PNG Alpha Transparency

wopag · Post by **wopag** » Tue Mar 16, 2010 3:15 pm

Im loading in a 3DS file that uses a PNG texture which has part of the texture as transparent.

Loading the 3ds file in shows the transparent sections as just white.

Do i need to load in the 3ds file then traverse the texture setting the transparency manually ?! I was expecting the transparency setting to be taken automatically from the PNG file

/Stu

wopag · Post by **wopag** » Tue Mar 16, 2010 3:33 pm

Ok so forum trawling and Ive found

setMaterialType(EMT_TRANSPARENT_ALPHA_CHANNEL_REF)

does the trick.

andres · Post by **andres** » Tue Mar 16, 2010 4:34 pm

you can also use EMT_TRANSPARENT_ALPHA_CHANNEL if u want more precision (for example semi-transparent surfaces).

hybrid · Post by **hybrid** » Tue Mar 16, 2010 8:19 pm

If you set the material properly in your 3ds file, it should be supported automatically.

Lonesome Ducky · Post by **Lonesome Ducky** » Tue Mar 16, 2010 9:25 pm

Be aware of the differences between EMT_ALPHA_CHANNEL and EMT_ALPHA_CHANNEL_REF. Alpha channel ref doesn't do any blending, so is less accurate, but it's also much faster because it doesn't matter in what order it's drawn because it doesn't blend with anything. Alpha channel on the other hand blends correctly, but is much slower.

wopag · Post by **wopag** » Wed Mar 17, 2010 2:17 pm

Im MAX you can only add alpha stuff to materials ? The transparency is stored in the PNG file, which isnt automagically being applied......

wopag · Post by **wopag** » Wed Mar 17, 2010 3:08 pm

I've just converted the model to B3D, load that into irrlicht and again the PNG transparency is ignored.

Bear_130278 · Post by **Bear_130278** » Wed Mar 17, 2010 3:25 pm

Try TGA instead

))

hybrid · Post by **hybrid** » Wed Mar 17, 2010 5:35 pm

Well, if all images are required to treat alpha channels from images for transparency, this needs to be properly exported. Both 3ds and b3d have flags for this purpose, which would need to be set in this case. Otherwise you are required to set these flags manually after loading, e.g. by checking the texture names and enabling the transparency material.