网上很多家都有自己的拓展,比如pico家
Khronos给出的官方拓展接口说明:OpenXR™ Documentation and Extensions: Procedures and Conventions
拓展的实现需要以下几步:
目录
1:在runtime中新增接口
1.1 定义拓展,以及拓展接口的声明
openxr.h文件中进行函数的声明
#define XR_EXT_audio 1
#define XR_EXT_audio_SPEC_VERSION 1
#define XR_EXT_AUDIO_EXTENSION_NAME "XR_EXT_audio"#ifndef XR_NO_PROTOTYPES#ifdef XR_EXTENSION_PROTOTYPES
XRAPI_ATTR XrResult XRAPI_CALL
xrDistanceAttention(bool enable, float max, float min, int radius);
#endif /* XR_EXTENSION_PROTOTYPES */
#endif /* !XR_NO_PROTOTYPES */
1.2 函数指针的定义
函数指针必须以PFN_开头,这个是openxr规范之一
#define XR_EXT_audio 1
#define XR_EXT_audio_SPEC_VERSION 1
#define XR_EXT_AUDIO_EXTENSION_NAME "XR_EXT_audio"
typedef XrResult (XRAPI_PTR *PFN_xrDistanceAttention)(bool enable, uint32_t max, uint32_t min, uint32_t radius);#ifndef XR_NO_PROTOTYPES
#ifdef XR_EXTENSION_PROTOTYPES
XRAPI_ATTR XrResult XRAPI_CALL
xrDistanceAttention(bool enable, float max, float min, int radius);
#endif /* XR_EXTENSION_PROTOTYPES */
#endif /* !XR_NO_PROTOTYPES */
1.3 函数指针的赋值
oxr_api_funcs.h中oxr_xrGetInstanceProcAddr函数中在Instance实例化后,会调用handle_non_null,这时对函数进行赋值,即会对1.1中的函数前加个oxr_
static XrResult
handle_non_null(struct oxr_instance *inst, struct oxr_logger *log, const char *name, PFN_xrVoidFunction *out_function)
{...
ENTRY(xrDistanceAttention);
...
}
ENTRY函数如下:
#define ENTRY(funcName) \
do { \
if (strcmp(name, #funcName) == 0) { \
PFN_##funcName ret = &oxr_##funcName; \
*out_function = (PFN_xrVoidFunction)(ret); \
return XR_SUCCESS; \
} \
} while (false)
1.4 oxr_函数的具体实现
XRAPI_ATTR XrResult XRAPI_CALL
oxr_xrDistanceAttention(bool enable, uint32_t max, uint32_t min, uint32_t radius) {
__android_log_print(ANDROID_LOG_DEBUG, "shanshan","shanshan add oxr_xrDistanceAttention");
}
2. sdk中如何调用拓展接口?
2.1 注册拓展
xr.xml中新增拓展
<!-- commands for XR_EXT_audio -->
<command successcodes="XR_SUCCESS" errorcodes="XR_ERROR_FUNCTION_UNSUPPORTED,XR_ERROR_VALIDATION_FAILURE">
<proto><type>XrResult</type> <name>xrDistanceAttention</name></proto>---拓展函数返回值+函数名
<param><type>XrBool32</type> <name>enable</name></param>--拓展函数入参1
<param><type>uint32_t</type> <name>max</name></param>--拓展函数入参2
<param><type>uint32_t</type> <name>min</name></param>--拓展函数入参3
<param><type>uint32_t</type> <name>radius</name></param>--拓展函数入参4
</command>--- supported="openxr"代表启动拓展,supported="disabled"代表禁用拓展,number号要注意一下,不能和别的相同
<extension name="XR_EXT_audio" number="498" type="instance" supported="openxr">------拓展名在runtime中的openxr.h中定义好了,#define XR_EXT_audio 1
<require>
<enum value="1" name="XR_EXT_audio_SPEC_VERSION"/>---在runtime中的openxr.h中定义好了,#define XR_EXT_audio_SPEC_VERSION 1
<enum value=""XR_EXT_audio"" name="XR_EXT_AUDIO_EXTENSION_NAME"/>---runtime中openxr.h定义好了,#define XR_EXT_AUDIO_EXTENSION_NAME "XR_EXT_audio"<command name="xrDistanceAttention"/>---拓展函数名,如果有多个,此处就有多行command
</require>
</extension>
2.2 调用拓展接口
void InitializeSystem() override {
...
PFN_xrDistanceAttention pfnXrDistanceAttention = nullptr;-----PFN_xrDistanceAttention 这个定义会在编译出来的openxr.h文件中能看到,与runtime中的openxr.h一致
__android_log_print(ANDROID_LOG_DEBUG, "shanshan", "SDK begin pfnXrDistanceAttention");
xrGetInstanceProcAddr(m_instance, "xrDistanceAttention",reinterpret_cast<PFN_xrVoidFunction*>(&pfnXrDistanceAttention));---拓展通过xrGetInstanceProcAddr调用
pfnXrDistanceAttention(true, 1, 1, 1);---调用runtime中的接口
__android_log_print(ANDROID_LOG_DEBUG, "shanshan", "SDK end pfnXrDistanceAttention");...
}
3. 接口调试
分别安装runtime应用,system broker应用,以及helloxr应用,然后启动system broker应用,选择monado runtime, 然后启动helloxr应用,由于,我们是在应用初始化的时候调用了接口,所以在helloxr应用启动后,会自动调用我们的拓展接口,log输出如下:
07-29 08:57:34.975 9289 9310 D shanshan: SDK begin pfnXrDistanceAttention----sdk中的log,调用开始
07-29 08:57:34.975 9289 9310 D shanshan: shanshan add oxr_xrDistanceAttention------这个是runtime中的log
07-29 08:57:34.975 9289 9310 D shanshan: SDK end pfnXrDistanceAttention----sdk中的log,调用结束