Hi,

I have C++ Vulkan based project using Qt framework. QVulkanInstance and QVulkanWindow does lot of things for me like validation etc. but I can't figure out due Vulkan low level API how to troubleshoot Vulkan errors. I am trying to render terrain using tessellation shaders. I am learning from SaschaWillems tutorial for tessellation rendering. I think I am setting some value for rendering pass wrong in MapTile.cpp but unable to find which cause I dont know how to troubleshoot it.

Whats the problem?

App freezes on second end draw call

Why?

QVulkanWindow: Device lost

Validation layers debug

qt.vulkan: Vulkan init (vulkan-1.dll)
qt.vulkan: Supported Vulkan instance layers: QVector(QVulkanLayer("VK_LAYER_NV_optimus" 1 1.1.84 "NVIDIA Optimus layer"), QVulkanLayer("VK_LAYER_RENDERDOC_Capture" 0 1.0.0 "Debugging capture layer for RenderDoc"), QVulkanLayer("VK_LAYER_VALVE_steam_overlay" 1 1.1.73 "Steam Overlay Layer"), QVulkanLayer("VK_LAYER_LUNARG_standard_validation" 1 1.0.82 "LunarG Standard Validation Layer"))
qt.vulkan: Supported Vulkan instance extensions: QVector(QVulkanExtension("VK_KHR_device_group_creation" 1), QVulkanExtension("VK_KHR_external_fence_capabilities" 1), QVulkanExtension("VK_KHR_external_memory_capabilities" 1), QVulkanExtension("VK_KHR_external_semaphore_capabilities" 1), QVulkanExtension("VK_KHR_get_physical_device_properties2" 1), QVulkanExtension("VK_KHR_get_surface_capabilities2" 1), QVulkanExtension("VK_KHR_surface" 25), QVulkanExtension("VK_KHR_win32_surface" 6), QVulkanExtension("VK_EXT_debug_report" 9), QVulkanExtension("VK_EXT_swapchain_colorspace" 3), QVulkanExtension("VK_NV_external_memory_capabilities" 1), QVulkanExtension("VK_EXT_debug_utils" 1))
qt.vulkan: Enabling Vulkan instance layers: ("VK_LAYER_LUNARG_standard_validation")
qt.vulkan: Enabling Vulkan instance extensions: ("VK_EXT_debug_report", "VK_KHR_surface", "VK_KHR_win32_surface")
qt.vulkan: QVulkanWindow init
qt.vulkan: 1 physical devices
qt.vulkan: Physical device [0]: name 'GeForce GT 650M' version 416.64.0
qt.vulkan: Using physical device [0]
qt.vulkan: queue family 0: flags=0xf count=16 supportsPresent=1
qt.vulkan: queue family 1: flags=0x4 count=1 supportsPresent=0
qt.vulkan: Using queue families: graphics = 0 present = 0
qt.vulkan: Supported device extensions: QVector(QVulkanExtension("VK_KHR_8bit_storage" 1), QVulkanExtension("VK_KHR_16bit_storage" 1), QVulkanExtension("VK_KHR_bind_memory2" 1), QVulkanExtension("VK_KHR_create_renderpass2" 1), QVulkanExtension("VK_KHR_dedicated_allocation" 3), QVulkanExtension("VK_KHR_descriptor_update_template" 1), QVulkanExtension("VK_KHR_device_group" 3), QVulkanExtension("VK_KHR_draw_indirect_count" 1), QVulkanExtension("VK_KHR_driver_properties" 1), QVulkanExtension("VK_KHR_external_fence" 1), QVulkanExtension("VK_KHR_external_fence_win32" 1), QVulkanExtension("VK_KHR_external_memory" 1), QVulkanExtension("VK_KHR_external_memory_win32" 1), QVulkanExtension("VK_KHR_external_semaphore" 1), QVulkanExtension("VK_KHR_external_semaphore_win32" 1), QVulkanExtension("VK_KHR_get_memory_requirements2" 1), QVulkanExtension("VK_KHR_image_format_list" 1), QVulkanExtension("VK_KHR_maintenance1" 2), QVulkanExtension("VK_KHR_maintenance2" 