From 05d70ea99de89b75c6582f06073370d0bb3f5af1 Mon Sep 17 00:00:00 2001
From: Matthew Endsley <mendsley@gmail.com>
Date: Fri, 5 Jun 2015 02:00:26 -0700
Subject: [PATCH] VR: Fix skewed viewports with buffered eye textures

Bug fix for #419

Viewport calculations need to take VR eye buffer size into
account. Noticable at the older 100px boundary. Skewing still
exists at newer 8px buffer, but is harder to notice.
Eventually causes pretty bad eye strain, though.

Easily reproduced by setting the buffer to something obscenely
large, such as 2048.
---
 src/ovr.cpp            |  8 ++++++++
 src/ovr.h              |  1 +
 src/renderer_d3d11.cpp | 13 +++++++++++--
 src/renderer_gl.cpp    | 13 +++++++++++--
 4 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/ovr.cpp b/src/ovr.cpp
index 169e1004e..85792f40e 100644
--- a/src/ovr.cpp
+++ b/src/ovr.cpp
@@ -69,6 +69,14 @@ namespace bgfx
 		ovr_Shutdown();
 	}
 
+	void OVR::getViewport(uint8_t _eye, Rect* _viewport)
+	{
+		_viewport->m_width = (m_rtSize.w - s_eyeBuffer)/2;
+		_viewport->m_height = m_rtSize.h;
+		_viewport->m_x = _eye * (m_rtSize.w + s_eyeBuffer + 1)/2;
+		_viewport->m_y = 0;
+	}
+
 	bool OVR::postReset(void* _nwh, ovrRenderAPIConfig* _config, bool _debug)
 	{
 		if (_debug)
diff --git a/src/ovr.h b/src/ovr.h
index 58fd9ec31..dd7d6426a 100644
--- a/src/ovr.h
+++ b/src/ovr.h
@@ -67,6 +67,7 @@ namespace bgfx
 		void init();
 		void shutdown();
 
+		void getViewport(uint8_t _eye, Rect* _viewport);
 		bool postReset(void* _nwh, ovrRenderAPIConfig* _config, bool _debug = false);
 		void postReset(const ovrTexture& _texture);
 		void preReset();
diff --git a/src/renderer_d3d11.cpp b/src/renderer_d3d11.cpp
index fe8f33241..0205bd314 100644
--- a/src/renderer_d3d11.cpp
+++ b/src/renderer_d3d11.cpp
@@ -3844,8 +3844,17 @@ BX_PRAGMA_DIAGNOSTIC_POP();
 							PIX_BEGINEVENT(D3DCOLOR_RGBA(0xff, 0x00, 0x00, 0xff), viewNameW);
 						}
 
-						viewState.m_rect.m_x = eye * (viewState.m_rect.m_width+1)/2;
-						viewState.m_rect.m_width /= 2;
+#if BGFX_CONFIG_USE_OVR
+						if (m_ovr.isEnabled())
+						{
+							m_ovr.getViewport(eye, &viewState.m_rect);
+						}
+						else
+#endif // BGFX_CONFIG_USE_OVR
+						{
+							viewState.m_rect.m_x = eye * (viewState.m_rect.m_width+1)/2;
+							viewState.m_rect.m_width /= 2;
+						}
 					}
 					else
 					{
diff --git a/src/renderer_gl.cpp b/src/renderer_gl.cpp
index 772d6bd3a..6e28630cf 100644
--- a/src/renderer_gl.cpp
+++ b/src/renderer_gl.cpp
@@ -4955,8 +4955,17 @@ namespace bgfx { namespace gl
 							GL_CHECK(glInsertEventMarker(0, viewName) );
 						}
 
-						viewState.m_rect.m_x = eye * (viewState.m_rect.m_width+1)/2;
-						viewState.m_rect.m_width /= 2;
+#if BGFX_CONFIG_USE_OVR
+						if (m_ovr.isEnabled())
+						{
+							m_ovr.getViewport(eye, &viewState.m_rect);
+						}
+						else
+#endif // BGFX_CONFIG_USE_OVR
+						{
+							viewState.m_rect.m_x = eye * (viewState.m_rect.m_width+1)/2;
+							viewState.m_rect.m_width /= 2;
+						}
 					}
 					else
 					{