Fixes texture format for NanoVG framebuffer. (#1147)

* Fixes pixel format for iOS.

* Fixes texture format of nanovg framebuffer.

examples/common/nanovg/nanovg_bgfx.cpp

@@ -1191,11 +1191,15 @@ NVGLUframebuffer* nvgluCreateFramebuffer(NVGcontext* ctx, int width, int height,
 NVGLUframebuffer* nvgluCreateFramebuffer(NVGcontext* _ctx, int _width, int _height, int _imageFlags)
 {
 	BX_UNUSED(_imageFlags);
+	bgfx::TextureHandle textures[] =
+	{
+		bgfx::createTexture2D(_width, _height, false, 1, bgfx::TextureFormat::RGBA8, BGFX_TEXTURE_RT),
+		bgfx::createTexture2D(_width, _height, false, 1, bgfx::TextureFormat::D24S8, BGFX_TEXTURE_RT | BGFX_TEXTURE_RT_WRITE_ONLY)
+	};
 	bgfx::FrameBufferHandle fbh = bgfx::createFrameBuffer(
-		  _width
-		, _height
-		, bgfx::TextureFormat::RGBA8
-		, BGFX_TEXTURE_NONE
+		  BX_COUNTOF(textures)
+		, textures
+		, true
 		);
 
 	if (!bgfx::isValid(fbh) )

src/renderer_mtl.mm

@@ -581,7 +581,7 @@ namespace bgfx { namespace mtl
 
 			if (BX_ENABLED(BX_PLATFORM_IOS) )
 			{
-				s_textureFormat[TextureFormat::D24S8].m_fmt = MTLPixelFormatDepth32Float;
+				s_textureFormat[TextureFormat::D24S8].m_fmt = MTLPixelFormatDepth32Float_Stencil8;
 
 				g_caps.formats[TextureFormat::BC1 ] =
 				g_caps.formats[TextureFormat::BC2 ] =