount,min,max) ; Set starfield to initial values For i = 0 To amount ; Initialise entry in array Starfield.StarData(i) = New StarData ; Set fields in entry Starfield(i)\X = Rand(0,GraphicsWidth()) Starfield(i)\Y = Rand(0,GraphicsHeight()) Starfield(i)\Speed = Rand(min,max) ; We want grey scale without having stars too dark to see. ; So we force the colour range into the 61 - 255 bracket. c = Rand(60,195) ; Convert from RGB into argb for writepixel etc. and store in array Starfield(i)\Colour = (c Or (c Shl 8) Or (c Shl 16) Or ($ff000000)) Next End Function ; Starfield display routine Function DrawStarField(direction#) ; We lock the screen buffer for drawing, to speed it all up LockBuffer ; Update starfield array For i = 0 To StarsTotal ; Move the star in the given direction and the given speed X# = (Starfield(i)\X) - (Starfield(i)\Speed * Cos(direction)) Y# = (Starfield(i)\Y) + (Starfield(i)\Speed * Sin(direction)) ; If star has moved off screen, relocate it If X < 0 X = GraphicsWidth() Y = Rand(0,GraphicsHeight()) ElseIf X >= GraphicsWidth() X = 0 Y = Rand(0,GraphicsHeight()) EndIf If Y < 0 Y = GraphicsHeight() X = Rand(0,GraphicsWidth()) ElseIf Y >= GraphicsHeight() Y = 0 X = Rand(0,GraphicsWidth()) EndIf ; Draw the star WritePixelFast X,Y,Starfield(i)\Colour ; Update the starfield entry Starfield(i)\X = X Starfield(i)\Y = Y Next UnlockBuffer End Function |
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| well the default sprite loading is where black is totally transparent, white is totally visible, and the alpha is adjusted for each color in between. what you can do is do LoadSprite("PS1.bmp",4) which just sets black as transparent. |
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| Ok thanks, you hit the nail on the head. That's what was going on. Now I just have to clean the image up so that having black as transparent doesn't uglify it completely. :) |
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| that or load it with flag 2 instead of flag 4 |
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