Transparant textures? (png)
Blitz3D Forums/Blitz3D Programming/Transparant textures? (png)
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| Hi, I have a png which I made in photoshop, it has transparant parts. In milkshape I created a square (plane), and it shows it right (transparant). But in blitz (b3d file for the model), I see the transparant parts in white. I tried using entityalpha (0, 0.5 and 1) but it doesn't work. Any advice? Thanks. |
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| Try using flag 2 on the LoadTexture() command for the PNG. |
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| if it's a 24 Bit PNG, the transparent color needs to be black when loaded with Flag 4 (masked) or as Genexi said, 2 for alpha transparency. With alpha-transparency it works this way: the darker the pixels of the texture, the more transparent they are. (Note: unlike with Mode Flag 4, using Mode 2 can cause Z-Order problems when you have mutliple alpha-transparent objects in a scene) From what you said you rather want to use a mask, so use something like tex=loadtexture("x.png",4) While PNG and GIF do know some kind of "transparent" color, Blitz expects those parts to be black (0,0,0). If you are using 32 Bit PNG, the highest 8 Bits, aka channel 4, are used as alpha channel. This way you can set the transparency of each pixel independently from its brightness. If you use Flag 4 here, the alpha-channel pixel must be Zero to be transparent. So basicly its: with 24 Bits you have Red-Green-Blue channels, and black is transparent (in Mode 4) with 32 Bits you have Alpha-Red-Green-Blue channels, and the transparency is defined in the alpha channel, in Mode 4 pixels need to be Zero for transparency, in Mode 2 it may be any value from 0 to 255 for a more or less transparent pixel. Please note: due to mipmapping and filtering processes, the contours of a masked texture may look darkish, fading to black, especially when watched from the distance. You surely want to prevent this ugly behaviour, there are two ways: -use an Alpha channel that defines the masked parts and on the RGB channels use a background color that fits with the main colors of the object, example: when its some leaf, use a green background. -method 2: load the texture and replace each texel that is black with a texel that has a better color for the background (as described) and simply set the alpha channel of those texels in the texturebuffer to zero. Example:
; (assuming the masked parts are black, 24 Bit PNG and it's some green stuff on the texture, eg. leaf etc.)
tex=loadtexture("tex.png")
setbuffer texturebuffer(tex)
lockbuffer()
for j=0 to textureheight(tex)-1
for i=0 to texturewidth(tex)-1
rgb=readpixelfast(i,j) and $FFFFFF
if rgb=0 ; if it's black
writepixelfast i,j,$0000AA00 ; write a greenish pixel, alphabyte=0
endif
next
next
unlockbuffer()
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| ok, thanks, I got it working. too bad I have to load the texture seperately and not just use my textured milkshape model (in milkshape it shows the png transparancy like it should). |
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| You don't have to load the texture separately, you can use the command texturefilter, read this http://www.blitzbasic.com/b3ddocs/command.php?name=TextureFilter&ref=3d_cat Basically give your transparent texture a name or flag in its filename and then perform the texturefilter command after graphics3d. |
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