Blend experiments

[Fidcal]

After reading Orbweaver's thread in the Dark Radiant forum, I've been experimenting trying to get two textures to blend together. My understanding is that it is impossible except with models. But I did a test today that looks promising but probably I'm deceiving myself. I've copied the ash image, added some colour splodges and added a big fading alpha circle in it. I'm not using a bump map at the moment. My material def is:

	{
	blend blend
	map	textures/darkmod/nature/dirt/ash_test
alpha 0.9
}

You can see it is too bright, that is, self-lit, but it does fade at the edges and it does have colour and texture. What would I need to add to get it to use the local light?

 

[Fidcal]

No, I am deceiving myself. Looking closer, I don't think it is using the alpha in the image at all but is just a constant alpha throughout from the def. Might be able to use it though somehow with two or three decals on top of one another where they interface with the other texture.

[Springheel]

Using blends like that can make a texture transparent (that's how the transparent glass in the lamps works) but it is consistently transparent, and it either brightens or darkens what is behind it. It won't work for blending two regular textures.

[Fidcal]

If I remove the alpha from the def so it only uses the alpha in the image then it does fade at the edges and is totally opaque in the centre. Is there any way to control the brightness of it?

[OrbWeaver]

There's no way you can ever make a "blend blend" texture respond to lighting; it does a simple alpha blend at full image brightness. If you want the texture to be lit, you have to either use vertex blending between two diffusemap stages, or use "blend filter" which will make the blended texture darken whatever is behind it.

 

You might also want to experiment with the "translucent" global material keyword; I've never been quite sure what it does but it seems to be some kind of hybrid between alpha blending and diffusemap lighting.

[SneaksieDave]

I really hope there is at least some hacky way to do this; that would be freaking great. This and the renderer thread both have me thinking about the crumb textures again. It's really hard to believe there's not some way to fade, and instead it must be fully on or fully off. Maybe it's some magic combination of blends and translucency or using a fading placeholder decal or something. There just seems to be too much flexibility in there not to be able to do it, especially when display at least is already supported in models.

[Fidcal]

I've always been a bit disappointed with the crumb textures if you look at them too closely. Definitely better than a hard edge.

 

Pity. Seemed this was almost there. It recognizes the gradual alpha fade in the image and it adds the two textures together. Yet it can't calculate the light for the two together. Seems trivial when I consider the complexity of some of these material definitions.

 

I did succeed in getting a good blend using blend blend by carefully darkening the ash image to match the local lighting. It does work with careful placement and no moveable lighting - no fading shadow on it at all. In other words, in a constant light from one end to the other. But not really practical.

 

I'm left wondering when a gradual alpha fade in an image is ever used? It works. Does it have any application?