Don't draw full texture

zyclop · Post by **zyclop** » Thu Feb 07, 2008 5:04 pm

Hi,
hope you can help me ^^ I want to draw a texture at an object, but don't want to see the whole picture.

for example:

I want to see only the tree and not the black background. Is it possible to realize this? Or should I create a model with Blender or Milkshape?

--- zyclop

JP · Post by JP » Thu Feb 07, 2008 5:05 pm

you use texture->makeColorKey() with the colour you wish to be transparent i believe.

hybrid · Post by **hybrid** » Thu Feb 07, 2008 5:07 pm

Since you have a black background here you can simply use EMT_TRANSPARENT_ADD_COLOR as material type. You will have to use a billboard, though, and not draw the texture with draw2dimage or something like that. Otherwise you have to create an alpha channel (either in e.g. gimp, or by using the makeKeyColorTexture method from Irrlicht) and draw using the alpha channel.
Please check the examples provided in Irrlicht, they use these kinds of transparency quite often.

zyclop · Post by **zyclop** » Thu Feb 07, 2008 5:18 pm

ok thanx for your help ^^ I'm gonna try now.

JP · Post by JP » Fri Feb 08, 2008 9:12 am

I was going to suggest TRANSPARENCY_ADD_COLOR but that would make the tree slightly transparent too wouldn't it? As it makes the image transparent based on the colour so black is completely transparent and white is completely opaque. The fairly dark green of the tree would therefore be fairly transparent right?

hybrid · Post by **hybrid** » Fri Feb 08, 2008 10:11 am

Hmm, probably yes. There's also no threshold for that material, so except for pure white everything will be somewhat transparent. So better use the alpha channel, and be sure to change the material type to a small value (depending on how sharp you want the border of your tree).