Cannot use certain variants with Mitsuba 3 Renderer - graphics

As the title suggests, I cannot use variants such as llvm, cuda and the auto-differentiable variants with mitsuba 3.
I have checked that they are indeed variants using mitsuba.variants() as well as making sure they are listed in the config file, but when I try to run in jupyter notebook, I get the error that the LLVM dll cannot be found. scalar_rgb and scalar_spectral both work fine.
I built mitsuba directly from the repository, and so it should have included all the necessary dlls.
and below shows the enabled variants in the config file.

Related

wxWidgets fails to build due to missing wxxml.lib

Apparently anything GUI-related in terms of components involves XML. I cannot go around actually configuring and building wxWidgets from source because of that. I'm new to wxWidgets.
My current setup is on Win10 with MSVC v141 (Visual Studio 2017) with the latest CMake version (currently 3.21).
Inside the config.cmake of the wxWidgets projects (using latest master branch) I see
wx_get_dependencies(EXTRALIBS_XML xml)
I am also calling CMake with -DwxUSE_XML=ON (among other parameters) but this still leads to:
the XML dependency is nowhere to be found
respectively it's not built
Linking then fails with the following error:
LINK : fatal error LNK1104: cannot open file 'wxxml.lib' [C:\Users\...\CMakeBuilds\ef5b5ada-ee42-7735-988a-ae37c735ccff\build\deps\build\wxwidgets\libs\qa\wxqa.vcxproj]
What library is actually wxWidgets using and how do I trigger it's retrieval and accordingly configuration and building? Since I am adding wxWidgets to my CMake project as an ExternalProject component, I would appreciated something in that line of thought. However any kind of information regarding this issue is more than welcome especially since it will shine light on how to configure other features (if I want them in the future) such as WebView.
The wxxml.lib issue is fixed now. While fixing it I also discovered a bug (of sort) in the build system of wxWidgets.
The reason why it failed to build this library in particular was actually quite simple but due to the lack of knowledge in the dependencies of wxWidgets. I thought that wxWidgets, given it depends on XML so much, has its own XML parser. Well, not really. The wxXML component actually uses and underlying 3rd party dependency called EXPAT, which - as you can see in my question - I have deactivated since it was giving me issues during the build (due to the still present problem of not being able to automatically retrieve dependencies).
What I did was to clone the libexpat repository, add it as an ExternalProject, set the variables for the libraries and include directory and pass them onto my wxWidgets project. But there is a catch...
The expat.cmake file looks as follows:
#############################################################################
# Name: build/cmake/lib/expat.cmake
# Purpose: Use external or internal expat lib
# Author: Tobias Taschner
# Created: 2016-09-21
# Copyright: (c) 2016 wxWidgets development team
# Licence: wxWindows licence
#############################################################################
if(wxUSE_EXPAT STREQUAL "builtin")
# TODO: implement building expat via its CMake file, using
# add_subdirectory or ExternalProject_Add
wx_add_builtin_library(wxexpat
src/expat/expat/lib/xmlparse.c
src/expat/expat/lib/xmlrole.c
src/expat/expat/lib/xmltok.c
)
set(EXPAT_LIBRARIES wxexpat)
set(EXPAT_INCLUDE_DIRS ${wxSOURCE_DIR}/src/expat/expat/lib)
elseif(wxUSE_EXPAT)
find_package(EXPAT REQUIRED)
endif()
I would use the *.cmake files of the 3rd party dependencies stored inside <ROOT_OF_WXWIDGETS_PROJECT>/build/cmake/lib to determine which variables I need to set if builtin is selected as the value for the respective library. Since I want to use my own I need sys (e.g. -DwxUSE_EXPAT=sys as a CMAKE_ARGS inside my wxWidgets ExternalProject) and also to pass the headers and libraries accordingly.
Given the file above one would assume that EXPAT_LIBRARIES is required. However after failing to build (yet again) and seeing that the reason was the activated expat build and that it was set as builtin I checked the log in detail and found the following error:
Could NOT find EXPAT (missing: EXPAT_LIBRARY) (found version "2.2.6")
Notice the EXPAT_LIBRARY. After passing it (-DEXPAT_LIBRARY=...) my build was complete. For me this is a bug or simply inconsistency between the dependency cmake file and the rest of the wxWidgets project.
It is important to note that I do not retrieve the external dependency through wxWidgets itself (see config.cmake and more precisely the macro wx_get_dependencies(...)). This solves the problem with a basic configuration and build of wxWidgets but if you don't want to tackle every dependency of wxWidgets on your own (why should you?), I recommend looking for a solution where the dependencies (at least the ones you don't want to deal with) are automatically retrieved, configured and build as builtin.

Vulkan.hpp compiling on one system but not another

I have the following generic function:
template <typename U>
auto CastVkArray(std::vector<U> &unique_handles)
{
std::vector<typename U::element_type> handles;
for(auto &u_handle : unique_handles) handles.push_back(*u_handle);
return handles;
}
The problem is/was that although I thought I instructed premake5 to use the version under a local directory in my project, it was using the system's installed version instead. The version mismatch meant that I was using an old vulkan.hpp header rather than the one I need.
Which I am temporarily using to convert unique handle arrays to non unique arrays. This code compiles just fine on my desktop (arch linux), however on my laptop (ubuntu) I get the error:
error: no type named ‘element_type’ in ‘class vk::UniqueHandle<vk::CommandBuffer>’
std::vector<typename U::element_type> handles;
I use premake 5 to generate my build environment and the script hasn't changed between the 2 systems. I checked that all the libraries I am using are the same version, in particualr, I made sure that the vulkan sdk is the same between the 2 computers.
I deleted and rebuilt my code multiple times to test for potential race conditions in compilation (just to see if anything changed), the error is always the same.
The one difference that I have found is that the reported version of premake in arch is 5.0.0-dev but on ubuntu it is 5.0.0-alpha14
But I have not been able to find the dev version on the official github repository of premake.

