libGDX中的慢模型批处理渲染

Question

我有一个问题是，是否有一种特殊的模式可以在libGDX中对模型进行分组。我创建了一个实现ApplicationListener的简单类来显示我的问题。我正在使用每晚构建的libGDX。

我读了两个使用相同纹理的不同模型。该应用程序分别呈现每种类型的250个模型。这就是呈现代码的部分：

  mModelBatch.begin(camera);
  for(int y=0; y<50; y++)
  {
     for(int x=-5; x<5; x++)
     {
        ModelInstance instance;
        if(x%2 == 0) instance = modelInstance1;
        else instance = modelInstance2;

        instance.transform.setToTranslation(x, 0, -y);
        mModelBatch.render(instance);
     }

  }

  mModelBatch.end(); 

我试图找到一个好的解决方案，所以我写了另一个测试代码：

public void getRenderables(Array<Renderable> renderables, Pool<Renderable> pool)
{
  for(int y=0; y<50; y++)
  {
     for(int x=-5; x<5; x++)
     {
        ModelInstance instance;
        if(x%2 == 0) instance = modelInstance1;
        else instance = modelInstance2;

        instance.transform.setToTranslation(x, y%3, -y);

        Renderable renderable = pool.obtain();
        renderable = instance.getRenderable(renderable);
        renderables.add(renderable);
     }
  }

}

我使用它，如下所示：

mModelBatch.begin(camera);      
mModelBatch.render(testRenderProvider);
mModelBatch.end();

然而它仍然给了我13 FPS。 同时，为了进行另一次测试，我在搅拌机中创建了与之前程序中相同的地图。接下来，我将所有内容分组到一个对象中（没有任何其他版本）。这样我创建了一个大小近1MB的BIG对象，可以在blender的截图中看到。

我改变了测试程序，它只绘制了一个BIG对象：

mModelBatch.begin(camera);
      modelInstance1.transform.setToTranslation(0, 0, 0);
      mModelBatch.render(modelInstance1);
mModelBatch.end();

接下来我做的是我在手机上启动了程序（Sony XPeria Mini Pro - 和以前一样）和iPod 5g，我有... 60 FPS！

是否可以只用一次绘制调用来渲染所有内容？

Answer 1

问题解决了！我在低端移动设备上实现了60 FPS。游戏顺利进行。我发现了如何将多个网格合并到一个网格中，以便可以使用VBO机制。 libGDX中存在一个错误，导致Mesh复制方法无法用于多个网格。在更改之后，地图被划分为小扇区。每个扇区由具有相同z轴值的网格组成，如下图所示：

VBO机制是非常有限的，因此一次可以绘制的顶点不多，这就是扇区必须相当小的原因。 必须编写新的渲染器才能正确处理渲染。并且渲染器的各部分动态地合并网格（没有任何单独的工具，例如.blender）。

public static Mesh mergeMeshes(AbstractList<Mesh> meshes, AbstractList<Matrix4> transformations)
{
    if(meshes.size() == 0) return null;

    int vertexArrayTotalSize = 0;
    int indexArrayTotalSize = 0;

    VertexAttributes va = meshes.get(0).getVertexAttributes();
    int vaA[] = new int [va.size()];
    for(int i=0; i<va.size(); i++)
    {
        vaA[i] = va.get(i).usage;
    }

    for(int i=0; i<meshes.size(); i++)
    {
        Mesh mesh = meshes.get(i);
        if(mesh.getVertexAttributes().size() != va.size()) 
        {
            meshes.set(i, copyMesh(mesh, true, false, vaA));
        }

        vertexArrayTotalSize += mesh.getNumVertices() * mesh.getVertexSize() / 4;
        indexArrayTotalSize += mesh.getNumIndices();
    }

    final float vertices[] = new float[vertexArrayTotalSize];
    final short indices[] = new short[indexArrayTotalSize];

    int indexOffset = 0;
    int vertexOffset = 0;
    int vertexSizeOffset = 0;
    int vertexSize = 0;

    for(int i=0; i<meshes.size(); i++)
    {
        Mesh mesh = meshes.get(i);

        int numIndices = mesh.getNumIndices();
        int numVertices = mesh.getNumVertices();
        vertexSize = mesh.getVertexSize() / 4;
        int baseSize = numVertices * vertexSize;
        VertexAttribute posAttr = mesh.getVertexAttribute(Usage.Position);
        int offset = posAttr.offset / 4;
        int numComponents = posAttr.numComponents;

