Transparency in terrain

[Priyank.Jain2]

Hi,

 

I want to set some portion of terrain object as transparent. In our previous version(2014-06-04) we were adding surface material and than use "setMaterialDiffuseScale" to control the visibility (we are using custom material for fragment base ambient shader to use diffuse alpha).

 

Now with Unigine 2.3.1 instead of materials you have to add overlay layers and use "setMaterialAlbedoScale" for same thing. I have tried same approach on a sample but unable to make the terrain transparent.

 

Basically we want to have some x-ray kind of functionality where in we can see what is underneath the terrain.

 

How can we achieve that?

[silent]

Hi Priyank,

 

There is no way to make terrain transparent out of the box. Generally, adding an ability to make terrain's surfaces transparent will result in huge performance drop.

 

For your use-case you can try to use Camera class (just put it under terrain and render image to texture) and use this texture in decal that will be projected onto terrain or any other surface. 

The second solution will be to use holes texture to remove terrain geometry in the specific spot (not sure if that will fit your needs).

 

You also can try to check how Alpha blend is done for mesh_base material and try to write custom shader for terrain that will render it in forward pass, but with transparency (will cause performance degradation).

 

Thanks!

[Priyank.Jain2]

Thanks for the pointers,

 

This is the same way we have handled transparency in previous implementation(by editing the existing ambient shader).

<shader pass="ambient" object="terrain"
defines="BASE_AMBIENT,AMBIENT"
receive_world_shadow_defines=",SHADOW"
terrain_defines="PATCH,0,0"
ambient="1"
detail_0_defines=",DETAIL_0_OVERLAY,DETAIL_0_OVERLAP"
detail_1_defines=",DETAIL_1_OVERLAY,DETAIL_1_OVERLAP"
detail_2_defines=",DETAIL_2_OVERLAY,DETAIL_2_OVERLAP"
detail_3_defines=",DETAIL_3_OVERLAY,DETAIL_3_OVERLAP"
triplanar_defines=",PATCH_TRIPLANAR"
ambient_light_defines=",AMBIENT_LIGHT"
vertex="core/shaders/default/terrain/vertex_base.shader"
fragment="our_own_shader"/>

So now you mean same thing should work here as well?

 

Is there any sample which I can refer?

[silent]

Hi Priyank,

 

There is no sample available. Terrain out of the box is not supporting any kind of transparency in shader - you have to add missing code similar that we have right now in other materials with transparency (for example, mesh_base).

 

That code from old shaders will not work.

[Priyank.Jain2]

Thanks,

 

I have tried the same approach but looks like ambient pass for terrain needs some other flags/states to be set.

 

Please check attached test project where in I have used my test ambient shader with hard-coded color values, but that is not making any difference when I chose terrain transparency as "alpha blend" or "Custom" (with src alpha and one minus src alpha)

 

Let me know if I am doing something wrong or missing something.

 

Note: Attached sample doesn't have core.ung, editor.ung and Qt5CoreUnigine_x64.dll

terrain_u2.zip

[silent]

Hi Priyank,

Thank you for the test scene!

The thing is there is no alpha blend or any alpha transparency support in the default fragment shader of terrain (data/core/shaders/terrain/fragment/*), so enabling states in material file will not lead to the different results.

 

I'm afraid you have to write your own terrain fragment shader with alpha blend (with all light passes, ambient pass and so on).

 

Thanks!

[Priyank.Jain2]

Ok, So in the test scene I have used the default terrain fragment shader and in the ambient pass tried to set some hard coded value to OUT_color,  just for testing but that also did not worked.

 

Can you please help in understanding the most hacky way of doing that(atleast for testing purpose)? What are the shaders and passes I can reuse from "terrain_base" ?

[Akshay.Patil]

Hello ,

1 ) 

We have created our own material for terrain derived from "terrain_base" (unigine_2_3_1\data\core\materials\default\unigine_terrain.mat)

And we have disabled the deferred pass and enabled the ambient pass and done few changes to "terrain_base" so that we get values for states

subtract_layers, material_detail, material_roughness, material_normal, num_materials, num_layers in ambient pass by modifying its pass_defines attribute

 

On shader side we are use deffered shader as it is (unigine_2_3_1\data\core\shaders\terrain\vertex\deferred.vert)

and we are using the fragment shader (unigine_2_3_1\data\core\shaders\terrain\fragment\deferred.frag)

with a bit of modification as we can not write to gbuffer i am skipping the setGbuffer.

 

So we are exactly doing the same thing as in deferred shader

and trying to output the color myself by doing some light computations in our shader but they are not working good (Not getting exact lighting as we have in deferred shader)

 

Can you help us  which UUSL functions should we use in our ambient shader  to match the lighting in deferred shader ?? 

 

 

2)

We are setting up terrain through unigine script only

But i am having bit difficulty because of TextureArray functionality

 

We are setting up layers and adding materials through API only.

But they does not seem to work at all, Looks just the albedo color for material is getting applied and not the textures

 

But when we created the AlbedoTextureArray using editor and applied it to our terrain through API again , strangely things started working.

Looks like when we just add materials and layers , AlbedoTextureArray is not getting created internally .

Is it a known issue or Am I missing something ?

 

3) Also why we need to define AlbedoTextureArray  when we are creating layers and materials ? 

[Akshay.Patil]

Hello ,

I am using the sample attached by priyank in folder terrain_u2.zip

 

But i am facing camera related issues.

If i launch the editor and use Editor camera i am able to save its postion and restore back on same position 

But I am not able to save/ restore game camera position . I am using camera lock unlock sequence as mentioned in manual

Is there any file where this settings are saved ?

[silent]

Hi Akshay,

 

Game camera is controlled only via code (engine.game.getPlayer() / engine.game.setPlayer()).

[Akshay.Patil]

Thanks , i am having one additional problem i am not able to navigate inside standalone app for terrain_u2 ,

while the same is possible in the app i created fresh using brower

[silent]

Please, check the sample code and modify it to be like the other samples. Or ask Priyank to modify it for you :)