Hardware Terrain Splatting

Momoko_Fan · August 4, 2007, 8:57pm

Original jME low-res software splatting with detail texture

Similar configuration: Hardware splatting with trilinear filtering & 2 pass rendering

info, screenshot & download

Dosfish · August 4, 2007, 10:39pm

Cool, looks useful, thanks.

HamsterofDeath · August 5, 2007, 12:56am

adding to own terrain rendering asap

where is the lighmap generator? i want to use it

hevee · August 5, 2007, 7:51am

Nice! Have you seen my own, similar attempt? http://www.jmonkeyengine.com/jmeforum/index.php?topic=4146.0

I like the fact that your's is applied as a render pass a bit better, though, but won't be able to switch over soon because I currently have my alpha maps in greyscale, not alpha channels. Plus I need an option to update alpha maps (splat painting), but that should be trivial to add.

GLSL doesn't work for me, while it does well in my own version. I'll try to look into that later, and provide a fix if possible.

Momoko_Fan · August 5, 2007, 12:48pm

Nice! Have you seen my own, similar attempt?

Yes, I have seen it, but it uses GLSL only, which means that it doesn't support fixed-pipeline effects (like fog), it is a lot slower than regular rendering, and can only handle as many textures as the card supports, those kind of limitations are not acceptable (at least for me).
I have implemented GLSL in my system, thinking that it would improve performance if many tiles are used (less passes), but it seems like I was wrong, fixed-pipeline is the way to go here.

but won't be able to switch over soon because I currently have my alpha maps in greyscale, not alpha channels.

With this system, you can try uploading your grayscale textures as ALPHA8 and then it would work. To update the splat textures, you could add an refresh method to the pass which would delete the alphamaps from the TextureStates.

where is the lighmap generator? i want to use it

I am not going to release it, yet. It is unfinished. I can say however, that using a pregenerated alphamap can triple the rendering speed of terrain.

Momoko_Fan · August 5, 2007, 2:07pm

My card is Geforce FX 5200, which is (to my knowledge) the first consumer card to support programmable shaders, I guess that it was not yet fully optimized for programming.

Hm, in that case, it would be best to ask the user if to use shaders or not. If many tiles are used, then it would be definetly better to use shaders to have less passes and thus increase performance.

Great, I'll definitely try that!

Just letting you know, ALPHA8 is missing from jME as of right now. You need to add it by yourself to the Image and LWJGLTextureState classes.

HamsterofDeath · August 5, 2007, 2:10pm

i tried using the renderpass for my terrain, but it looks rather crappy. like on the second screenshot, instead of texture 1 <-> texture 2, it renders texture 1 <-> white <-> texture 2. i thought this was intended, but i guess it's a "hole" (sum of all alpha values at a point is not 1) in the alpha maps. after they have been generated, you should check for values < 1 and add the apropriate values to the alpha maps.

also, the terrain started to look too regular and boring because my greyscale-detailtextures are now missing (i used 3 at different scalings which made the terrain look non-regular).

Momoko_Fan · August 5, 2007, 2:15pm

All the problems you mentioned have nothing to do with the library.

ike on the second screenshot, instead of texture 1 <-> texture 2, it renders texture 1 <-> white <-> texture 2.

The white in the 2nd screenshot is the highest.jpg texture, which is completely white (to represent snow I guess)

i guess it's a "hole" (sum of all alpha values at a point is not 1) in the alpha maps. after they have been generated, you should check for values < 1 and add the apropriate values to the alpha maps.

You need to input the correct values for the alphamap generator, so that no height ranges intersect too much.

I guess it is possible to normalize the alphamaps to get correct results, but that is not the purpose of this system.

HamsterofDeath · August 5, 2007, 2:21pm

what are the "correct" values? to get a constant opaque terrain?

another idea: could i render my own old terrain above yours using dst alpha as the blending function (or below -> render it first) to fill the holes?

this way i'd use your method to add high detal textures for things like roads or high slopes and use my own rendering for the usual parts

Momoko_Fan · August 5, 2007, 10:24pm

what are the "correct" values? to get a constant opaque terrain?

The sum alpha for all alphamaps at any given point must be 1.0

another idea: could i render my own old terrain above yours using dst alpha as the blending function (or below -> render it first) to fill the holes?
this way i'd use your method to add high detal textures for things like roads or high slopes and use my own rendering for the usual parts

Sure, do whatever you want.

HamsterofDeath · August 6, 2007, 7:10am

The sum alpha for all alphamaps at any given point must be 1.0

i know. but which min/center/max-values should i use to make sure the sum is one?
these do not work with your method, but give perfect results with the jme's texturegenerator:

texture1.url=visual/landscape/grass_ground2.jpg texture1.from=0 texture1.fullat=0 texture1.to=60 texture2.url=visual/landscape/moss11.jpg texture2.from=0 texture2.fullat=60 texture2.to=120 texture3.url=visual/landscape/pebbles9.jpg texture3.from=60 texture3.fullat=120 texture3.to=180 texture4.url=visual/landscape/rock_moss.jpg texture4.from=120 texture4.fullat=180 texture4.to=240 texture5.url=visual/landscape/SnowTexture.jpg texture5.from=180 texture5.fullat=255 texture5.to=255

for comparison:
new: http://img337.imageshack.us/my.php?image=fanrenderingls7.jpg
old: http://img356.imageshack.us/my.php?image=jmerenderingvq7.jpg

Momoko_Fan · August 6, 2007, 3:54pm

To be honest, I don't really know. The height-based alphamap generator was made only so that no external alphamaps are used in the test. I am using pregenrated alphamaps and so I don't have any of those problems.

sarcius · August 6, 2007, 4:49pm

Very cool! I can't wait to check out the source and try it out!

HamsterofDeath · August 6, 2007, 5:54pm

seems like i'll have to make my own. SO BE IT!

Momoko_Fan · August 7, 2007, 8:29pm

seems like i'll have to make my own. SO BE IT!

I don't see a reason for that. The test uses the procedural alpha generator and it works fine, the system does what's it suppose to do perfectly. The problem is clearly on your side.
EDIT: By the way, I did not use a license for this code. You could import it into jME's CVS if you want.

Momoko_Fan · August 12, 2007, 2:31am

Momoko_Fan · August 16, 2007, 4:46pm

It seems to me that implementing render passes is best done through the scene graph architecture, by extending SceneElement, which also provides bound checking and locking capabilities. It also allows the pass to be used within other passes such as the water render pass.

I might try to reimplement this system as a SceneElement at some point.

MrCoder · August 17, 2007, 8:31am

Have you looked at PassNode and TestPassNode?

Momoko_Fan · August 17, 2007, 9:55pm

Very useful, and saves me work. Thanks.

HamsterofDeath · August 18, 2007, 10:06pm

i don't quite understand how a renderpass works, so i have no ida how to do this:

render my terrain the old fashioned way
use momokos pass to add more detail at some spots
render another greyscale-texture on top off all this (lightmap/noisemap)

1+3 are being done now using detail textures of different scalings, but when i use the momoko-pass, my terrain is not visible - everything is white.