        { //uzupelnianie tablicy indeksow
            mesh.getIndices(indices, indexOffset);
            for(int c = indexOffset; c < (indexOffset + numIndices); c++)
            {
                indices[c] += vertexOffset;
            }
            indexOffset += numIndices;
        }

        mesh.getVertices(0, baseSize, vertices, vertexSizeOffset);
        Mesh.transform(transformations.get(i), vertices, vertexSize, offset, numComponents, vertexOffset, numVertices);
        vertexOffset += numVertices;
        vertexSizeOffset += baseSize;
    }

    Mesh result = new Mesh(true, vertexOffset, indices.length, meshes.get(0).getVertexAttributes());
    result.setVertices(vertices);
    result.setIndices(indices);
    return result;
} 

    public static Mesh copyMesh(Mesh meshToCopy, boolean isStatic, boolean removeDuplicates, final int[] usage) {
    // TODO move this to a copy constructor?
    // TODO duplicate the buffers without double copying the data if possible.
    // TODO perhaps move this code to JNI if it turns out being too slow.
    final int vertexSize = meshToCopy.getVertexSize() / 4;
    int numVertices = meshToCopy.getNumVertices();
    float[] vertices = new float[numVertices * vertexSize];
    meshToCopy.getVertices(0, vertices.length, vertices);
    short[] checks = null;
    VertexAttribute[] attrs = null;
    int newVertexSize = 0;
    if (usage != null) {
        int size = 0;
        int as = 0;
        for (int i = 0; i < usage.length; i++)
            if (meshToCopy.getVertexAttribute(usage[i]) != null) {
                size += meshToCopy.getVertexAttribute(usage[i]).numComponents;
                as++;
            }
        if (size > 0) {
            attrs = new VertexAttribute[as];
            checks = new short[size];
            int idx = -1;
            int ai = -1;
            for (int i = 0; i < usage.length; i++) {
                VertexAttribute a = meshToCopy.getVertexAttribute(usage[i]);
                if (a == null)
                    continue;
                for (int j = 0; j < a.numComponents; j++)
                    checks[++idx] = (short)(a.offset/4 + j);
                attrs[++ai] = new VertexAttribute(a.usage, a.numComponents, a.alias);
                newVertexSize += a.numComponents;
            }
        }
    }
    if (checks == null) {
        checks = new short[vertexSize];
        for (short i = 0; i < vertexSize; i++)
            checks[i] = i;
        newVertexSize = vertexSize;
    }

    int numIndices = meshToCopy.getNumIndices();
    short[] indices = null; 
    if (numIndices > 0) {
        indices = new short[numIndices];
        meshToCopy.getIndices(indices);
        if (removeDuplicates || newVertexSize != vertexSize) {
            float[] tmp = new float[vertices.length];
            int size = 0;
            for (int i = 0; i < numIndices; i++) {
                final int idx1 = indices[i] * vertexSize;
                short newIndex = -1;
                if (removeDuplicates) {
                    for (short j = 0; j < size && newIndex < 0; j++) {
                        final int idx2 = j*newVertexSize;
                        boolean found = true;
                        for (int k = 0; k < checks.length && found; k++) {
                            if (tmp[idx2+k] != vertices[idx1+checks[k]])
                                found = false;
                        }
                        if (found)
                            newIndex = j;
                    }
                }
                if (newIndex > 0)
                    indices[i] = newIndex;
                else {
                    final int idx = size * newVertexSize;
                    for (int j = 0; j < checks.length; j++)
                        tmp[idx+j] = vertices[idx1+checks[j]];
                    indices[i] = (short)size;
                    size++;
                }
            }
            vertices = tmp;
            numVertices = size;
        }
    }

    Mesh result;
    if (attrs == null)
        result = new Mesh(isStatic, numVertices, indices == null ? 0 : indices.length, meshToCopy.getVertexAttributes());
    else
        result = new Mesh(isStatic, numVertices, indices == null ? 0 : indices.length, attrs);
    result.setVertices(vertices, 0, numVertices * newVertexSize);
    result.setIndices(indices);
    return result;
}

这对于试图在libGDX中编写自己的3D游戏的人来说非常有用。如果没有这种机制，写一些比一些模型更复杂的东西是不可能的。