From fa1897bd1f76e2bb9373400992679e7e3312430f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=91=D1=80=D0=B0=D0=BD=D0=B8=D0=BC=D0=B8=D1=80=20=D0=9A?=
 =?UTF-8?q?=D0=B0=D1=80=D0=B0=D1=9F=D0=B8=D1=9B?=
 <branimirkaradzic@gmail.com>
Date: Fri, 23 Jun 2023 19:16:32 -0700
Subject: [PATCH] Added headless validation for bgfx::init and bgfx::reset.

---
 src/bgfx.cpp          | 38 ++++++++++++++++++++++++--------------
 src/bgfx_p.h          |  9 +++++++++
 src/glcontext_egl.cpp |  4 ++--
 src/renderer_gl.cpp   | 28 ++++++++++++----------------
 4 files changed, 47 insertions(+), 32 deletions(-)

diff --git a/src/bgfx.cpp b/src/bgfx.cpp
index 0a7972a1b..3443fb045 100644
--- a/src/bgfx.cpp
+++ b/src/bgfx.cpp
@@ -1889,27 +1889,37 @@ namespace bgfx
 
 	bool Context::init(const Init& _init)
 	{
-		BX_ASSERT(!m_rendererInitialized, "Already initialized?");
+		if (m_rendererInitialized)
+		{
+			BX_TRACE("Already initialized!");
+			return false;
+		}
+
+		m_headless = true
+			&&  RendererType::Noop != _init.type
+			&&  NULL == _init.platformData.ndt
+			&&  NULL == _init.platformData.nwh
+			&&  NULL == _init.platformData.context
+			&&  NULL == _init.platformData.backBuffer
+			&&  NULL == _init.platformData.backBufferDS
+			;
+		BX_WARN(!m_headless, "bgfx platform data like window handle or backbuffer is not set, creating headless device.");
+
+		if (m_headless
+		&&  0 != _init.resolution.width
+		&&  0 != _init.resolution.height)
+		{
+			BX_TRACE("Initializing headless mode, resolution of non-existing backbuffer can't be larger than 0x0!");
+			return false;
+		}
 
 		m_init = _init;
 		m_init.resolution.reset &= ~BGFX_RESET_INTERNAL_FORCE;
 		m_init.resolution.numBackBuffers  = bx::clamp<uint8_t>(_init.resolution.numBackBuffers, 2, BGFX_CONFIG_MAX_BACK_BUFFERS);
-		m_init.resolution.maxFrameLatency = bx::min<uint8_t>(_init.resolution.maxFrameLatency, BGFX_CONFIG_MAX_FRAME_LATENCY);
+		m_init.resolution.maxFrameLatency =   bx::min<uint8_t>(_init.resolution.maxFrameLatency,   BGFX_CONFIG_MAX_FRAME_LATENCY);
 		m_init.resolution.debugTextScale  = bx::clamp<uint8_t>(_init.resolution.debugTextScale, 1, BGFX_CONFIG_DEBUG_TEXT_MAX_SCALE);
 		dump(m_init.resolution);
 
-		if (true
-		&&  RendererType::Noop != m_init.type
-		&&  NULL == m_init.platformData.ndt
-		&&  NULL == m_init.platformData.nwh
-		&&  NULL == m_init.platformData.context
-		&&  NULL == m_init.platformData.backBuffer
-		&&  NULL == m_init.platformData.backBufferDS
-		   )
-		{
-			BX_TRACE("bgfx platform data like window handle or backbuffer is not set, creating headless device.");
-		}
-
 		bx::memCopy(&g_platformData, &m_init.platformData, sizeof(PlatformData) );
 
 		m_exit    = false;
diff --git a/src/bgfx_p.h b/src/bgfx_p.h
index 509312841..a6ae7ed09 100644
--- a/src/bgfx_p.h
+++ b/src/bgfx_p.h
@@ -3130,6 +3130,7 @@ namespace bgfx
 			, m_rtMemoryUsed(0)
 			, m_textureMemoryUsed(0)
 			, m_renderCtx(NULL)
+			, m_headless(false)
 			, m_rendererInitialized(false)
 			, m_exit(false)
 			, m_flipAfterRender(false)
@@ -3168,6 +3169,13 @@ namespace bgfx
 		{
 			BGFX_MUTEX_SCOPE(m_resourceApiLock);
 
+			BX_ASSERT(false
+				|| !m_headless
+				|| 0 == _width
+				|| 0 == _height
+				, "Running in headless mode, resolution of non-existing backbuffer can't be larger than 0x0!"
+				);
+
 			const TextureFormat::Enum format = TextureFormat::Count != _format ? _format : m_init.resolution.format;
 
 			if (!g_platformDataChangedSinceReset
@@ -5363,6 +5371,7 @@ namespace bgfx
 
 		RendererContextI* m_renderCtx;
 
+		bool m_headless;
 		bool m_rendererInitialized;
 		bool m_exit;
 		bool m_flipAfterRender;
diff --git a/src/glcontext_egl.cpp b/src/glcontext_egl.cpp
index 8e109aa78..b8f24873e 100644
--- a/src/glcontext_egl.cpp
+++ b/src/glcontext_egl.cpp
@@ -300,8 +300,8 @@ EGL_IMPORT
 			{
 				EGLint pbAttribs[] =
 				{
-					EGL_WIDTH,  EGLint(_width),
-					EGL_HEIGHT, EGLint(_height),
+					EGL_WIDTH,  EGLint(1),
+					EGL_HEIGHT, EGLint(1),
 
 					EGL_NONE
 				};
diff --git a/src/renderer_gl.cpp b/src/renderer_gl.cpp
index 020dceba6..c8ad44c33 100644
--- a/src/renderer_gl.cpp
+++ b/src/renderer_gl.cpp
@@ -4138,29 +4138,25 @@ namespace bgfx { namespace gl
 
 		void setRenderContextSize(uint32_t _width, uint32_t _height, uint32_t _flags = 0)
 		{
-			if (_width  != 0
-			||  _height != 0)
+			if (!m_glctx.isValid() )
 			{
-				if (!m_glctx.isValid() )
-				{
-					m_glctx.create(_width, _height, _flags);
+				m_glctx.create(_width, _height, _flags);
 
 #if BX_PLATFORM_IOS
-					// iOS: need to figure out how to deal with FBO created by context.
-					m_backBufferFbo = m_msaaBackBufferFbo = m_glctx.getFbo();
+				// iOS: need to figure out how to deal with FBO created by context.
+				m_backBufferFbo = m_msaaBackBufferFbo = m_glctx.getFbo();
 #endif // BX_PLATFORM_IOS
-				}
-				else
-				{
-					destroyMsaaFbo();
+			}
+			else
+			{
+				destroyMsaaFbo();
 
-					m_glctx.resize(_width, _height, _flags);
+				m_glctx.resize(_width, _height, _flags);
 
-					uint32_t msaa = (_flags&BGFX_RESET_MSAA_MASK)>>BGFX_RESET_MSAA_SHIFT;
-					msaa = bx::uint32_min(m_maxMsaa, msaa == 0 ? 0 : 1<<msaa);
+				uint32_t msaa = (_flags&BGFX_RESET_MSAA_MASK)>>BGFX_RESET_MSAA_SHIFT;
+				msaa = bx::uint32_min(m_maxMsaa, msaa == 0 ? 0 : 1<<msaa);
 
-					createMsaaFbo(_width, _height, msaa);
-				}
+				createMsaaFbo(_width, _height, msaa);
 			}
 
 			m_flip = true;