1), QVulkanExtension("VK_KHR_maintenance3" 1), QVulkanExtension("VK_KHR_multiview" 1), QVulkanExtension("VK_KHR_push_descriptor" 2), QVulkanExtension("VK_KHR_relaxed_block_layout" 1), QVulkanExtension("VK_KHR_sampler_mirror_clamp_to_edge" 1), QVulkanExtension("VK_KHR_sampler_ycbcr_conversion" 1), QVulkanExtension("VK_KHR_shader_draw_parameters" 1), QVulkanExtension("VK_KHR_storage_buffer_storage_class" 1), QVulkanExtension("VK_KHR_swapchain" 70), QVulkanExtension("VK_KHR_variable_pointers" 1), QVulkanExtension("VK_KHR_win32_keyed_mutex" 1), QVulkanExtension("VK_EXT_conditional_rendering" 1), QVulkanExtension("VK_EXT_depth_range_unrestricted" 1), QVulkanExtension("VK_EXT_descriptor_indexing" 2), QVulkanExtension("VK_EXT_discard_rectangles" 1), QVulkanExtension("VK_EXT_hdr_metadata" 1), QVulkanExtension("VK_EXT_inline_uniform_block" 1), QVulkanExtension("VK_EXT_shader_subgroup_ballot" 1), QVulkanExtension("VK_EXT_shader_subgroup_vote" 1), QVulkanExtension("VK_EXT_vertex_attribute_divisor" 3), QVulkanExtension("VK_NV_dedicated_allocation" 1), QVulkanExtension("VK_NV_device_diagnostic_checkpoints" 2), QVulkanExtension("VK_NV_external_memory" 1), QVulkanExtension("VK_NV_external_memory_win32" 1), QVulkanExtension("VK_NV_shader_subgroup_partitioned" 1), QVulkanExtension("VK_NV_win32_keyed_mutex" 1), QVulkanExtension("VK_NVX_device_generated_commands" 3), QVulkanExtension("VK_NVX_multiview_per_view_attributes" 1))
qt.vulkan: Enabling device extensions: QVector(VK_KHR_swapchain)
qt.vulkan: memtype 0: flags=0x0
qt.vulkan: memtype 1: flags=0x0
qt.vulkan: memtype 2: flags=0x0
qt.vulkan: memtype 3: flags=0x0
qt.vulkan: memtype 4: flags=0x0
qt.vulkan: memtype 5: flags=0x0
qt.vulkan: memtype 6: flags=0x0
qt.vulkan: memtype 7: flags=0x1
qt.vulkan: memtype 8: flags=0x1
qt.vulkan: memtype 9: flags=0x6
qt.vulkan: memtype 10: flags=0xe
qt.vulkan: Picked memtype 10 for host visible memory
qt.vulkan: Picked memtype 7 for device local memory
qt.vulkan: Color format: 44 Depth-stencil format: 129
qt.vulkan: Creating new swap chain of 2 buffers, size 600x370
qt.vulkan: Actual swap chain buffer count: 2 (supportsReadback=1)
qt.vulkan: Allocating 1027072 bytes for transient image (memtype 8)
qt.vulkan: Creating new swap chain of 2 buffers, size 600x368
qt.vulkan: Releasing swapchain
qt.vulkan: Actual swap chain buffer count: 2 (supportsReadback=1)
qt.vulkan: Allocating 1027072 bytes for transient image (memtype 8)
QVulkanWindow: Device lost
qt.vulkan: Releasing all resources due to device lost
qt.vulkan: Releasing swapchain

I am not so sure if this debug helps somehow :(( I dont want you to debug it for me. I just want to learn how I should debug it and find where problem is located. Could you give me guide please?

Source code

Source code rendering just few vertices (working)

Difference between links are:

• Moved from Qt math libraries to glm
• Moved from QImage to gli for Texture class
• Added tessellation shaders
• Disabled window sampling
• Rendering terrain using heightmap and texturearray (Added normals and UV)

Thanks

Ok so problem was in QVulkanWindow implementation of Qt framework. Because I was unable to activate debug callback I wrote my own implementation which works.