android – 如何使用Project Tango实验网格化API

我为我的长篇文章提前道歉.

我的目的是为Project Tango Yellowstone设备创建一个网格化应用程序,以创建建筑内部的3D地图.我打算利用最近版本的tango-examples-c代码中添加的实验网格API.

我使用point-cloud-jni-example(turing)作为起点,到目前为止已完成以下操作：

>在point_cloud_app.cc中设置config_experimental_enable_scene_reconstruction tango配置参数(参见docs)

// Enable scene reconstruction
ret = TangoConfig_setBool(tango_config_, 
        config_experimental_enable_scene_reconstruction", true);
    if (ret != TANGO_SUCCESS) {
        LOGE("PointCloudApp:         config_experimental_enable_scene_reconstruction() Failed"
            "with error code: %d", ret);
        return ret;
}

>在TangoJNINative.java中添加了extractMesh本机方法

// Extracts the full mesh from the scene reconstruction.
public static native float extractMesh();

>将匹配的extractMesh函数添加到jni_interface.cc

JNIEXPORT void JNICALL
Java_com_projecttango_experiments_nativepointcloud_TangoJNINative_extractMesh(
jnienv*, jobject) {
    app.ExtractMesh();
}

>在point_cloud_app.cc中添加了ExtractMesh方法

void PointCloudApp::ExtractMesh() {
// see line 1245 of tango_client_api.h
    mesh_ptr = new TangoMesh_Experimental();
    TangoService_Experimental_extractMesh(mesh_ptr);
    mesh = *mesh_ptr;
    LOGE("PointCloudApp: num_vertices: %d", mesh.num_vertices);

    float float1, float2, float3;
    float1 = mesh.vertices[1][0];
    float2 = mesh.vertices[1][1];
    float3 = float1 + float2;  // these lines show I can use the vertex data
    LOGE("PointCloudApp: First vertex, x: %f", mesh.vertices[1][0]);  // this line causes app to crash; printing the vertex data seems to be the problem
}

>将TangoMesh_Experimental声明添加到point_cloud_app.h

// see line 1131 of tango_client_api.h
TangoMesh_Experimental* mesh_ptr;
TangoMesh_Experimental mesh;

>添加了一个额外的按钮来调用extractMesh本机方法. (没有显示这个,因为它非常简单)

作为参考,这里是API的TangoMesh_Experimental Struct：

    // A mesh, described by vertices and face indices, with optional per-vertex
    // normals and colors.
    typedef struct TangoMesh_Experimental {
    // Index into a three-dimensional fixed grid.
    int32_t index[3];

    // Array of vertices. Each vertex is an {x, y, z} coordinate triplet, in
    // meters.
    float (*vertices)[3];

    // Array of faces. Each face is an index triplet into the vertices array.
    uint32_t (*faces)[3];

    // Array of per-vertex normals. Each normal is a normalized {x, y, z} vector.
    float (*normals)[3];

    // Array of per-vertex colors. Each color is a 4-tuple of 8-bit {R, G, B, A}
    // values.
    uint8_t (*colors)[4];

    // Number of vertices, describing the size of the vertices array.
    uint32_t num_vertices;

    // Number of faces, describing the size of the faces array.
    uint32_t num_faces;

    // If true, each vertex will have an associated normal. In that case, the
    // size of the normals array will be equal to num_vertices. Otherwise, the
    // size of the normals array will be 0.
    bool has_normals;

    // If true, each vertex will have an associated color. In that case, the size
    // of the colors array will be equal to num_vertices. Otherwise, the size of
    // the colors array will be 0.
    bool has_colors;
    } TangoMesh_Experimental;

我目前对这个结构的理解是：

> float中的三个指针(*顶点)[3];指向三个内存块开头的地址,用于网格顶点的x,y和z坐标(法线和颜色颜色也是如此).特定顶点由在三个数组中的特定索引处找到的x,y和z分量组成.
>类似地,uint32_t(* faces)[3]数组有三个指针指向三个内存块的开头,但是这里有一组特定的三个元素,而是包含指示哪三个顶点的索引号(来自顶点数组(每个都有)三个坐标))弥补那张脸.

当前状态是我能够提取网格,并将其中的一些打印到控制台,然后崩溃没有错误

PointCloudApp: PointCloudApp: num_vertices: 8044

如果我省略了我在point_cloud_app.cc(上面的#4)中添加的最后一行,则应用程序不会崩溃.我能够访问顶点数据并使用它执行某些操作,但使用LOGE打印它会导致10次崩溃.偶尔,它会正确打印值而不会崩溃.顶点数据是否有洞或无效值？

我已经尝试将j_I中的test_float返回给java,但是当我尝试这样做时它又崩溃了.

建议？

解决方法:

顶点是一个动态点数组,其中每个点都是一个浮点数[3].试试这个例子：

for (int i = 0; i < mesh.num_vertices; ++i) {
  printf("%d: x=%f y=%f z=%f\n", i, mesh.vertices[i][0], 
      mesh.vertices[i][1], mesh.vertices[i][2]);
}

如果你看一下内存布局,那就是x0 y0 z0 x1 y1 z1等,每个都是浮点数.

android – 如何使用Project Tango实验网格化API

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