LibGDX - 使用Modelbuilder.createBox将单个纹理映射到框的每个面

Question

我有以下代码片段生成3D多维数据集:

ModelBuilder modelBuilder = new ModelBuilder();

box = modelBuilder.createBox(2f, 2f, 2f,
                new Material(TextureAttribute.createDiffuse(AssetLoader.tr[0])),
                VertexAttributes.Usage.Position | VertexAttributes.Usage.Normal | VertexAttributes.Usage.TextureCoordinates
        );

到现在为止还挺好.问题是立方体的所有面使用相同的纹理,而我想要的是Assetloader.tr [],它是一个数组,每个面上分别出现6个单独的纹理.

我试过了

box.nodes.get(0).parts.get(0).material.set(new Material(TextureAttribute.createDiffuse(AssetLoader.tr[0])));
box.nodes.get(0).parts.get(1).material.set(new Material(TextureAttribute.createDiffuse(AssetLoader.tr[1])));
...

但不知何故,文档没有给我任何关于如何正确地做到这一点的提示.我有点被困在这里.

Answer 1

要记住几个注意事项.首先请务必仔细阅读:https://github.com/libgdx/libgdx/wiki/ModelBuilder%2C-MeshBuilder-and-MeshPartBuilder.

其次,尽量避免使用这些ModelBuilder#createXXX方法.它们只是调试和测试目的的捷径.如果你看看它背后的代码,你会发现它非常简单:

modelBuilder.begin();
modelBuilder.part("box", GL20.GL_TRIANGLES, 
        VertexAttributes.Usage.Position | VertexAttributes.Usage.Normal | VertexAttributes.Usage.TextureCoordinates,
        new Material(TextureAttribute.createDiffuse(AssetLoader.tr[0])))
    .box(2f, 2f, 2f);
box = modelBuilder.end();

正如您所看到的,这会为整个框创建一个单独的部分,因此尝试访问第二部分(就像您在示例中所做的那样)将无法正常工作.但是因为你想为每张脸使用不同的材质,你需要为每张脸创造一个部分.

int attr = VertexAttributes.Usage.Position | VertexAttributes.Usage.Normal | VertexAttributes.Usage.TextureCoordinates;
modelBuilder.begin();
modelBuilder.part("front", GL20.GL_TRIANGLES, attr, new Material(TextureAttribute.createDiffuse(AssetLoader.tr[0])))
    .rect(-2f,-2f,-2f, -2f,2f,-2f,  2f,2f,-2, 2f,-2f,-2f, 0,0,-1);
modelBuilder.part("back", GL20.GL_TRIANGLES, attr, new Material(TextureAttribute.createDiffuse(AssetLoader.tr[1])))
    .rect(-2f,2f,2f, -2f,-2f,2f,  2f,-2f,2f, 2f,2f,2f, 0,0,1);
modelBuilder.part("bottom", GL20.GL_TRIANGLES, attr, new Material(TextureAttribute.createDiffuse(AssetLoader.tr[2])))
    .rect(-2f,-2f,2f, -2f,-2f,-2f,  2f,-2f,-2f, 2f,-2f,2f, 0,-1,0);
modelBuilder.part("top", GL20.GL_TRIANGLES, attr, new Material(TextureAttribute.createDiffuse(AssetLoader.tr[3])))
    .rect(-2f,2f,-2f, -2f,2f,2f,  2f,2f,2f, 2f,2f,-2f, 0,1,0);
modelBuilder.part("left", GL20.GL_TRIANGLES, attr, new Material(TextureAttribute.createDiffuse(AssetLoader.tr[4])))
    .rect(-2f,-2f,2f, -2f,2f,2f,  -2f,2f,-2f, -2f,-2f,-2f, -1,0,0);
modelBuilder.part("right", GL20.GL_TRIANGLES, attr, new Material(TextureAttribute.createDiffuse(AssetLoader.tr[5])))
    .rect(2f,-2f,-2f, 2f,2f,-2f,  2f,2f,2f, 2f,-2f,2f, 1,0,0);
box = modelBuilder.end();

但是,为每个面部设置一个部分确实意味着每个面部的渲染调用.确保所有TextureRegions共享相同的纹理并使用它更具高效性:

int attr = VertexAttributes.Usage.Position | VertexAttributes.Usage.Normal | VertexAttributes.Usage.TextureCoordinates;
modelBuilder.begin();
MeshPartBuilder mpb = modelBuilder.part("box", GL20.GL_TRIANGLES, attr, new Material(TextureAttribute.createDiffuse(AssetLoader.tr[0].getTexture())));
mpb.setUVRange(AssetLoader.tr[0]);
mpb.rect(-2f,-2f,-2f, -2f,2f,-2f,  2f,2f,-2, 2f,-2f,-2f, 0,0,-1);
mpb.setUVRange(AssetLoader.tr[1]);
mpb.rect(-2f,2f,2f, -2f,-2f,2f,  2f,-2f,2f, 2f,2f,2f, 0,0,1);
mpb.setUVRange(AssetLoader.tr[2]);
mpb.rect(-2f,-2f,2f, -2f,-2f,-2f,  2f,-2f,-2f, 2f,-2f,2f, 0,-1,0);
mpb.setUVRange(AssetLoader.tr[3]);
mpb.rect(-2f,2f,-2f, -2f,2f,2f,  2f,2f,2f, 2f,2f,-2f, 0,1,0);
mpb.setUVRange(AssetLoader.tr[4]);
mpb.rect(-2f,-2f,2f, -2f,2f,2f,  -2f,2f,-2f, -2f,-2f,-2f, -1,0,0);
mpb.setUVRange(AssetLoader.tr[5]);
mpb.rect(2f,-2f,-2f, 2f,2f,-2f,  2f,2f,2f, 2f,-2f,2f, 1,0,0);
box = modelBuilder.end();

虽然这可能对您有所帮助,但您应该重新考虑您的方法.正如您所看到的,通过代码创建模型可能会非常快速地变得混乱.而且,在大多数情况下,为盒子创建单个模型远非最佳,除非您的目标是仅渲染单个框而不仅仅是框.而是使用建模应用程序来创建模型.有关详细信息,请访问我的博客http://blog.xoppa.com/.如果您真的想自己修改部件,那么请务必至少阅读并包括"幕后"教程.