6 Replies Latest reply on Oct 12, 2017 9:52 AM by Ronald_Intel

    Bug in Intel Vulkan driver

    thom36

      It is currently impossible to use a reverse-z technique with your Vulkan driver as it completely ignores minDepth and maxDepth fields in VkViewport structure.

       

      The driver always defaults to minDepth = 0.0f and maxDepth = 1.0f, even if both fields are set to minDepth = 1.0f and maxDepth = 0.0f, producing wrong depth buffering results.

       

      This technique is mentioned in one of your tutorials:

      API without Secrets: Introduction to Vulkan* Part 3: First Triangle | Intel® Software

       

      More info on Khronos pages:

      https://www.khronos.org/registry/vulkan/specs/1.0/man/html/VkViewport.html

       

      Drivers affected:

      -15.45 and 15.46 on Windows 7 x64 / Windows 10 x64

       

      Hardware used:

      -Intel HD 530 (Intel Core i7 6700k)

       

      NVIDIA / AMD hardware works as expected, only Intel is affected.

       

      SSU scan attached.

        • 1. Re: Bug in Intel Vulkan driver
          Ronald_Intel

          Hello thom36,

           

          Thank you for reporting this issue to us. If it is not asking too much, can you add the issue details using the table format as detailed here: Default level information for reporting Graphics issues

          Once we have this info I'll report it directly to our development team.

           

          Kindest Regards,

          Ronald M.

          • 2. Re: Bug in Intel Vulkan driver
            thom36

            Thank You, Ronald.

             

             

            Category

            Questions

            Answers (N/A if not applicable)

            Description

            Provide a detailed description of the issue

            Intel's Vulkan driver ignores minDepth and maxDepth fields in VkViewport structure, always defaults to minDepth=0.0f and maxDepth=1.0f disallowing to use a reverse-z technique

            Please place an X to the right of the option showing how often you see this issue using specific steps. (Ex: 'Every few times a game is started it flickers.' <- This would be "Often")

            Always (100%): X

            Often (51-99%):

            Sporadic (20-50%):

            Very Sporadic (<20%):

            Hardware (HW)

            Brand and Model of the system.

            Custom built desktop PC

            Hybrid or switchable graphics system?
            ie Does it have AMD or NV graphics too?

            PC also has GeForce GTX 960 in PCI Express slot, monitor cable connected to Intel HD 530 (i7 6700k)

            Make and model of any Displays that are used to see the issue (see note2 below).
            LFP
            = Local Flat Panel (Laptop panel)
            EFP = External Flat Panel (Monitor you plug in)

            Tested on 3 monitors:

            ASUS MX239H EFP

            SAMSUNG 743BM EFP

            SAMSUNG 797MB EFP

            but the issue can be observed on any display

            How much memory [RAM] in the system (see note2 below).

            16GB

            Provide any other hardware needed to replicate the issue.
            ie: Cables&brand, cable type [vga, hdmi, DP, etc], dock, dongles/adapters, etc

            N/A

            Hardware Stepping (see note1 below).

            PCI\VEN_8086&DEV_1912&SUBSYS_86941043&REV_06

            PCI\VEN_8086&DEV_1912&SUBSYS_86941043

            PCI\VEN_8086&DEV_1912&CC_030000

            PCI\VEN_8086&DEV_1912&CC_0300

            Software (SW)

            Operating System version (see note2 below).

            Windows 10 AU x64 and Windows 7 x64

            VBIOS (video BIOS) version. This can be found in “information page” of CUI (right click on Desktop and select “Graphics Properties”.

            1046.0

            Graphics Driver version; for both integrated Intel and 3rd party vendors (see note2 below).

            Intel: 21.20.16.4678 (15.45, tested on Windows 7 x64) and 22.20.16.4729 (15.46, tested on Windows 10 AU x64)

            NVIDIA: 384.94 on Windows 7 x64, 382.05 on Windows 10 AU x64

            SW or Apps version used to replicate the issue.

            Vulkan SDK 1.0.51, custom built app

            Configurations

            Single display, clone, or extended (see note2 below).

            Single display

            Display resolution & refresh rate setting of each display (see note2 below).

            ASUS MX239H: 1920x1080@60

            SAMSUNG 743BM: 1280x1024@60

            SAMSUNG 797MB: 1024x768@100

            AC or DC mode, i.e. is power cable plugged in or not?

            AC mode

            How to repro

            Please provide steps to replicate the issue.  These steps are very crucial to finding the root cause and fix.
            A screenshot to illustrate the issue is a huge plus. A video of the failure is even better! Attach to the post or provide the YouTube link.

            1. set minDepth=1.0f and maxDepth=0.0f in VkViewport
            2. clear depth buffer to 0.0f or render a triangle with depth=0.0f
            3. notice depth buffer isn't calculated in reverse

            ...

            • 3. Re: Bug in Intel Vulkan driver
              Ronald_Intel

              Hello thom36,

               

              I apologize for not replying sooner, I try to stay away from the "we're working on it" kind of updates.

              With the information you provided, I filed internal bug ID 1406462374, and our devs were able to reproduce the issue.

              Today I was informed that we have a fix checked-in, so please look forward to our next 15.46 and higher driver releases.

               

              Thank you for taking the time to report this issue to us.

               

              Kindest Reegards,

              Ronald M.

              1 of 1 people found this helpful
              • 4. Re: Bug in Intel Vulkan driver
                thom36

                That's an excellent news, thank you for doing a fantastic job.

                 

                I will be waiting for the next driver update.

                • 5. Re: Bug in Intel Vulkan driver
                  thom36

                  I installed the latest update that has been released yesterday (15.47.02.4815 (22.20.16.4815)) but I see no changes whatsoever.

                   

                  Could you please check if the fix has been included in the mentioned update?

                   

                  With viewport.minDepth=1.0f and viewport.maxDepth=0.0f, depth that should be written for a triangle with depth=0.95f is 0.05f, not 0.95f.

                   

                  I use VK_FORMAT_D32_SFLOAT_S8_UINT format.

                  • 6. Re: Bug in Intel Vulkan driver
                    Ronald_Intel

                    Hi again thom36,

                     

                    Thank you for your reply. Let me check with our devs, I think the fix was checked-in after this particular driver package was finalized, but need to confirm it first to be sure.

                    I'll let you know once I have more details.

                     

                    Best Regards,

                    Ronald M.