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View Full Version : basic: texture layers (overlaying)



pfash
11-10-2003, 08:56 PM
I know this is sooo basic but I need a hint:
I want to put one image on top of another (layering 2 textures on the same surface) ...

so that the one on top (let's say it is a few lines of graphitti) appear on the lower image (let's say an image of a brick wall) without the areas in between the graphitti lines blocking out any of the bricks below.

Does this require an alpha mask? Or can I just have two textures on the same surface and set them so that the white areas (or black areas if they need to be that color) become transparent making the graphitti appear painted on the brick wall.

I am floundering. Any help is greatly appreciated.
Paul

murdoch
11-11-2003, 03:05 AM
yep, you'll need a mask. one surface - 3 layers - 1) brick wall. 2) graffiti. 3) mask - set the blending mode to alpha, white areas are 'holes' - this affects only the layer directly below.

you may be able to add an alpha channel to the graffiti file and it may automatically mask - not sure about this though.

FenrirWolf
11-11-2003, 11:43 AM
Yeah, if you use some file format that supports alpha channels (.psd, .tga, .png) and one is actually present in the file, it works the same as if using an alpha mask layer. It just messes up the OpenGL preview. :)

pfash
11-12-2003, 01:11 PM
Thanks Murdoch and FenrirWolf