[vulkan] example-07-callback does not work well with a tiling wm.

[mcourteaux]

Describe the bug
This issue seems related to frame buffers not following nicely the window size.

Starting in Vulkan (with Debug) crashes with:

../../../src/renderer_vk.cpp (683): BGFX ---E-          RenderPass, Validation, 0: Validation Error: [ VUID-VkRenderPassBeginInfo-pNext-02852 ] Object 0: handle = 0xd10d270000000018, type = VK_OBJECT_TYPE_RENDER_PASS; Object 1: handle = 0x27d60e0000000019, type = VK_OBJECT_TYPE_FRAMEBUFFER; | MessageID = 0xdb2c5767 | vkCmdBeginRenderPass(): pRenderPassBegin->renderArea offset.x (0) + extent.width (1280) is greater than framebuffer width (621). The Vulkan spec states: If the pNext chain does not contain VkDeviceGroupRenderPassBeginInfo or its deviceRenderAreaCount member is equal to 0, renderArea.offset.x + renderArea.extent.width must be less than or equal to VkFramebufferCreateInfo::width the framebuffer was created with (https://vulkan.lunarg.com/doc/view/1.3.280.0/linux/1.3-extensions/vkspec.html#VUID-VkRenderPassBeginInfo-pNext-02852)
../../../src/renderer_vk.cpp (683): BGFX ---E-          RenderPass, Validation, 0: Validation Error: [ VUID-VkRenderPassBeginInfo-pNext-02852 ] Object 0: handle = 0xd10d270000000018, type = VK_OBJECT_TYPE_RENDER_PASS; Object 1: handle = 0x27d60e0000000019, type = VK_OBJECT_TYPE_FRAMEBUFFER; | MessageID = 0xdb2c5767 | vkCmdBeginRenderPass(): pRenderPassBegin->renderArea offset.x (0) + extent.width (1280) is greater than framebuffer width (621). The Vulkan spec states: If the pNext chain does not contain VkDeviceGroupRenderPassBeginInfo or its deviceRenderAreaCount member is equal to 0, renderArea.offset.x + renderArea.extent.width must be less than or equal to VkFramebufferCreateInfo::width the framebuffer was created with (https://vulkan.lunarg.com/doc/view/1.3.280.0/linux/1.3-extensions/vkspec.html#VUID-VkRenderPassBeginInfo-pNext-02852)
vkObject(0): ALLOC 0x14e0e4b0 of 424 byte(s)
vkObject(0): ALLOC 0x14e0fe20 of 2552 byte(s)
../../../src/bgfx.cpp(57): ALLOC 0x14e0fdf0 of 32 byte(s)
../../../src/renderer_vk.cpp(3766): ALLOC 0x14e20d20 of 15166 byte(s)
../../../src/renderer_vk.cpp(583): FREE 0x14e0e4b0
../../../src/renderer_vk.cpp(3778): FREE 0x14e20d20
vkCommand(0): ALLOC 0x14d52250 of 24 byte(s)
../../../src/renderer_vk.cpp(583): FREE 0x14d52250
../../../src/renderer_vk.cpp(7969): ASSERT VK_SUCCESS == vkresult -> vkWaitForFences(device, 1, &m_completedFence, 1U, (18446744073709551615UL)); VK error 0xfffffffc: VK_ERROR_DEVICE_LOST
Fatal error: 0x00000000: vkWaitForFences(device, 1, &m_completedFence, 1U, (18446744073709551615UL)); VK error 0xfffffffc: VK_ERROR_DEVICE_LOSTzsh: IOT instruction (core dumped)  ../../.build/linux64_gcc/bin/example-07-callbackDebug

Notice that the validation mechanism is complaining about unmatched resolutions.
Starting in OpenGL works for a bit, but you can see that the resolution is wrong:

After about 5, the resolution adjusts and I see (note that the updated resolution happened together with the printing of the line I marked in the yellow rectangle):

Afterwards quitting the example app crashes it with segfault:

---

Looking at the code, it seems that this 5 seconds is not random:

bgfx/examples/07-callback/callback.cpp

Lines 391 to 419 in 530a558

	bool update() override
	{
	bool exit = false;
	// 5 second 60Hz video
	if (m_frame < 300)
	{
	++m_frame;
	}
	else
	{
	m_reset &= ~BGFX_RESET_CAPTURE;
	exit = entry::processEvents(m_width, m_height, m_debug, m_reset, &m_mouseState);
	imguiBeginFrame(m_mouseState.m_mx
	, m_mouseState.m_my
	, (m_mouseState.m_buttons[entry::MouseButton::Left ] ? IMGUI_MBUT_LEFT : 0)
	| (m_mouseState.m_buttons[entry::MouseButton::Right ] ? IMGUI_MBUT_RIGHT : 0)
	| (m_mouseState.m_buttons[entry::MouseButton::Middle] ? IMGUI_MBUT_MIDDLE : 0)
	, m_mouseState.m_mz
	, uint16_t(m_width)
	, uint16_t(m_height)
	);
	showExampleDialog(this);
	imguiEndFrame();
	}

I believe the problem to be originating from the fact that the app is not processing events, and therefore not seeing the correct frame size yet. I suspect most people never see this issue, as the app probably gets initialized with the correct resolution and then does 5 seconds of not listening to events, but as I'm using a tiling window manager, the app doesn't get to choose it's resolution at startup. Vulkan says:

pRenderPassBegin->renderArea offset.x (0) + extent.width (1280) is greater than framebuffer width (621). The Vulkan spec states: If the pNext chain does not contain VkDeviceGroupRenderPassBeginInfo or its deviceRenderAreaCount member is equal to 0, renderArea.offset.x + renderArea.extent.width must be less than or equal to VkFramebufferCreateInfo::width the framebuffer was created with (https://vulkan.lunarg.com/doc/view/1.3.280.0/linux/1.3-extensions/vkspec.html#VUID-VkRenderPassBeginInfo-pNext-02852)

You can tell that OpenGL just ignores the window size and just does its thing regarding the first 5 seconds. Vulkan crashes badly with a device lost error.

Looking at the recording with OpenGL, I see:

So, it's like the backbuffer actually has the full resolution, but is just not rendered too completely.