From b83ca5e3ce99b79599d5e92c140536a51dc5d29d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Oskar=20Kwas=CC=81niewski?= <oskarkwasniewski@icloud.com>
Date: Wed, 26 Jun 2024 17:50:03 +0200
Subject: [PATCH] feat: add world tracking provider to render on acutal device

---
 include/bgfx/bgfx.h     |  2 ++
 include/bgfx/c99/bgfx.h |  5 +++++
 src/renderer_mtl.mm     | 28 ++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/include/bgfx/bgfx.h b/include/bgfx/bgfx.h
index 8b0f0ede7a..9aa782984f 100644
--- a/include/bgfx/bgfx.h
+++ b/include/bgfx/bgfx.h
@@ -645,6 +645,8 @@ namespace bgfx
 		                                   ///  create back-buffer color surface.
 		void* backBufferDS;                //!< Backbuffer depth/stencil. If `NULL`, bgfx will create a back-buffer
 		                                   ///  depth/stencil surface.
+		void *worldTracking;               //!< Native world tracking provider used for visionOS.
+		
 		NativeWindowHandleType::Enum type; //!< Handle type. Needed for platforms having more than one option.
 	};
 
diff --git a/include/bgfx/c99/bgfx.h b/include/bgfx/c99/bgfx.h
index 83354d46df..b4feae6d88 100644
--- a/include/bgfx/c99/bgfx.h
+++ b/include/bgfx/c99/bgfx.h
@@ -630,6 +630,11 @@ typedef struct bgfx_platform_data_s
      */
     void*                backBuffer;
     
+    /**
+     * Native world tracking provider used for visionOS.
+     */
+    void*             worldTracking;
+    
     /**
      * Backbuffer depth/stencil. If `NULL`, bgfx will create a back-buffer
      * depth/stencil surface.
diff --git a/src/renderer_mtl.mm b/src/renderer_mtl.mm
index 1fb46e3601..0eda3521df 100644
--- a/src/renderer_mtl.mm
+++ b/src/renderer_mtl.mm
@@ -531,6 +531,15 @@ bool init(const Init& _init)
 				, TextureFormat::Unknown
 				, TextureFormat::UnknownDepth
 				);
+		
+#if BX_PLATFORM_VISIONOS
+			if (g_platformData.worldTracking != NULL) {
+				m_worldTracking = (ar_world_tracking_provider_t)g_platformData.worldTracking;
+				m_deviceAnchor = ar_device_anchor_create();
+			} else {
+				BX_WARN(false, "Unable to setup world tracking, this prevents drawables from being presented on the device.");
+			}
+#endif
 			m_numWindows = 1;
 
 #if BX_PLATFORM_VISIONOS
@@ -1452,6 +1461,17 @@ bool isDeviceRemoved() override
 			return false;
 		}
 
+#if BX_PLATFORM_VISIONOS
+		void createPoseForTiming(cp_frame_timing_t timing, ar_world_tracking_provider_t world_tracking) {
+			cp_time_t presentationTime = cp_frame_timing_get_presentation_time(timing);
+			CFTimeInterval queryTime = cp_time_to_cf_time_interval(presentationTime);
+			ar_device_anchor_query_status_t status = ar_world_tracking_provider_query_device_anchor_at_timestamp(world_tracking, queryTime, m_deviceAnchor);
+			if (status != ar_device_anchor_query_status_success) {
+				BX_WARN(false, "Device anchor query failed.")
+			}
+		}
+#endif
+		
 		void flip() override
 		{
 			if (NULL == m_commandBuffer)
@@ -1470,6 +1490,10 @@ void flip() override
 					if (NULL != frameBuffer.m_swapChain->m_drawable)
 					{
 #if BX_PLATFORM_VISIONOS
+						
+						auto timingInfo = cp_drawable_get_frame_timing(frameBuffer.m_swapChain->m_drawable);
+						createPoseForTiming(timingInfo, m_worldTracking);
+						cp_drawable_set_device_anchor(frameBuffer.m_swapChain->m_drawable, m_deviceAnchor);
 						cp_drawable_encode_present(frameBuffer.m_swapChain->m_drawable, m_commandBuffer);
 						cp_frame_end_submission(frameBuffer.m_swapChain->m_frame);
 #else
@@ -2706,6 +2730,10 @@ void endEncoding()
 		Resolution m_resolution;
 		void* m_capture;
 		uint32_t m_captureSize;
+#if BX_PLATFORM_VISIONOS
+		ar_world_tracking_provider_t m_worldTracking;
+		ar_device_anchor_t m_deviceAnchor;
+#endif
 
 		// descriptors
 		RenderPipelineDescriptor m_renderPipelineDescriptor;