cJSON 的简单应用——保存/解析 Shader 参数 【代码示例】

自定义的 Shader 程序结构体：

struct ShaderProgram
{
    struct Path
    {
        char *vertex_shader_path;
        char *fragment_shader_path;
    } path;

    struct FragmentShaderUniformLocation
    {
        char *channel_0;
        char *channel_1;
        char *global_time;
        char *resolution;
    } fsul;

};

入口函数：

int main()
{
#ifdef TOFILE
    createObjects();
#else
    parseFile("result.txt");
#endif
    return 0;
}

创建 (Shader Program) JSON 对象并保存为 txt 的函数：

void createObjects()
{
#if MUL
  ShaderProgram sp[2] =
  {
    {
      { "../Shader/vs_0.glsl", "../Shader/fs_0.glsl" },
      { "iChannel0", "iChannel1", "iGlobalTime", "iResolution" }
    },  // sp[0]

    {
      { "../Shader/vs_1.glsl", "../Shader/fs_1.glsl" },
      { "iChannel0", "iChannel1", "iGlobalTime", "iResolution" }
    } // sp[1]
  };
#else
  ShaderProgram sp =
  {
    { "../Shader/vs_0.glsl", "../Shader/fs_0.glsl" },
    { "iChannel0", "iChannel1", "iGlobalTime", "iResolution" }
  };

#endif

  cJSON *root = cJSON_CreateArray();
  cJSON *fld = NULL, *fldd_0 = NULL, *fldd_1;

#if MUL
  for (int i = 0; i < 2; i++)
  {
    cJSON_AddItemToArray(root, fld = cJSON_CreateArray());

    cJSON_AddItemToArray(fld, fldd_0 = cJSON_CreateObject());
    cJSON_AddStringToObject(fldd_0, "Vertex Shader Path", sp[i].path.vertex_shader_path);
    cJSON_AddStringToObject(fldd_0, "Fragment Shader Path", sp[i].path.fragment_shader_path);

    cJSON_AddItemToArray(fld, fldd_1 = cJSON_CreateObject());
    cJSON_AddStringToObject(fldd_1, "Channel 0", sp[i].fsul.channel_0);
    cJSON_AddStringToObject(fldd_1, "Channel 1", sp[i].fsul.channel_1);
    cJSON_AddStringToObject(fldd_1, "Global Time", sp[i].fsul.global_time);
    cJSON_AddStringToObject(fldd_1, "Resolution", sp[i].fsul.resolution);
  }
#else

  cJSON_AddItemToArray(root, fld = cJSON_CreateArray());

  cJSON_AddItemToArray(fld, fldd_0 = cJSON_CreateObject());
  cJSON_AddStringToObject(fldd_0, "Vertex Shader Path", sp.path.vertex_shader_path);
  cJSON_AddStringToObject(fldd_0, "Fragment Shader Path", sp.path.fragment_shader_path);

  cJSON_AddItemToArray(fld, fldd_1 = cJSON_CreateObject());
  cJSON_AddStringToObject(fldd_1, "Channel 0", sp.fsul.channel_0);
  cJSON_AddStringToObject(fldd_1, "Channel 1", sp.fsul.channel_1);
  cJSON_AddStringToObject(fldd_1, "Global Time", sp.fsul.global_time);
  cJSON_AddStringToObject(fldd_1, "Resolution", sp.fsul.resolution);

#endif

  char *out = cJSON_Print(root);
  // 保存信息到文件
  writeToFile("result.txt", out);
  printf("Debug Info: %s", out);
  free(out);

  cJSON_Delete(root);
}

解析本地 txt 的函数：

void parseFile(char *filename)
{
    FILE *f;
    long len;
    char *data;

    f = fopen(filename, "rb");
    fseek(f, 0, SEEK_END);
    len = ftell(f);
    fseek(f, 0, SEEK_SET);
    data = (char *)malloc(len + 1);
    fread(data, 1, len, f);
    fclose(f);

    //easyParse(data);
    itemParse(data);

    free(data);
}

void itemParse(char *text)
{

    cJSON *json;

    json = cJSON_Parse(text);
    if (!json)
    {
        printf("Error before: [%s]\n", cJSON_GetErrorPtr());
    }
    else
    {
        int size_0 = cJSON_GetArraySize(json);
        printf("Shader Program Nums = %d\n", size_0);

        for (int i = 0; i < size_0; i++)
        {
            cJSON *pItem = cJSON_GetArrayItem(json, i);
            if (NULL == pItem)
            {
                continue;
            }
            int size_1 = cJSON_GetArraySize(pItem);
            //printf("Shader Program Item Nums = %d\n", size_1);
            printf("===========================\n");
            for (int j = 0; j < size_1; j++)
            {
                cJSON *ppItem = cJSON_GetArrayItem(pItem, j);

                //printJSON(ppItem);

                int size_2 = cJSON_GetArraySize(ppItem);
                printf("Shader Program Item Size  = %d\n", size_2);
                //printf("---------------------------\n");
                for (int k = 0; k < size_2; k++)
                {
                    cJSON *pppItem = cJSON_GetArrayItem(ppItem, k);

                    printJSON(pppItem);
                }
                printf("===========================\n");
            }
        }
    }

    cJSON_Delete(json);
}

生成的 txt 内容为：

开启 MUL 宏的情况

[
    [
        {
            "Vertex Shader Path": "../Shader/vs_0.glsl", 
            "Fragment Shader Path": "../Shader/fs_0.glsl"
        }, 
        {
            "Channel 0": "iChannel0", 
            "Channel 1": "iChannel1", 
            "Global Time": "iGlobalTime", 
            "Resolution": "iResolution"
        }
    ], 
    [
        {
            "Vertex Shader Path": "../Shader/vs_1.glsl", 
            "Fragment Shader Path": "../Shader/fs_1.glsl"
        }, 
        {
            "Channel 0": "iChannel0", 
            "Channel 1": "iChannel1", 
            "Global Time": "iGlobalTime", 
            "Resolution": "iResolution"
        }
    ]
]

或未开启 MUL 的情况

[
    [
        {
            "Vertex Shader Path": "../Shader/vs_0.glsl", 
            "Fragment Shader Path": "../Shader/fs_0.glsl"
        }, 
        {
            "Channel 0": "iChannel0", 
            "Channel 1": "iChannel1", 
            "Global Time": "iGlobalTime", 
            "Resolution": "iResolution"
        }
    ]
]

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