Way to correctly create TextureCube?


#1

Hello Urho’s community,

I just started to develop some thing with Urho but I have some issues with TextureCube.

I just want to bind one texture by side on Box model so I try this:

    Urho3D::Model *boxModel = cache->GetResource<Urho3D::Model>("Models/Box.mdl");
    
    Urho3D::TextureCube *myCube = new Urho3D::TextureCube(context_);
    Urho3D::Texture2D *leftSide = cache->GetResource<Urho3D::Texture2D>("textures/left_side.png");
    Urho3D::Texture2D *rightSide = cache->GetResource<Urho3D::Texture2D>("textures/right_side.png");
    ...

    myCube->SetData(Urho3D::CubeMapFace::FACE_POSITIVE_Z, leftSide->GetImage());
    myCube->SetData(Urho3D::CubeMapFace::FACE_NEGATIVE_Z, rightSide->GetImage());
    ...


    Urho3D::Material *cubeMat = new Urho3D::Material(context_);
    cubeMat->SetTechnique(0, cache->GetResource<Urho3D::Technique>("Techniques/Diff.xml"));
    cubeMat->SetTexture(Urho3D::TU_DIFFUSE, myCube);


    Urho3D::Node *boxNode_ = m_scene->CreateChild("Box");
    boxNode_->SetPosition(Urho3D::Vector3(17, 34, 17));
    boxNode_->SetScale(Urho3D::Vector3(1, 1, 1));

    Urho3D::StaticModel *boxObject = boxNode_->CreateComponent<Urho3D::StaticModel>();
    boxObject->SetModel(boxModel);
    boxObject->SetMaterial(cubeMat);

But I just obtain a black box (and no error has been logged), so what am I doing bad ?


#2

I don’t think TU_DIFFUSE takes cube maps, try using TU_ENVIRONMENT instead.

Also, welcome to the forums! :confetti_ball: :slightly_smiling_face:


#3

Thanks :wink:

Nop does not work.

I try cache->GetResourceUrho3D::Technique(“Techniques/DiffSkybox.xml”) it’s render but as skybox so always in backend and ignore near ligth.

So I think it need a specific tech and also shadder


#4

Ah yes, the technique for the material should be one ending in EnvCube.


#5

Envcube display me a pure reflecting geometry with no aspect of my texture.


#6

You can’t, you can render to a specific face because targets have a first-slice, but shader resources do not.

Please explain what the end result you’re trying to get is.

Why is your texture in a cubemap to begin with? A cubemap with texture-filtering is the most expensive thing you can sample so there’s nothing clever enough you could be doing to justify having a regular texture in one.

They’re also distorted so if it’s a genuine cubemap and you intend to reuse the ground or something it’s going to be warped - if that’s what you need to do than if your cubemap is in a DDS file you can load it as an Image and construct the 2d texture chain for a specific face from that as Image will have the data for all of the faces and their mip-chain.


#7

I have a collection of 2D textures and I just want to display a cube with each side have a specified texture and the texture in side can be changed during the game and texture ca be also use in other objects so that’s why I don’t want to use a unique texture with 6 sides texture. I used TextureCube because an object have a material and it’s material have just one texture. Maybe I don’t use the best way and maybe I don’t need to use TextureCube (but it work like a dictionary with each side is affected to a texture so I tried to use it).


#8

What you describe is what Texture2DArray is for. You still need to create a shader to accept the index and the texture-array. The included shaders don’t use it.

<texturearray> <!-- Texture2DArray::Load doesn't actually process the root element -->
    <layer name="Textures/Dirt.dds" />
    <layer name="Textures/Grass.dds" />
    <layer name="Textures/Stone.dds" />
    <layer name="Textures/Snow.dds" />
    <layer name="Textures/Gravel.dds" />
    ... repeat ad infinitum ...
</texturearray>

They have to be the exact same format (RGB/RGBA/etc).


#9

Have you a example of the shader I need?


#10

In that case you may want to make a cube with 6 geometries/materials after all, one for each side. You could clone the material and then set a different texture.
You can reuse the material by simply passing its pointer to the other objects


#11

Ask in a few days, if you can’t work that out on your own you’re in over your head.

You just add a #define, the sampler for the array, and an additional material variable for the texture-index. Where the desired texture is sampled you wrap it in a #ifdef and do the appropriate array lookup. Brain filtered out that you’re just mapping cube faces.

You’re not going to see any substantial performance increase without C++ side engine changes unless you’re just going to index off of the instance id (which you can only do on static models, and it won’t be stable) - as you’ll need a unique material per index in the array, which will batch-out to being almost the same as separate textures.

Edit: wait what?! A cube? You can use UDIM and just modulo the array index.


#12

Thanks for your help, I will try and come back later if needed.


#13

We proceed in an other way because of some optimization needed we split cubes into 6 textures and apply greedy meshing algorithm to downsize number of vertices.

But many thanks for your explanations.