Doom3world

So I've finally worked out a method to create a proper seamless looping image sequence for water. Here's the normal map...



Obviously you can't use GIF in game so here's a PK4 with the TGA image sequence and a material shader to demonstrate how to cycle through the sequence...

http://temp-share.com/show/KdPf3ip3h

The sequence itself looks good but I'm not happy with the limitations of the current renderer so let's see what you guys can do with it.

This was done almost entirely with Blender and I'll elaborate on the process if there is interest.

Very cool. This definitely looks like a fluid / liquid!

Cool stuff Rich. I think The Dark Mod crew will appreciate this one too

Very nice, Rich! And there is indeed interest in your process elaboration...

@LDAsh:

What you're looking at is basically Blender's ocean simulation. I found out recently that it is seamless and can bake a sequence of normal maps. I ran into some complications however.

The baked images are stored as OpenEXR files. It's easy enough to find a tool that will allow you to convert to Targa but I was hoping for batch conversion. Imagemagick will do the job but it doesn't support OpenEXR out of the box. To gain that functionality you're required to compile your own binary and being a Windows user and not much of a coder; I wasn't having that. In addition the normal maps didn't appear to be in tangent space. I was seeing lots of green and red but no blue.

The way I got around these problems was to bake a normal map the old fashioned way. Subdivide a plane a few times and apply the ocean simulation as a displacement. That yields a high polygon model. Create a second plane of equal size for the low polygon model, position it above the high polygon model, and bake. The only downside here was that I had to advance the timeline and bake each frame manually. I probably could have wrote a python script to automate this but it wasn't too much trouble.

This worked but there was a catch. The displacement is three dimensional meaning some parts of the high poly model were outside the projection area. The fix for this was to apply two array modifiers to the high polygon model to create a larger but repeating "ocean". I repositioned my low polygon object and baked.

Now to make the sequence loop. The trick here is simple and old school. It's basically a cross fade and since Blender has a built-in video editor you don't have to exit the program. You take the sequence and cut it in half. This middle point is now the beginning of one clip and the end of another. By overlaying the two clips and cross fading between them the jarring ends disappear.

The last problem was one I had encountered before in the past but it had slipped my mind. Blender's normal maps need to have the green channel inverted in order to work properly in Doom 3. Luckily Imagemagick can do that and I don't need to build a new executable for it.

@nbohr1more

Would you believe I tested this in TDM? It looks good if the water is opaque. But if the water is transparent it looks almost identical to the existing textures. You guys are welcome to it though.

Did you try using the generated normalmaps for refraction ?

Something like that :

Yes. I tried it with heathaze. It looks almost identical to a scrolling texture so you don't really gain anything there.

Would this be good for pools of blood?

Nice work rich,
It looks like it would be ideal for lava pools, so I'll give that a try.

I tried a similar approach for creating ripples around the player's legs in water (animated expanding circle as a specular map), but it didn't work out in practice because overlapping ripples became overbright. I must revisit that problem...

I played around with this stuff last year, to make better stream textures. While I cant seem to remember what I did with the textures/script/material, I remember that when using the animated normalmap + refraction, it only looked any good with quite a lot of specular on it to bring out the details.

I was generating the strip texture from script, as animating with multiple files can cause trouble, as well as being slightly cheaper. Just using a scale with instant jump worked quite well to move along the strip.

Edit : Oh, found the material and two textures

How do you handle tiling or does that just naturally work out since each frame is nearly identical to the next?

Heh, I cant remember at all - I don't see why it wouldn't work, the ambient stage is uniform, I think that's about the only thing that might not tile if it included a real normalmap.

I never really worked out how to generate nice tiles which had current and minor ripples, to look like a stream; then I got sidetracked by something else.