Modifying gethostbyname (res_search) source code - Linux Ubuntu 14.04 LTS

I am trying to modify the behaviour of the DNS lookup functions in Linux for my project by setting it to write a random string in a file as a test.
Linux use some DNS resolver functions, mainly gethostbyname. Looking forward, I found out that the resolver functions are within the glibc6 library. So, I downloaded it, compiled, generating the libresolv.so, libnss_dns.so dynamic libraries. Then, I replaced the existing ones on my system, at /usr/lib/x86_64-linux-gnu/.
Note: I found out these libraries are the ones that resolves queries by modifying gethostbyname code and compiling again. Then, I saw which dynamic libraries changed.
By creating a program that uses res_query directly (a resolver function) and compiling with -lresolv, it works (I used ldd command and it uses the resolver library I created). But, using gethostbyname directly from the code, using wget or browsing the web I can't get it right.
What am I doing wrong?
I discovered what should I do:
Firstly, the function called isn't gethostbyname. It is _nss_dns_gethostbyname3_r, defined in resolv/nss_dns/dns-host.c. Looking at the source I realized that this function called another one to resolve DNS names, __libc_res_nsearch, defined in resolv/res-query.c. So this is the function! I added some file writting commands there and it worked like a charm. I called it from C code using gethostbyname, used wget and Firefox, all worked. When you compile the code you should replace the libresolv.so of your system by the new one.
Note: my glibc version is 2.19.
I hope this helps someone.

How to link ".a" fat-static-libs with Apportable?

How do I link ".a" fat-static-libs with Apportable?
In the beginning, I did get a warning,
Warning: Library not found for lib-name. Try adding this to the
'deps' array in the 'add_params' section of your configuration.json
file. Check ~/.apportable/SDK/System for the directory names that
correspond to 'deps' entries.
I did add it to "deps" in the JSON right where it says this:
// A list of dependencies. Typically these correspond to frameworks in the xcode project.
My library isn't a framework, though. It's just a .a static library that has armv7, armv7s, and i386 parts which I assembled using lipo from two libraries (an armv7 and armv7s .a and a i386 .a) built with Xcode. They both use a single framework which is this Boost framework.
Adding it under deps squelched that warning message, but the apportable linker is still giving undefined references, so it is still not properly linking this file.
Now I know that Apportable has to re-jitter all this stuff, since Android won't know what to do with a Mac-executable format, so it's probably got to go pick apart my library and possibly turn it into an ELF-library before final linking. I'm not sure how to go about debugging this at this point, but is this supported at all?
Since you get "library not found" that means Apportable simply can't find the file. Hence the problem is merely with the file's location (or existence) and not what's in the library or how it is built.
The most common issue with dependent targets, especially Xcode projects dropped into other Xcode projects respectively workspaces with multiple projects, is that the resulting output of each target/project goes to different folders. Then Apportable (as well as xcodebuild under some circumstances) can't find the resulting libraries.
First step you should try is to make sure that the target dependencies are set. Select the app target, go to the Build Phases pane and under Target Dependencies add all frameworks and libraries that appear in the list and that your project depends on. This should ensure that the dependent frameworks/libraries do get built - because Xcode's built-in automatic dependency resolution isn't available to command line tools from what I understand. So you need to explicitly specify the dependent projects respectively their output.
If that doesn't help, you can force all targets to write their output to the same folder. Under Build Settings for every target change the Build Products Path (symbolic name: SYMROOT) to the same folder, for example ~/myprojectsbuildoutput
That way even dependent other projects will place their output in the same folder and xcodebuild as well as Apportable (it depends on xcodebuild) will be able to find the library files.
Tip: make sure your project builds successfully on the command line. Open Terminal, cd into the folder where the .xcodeproj bundle is and enter xcodebuild. If xcodebuild fails merely due to validation, disable Validate Built Product under Build Settings of the app target. If xcodebuild fails, Apportable likely isn't going to work either because it depends on xcodebuild. So as a prerequisite make sure that xcodebuild works on your project.
If xcodebuild also gives you "library not found" try calling it with a specific SYMROOT:
xcodebuild SYMROOT=~/myprojectsbuildoutput
If that then works you know you have to update each target's Build Projects Path. From what I know it's not currently possible (or not documented) to pass custom xcodebuild parameters via Apportable, so it needs to be set up in the .xcodeproj itself.

fatal error C1084: Cannot read type library file: 'Smegui.tlb': Error loading type library/DLL

I am trying to build an old version of an application which consists of VC++ projects that were written in Visual Studio 2003.
My OS is Windows 7 Enterprise (64-bit).
When I try and build the solution I get the following errors:
error C4772: #import referenced a type from a missing type library; '__missing_type__' used as a placeholder
fatal error C1084: Cannot read type library file: 'Smegui.tlb': Error loading type library/DLL.
They both complain about the following import statement:
#import "Smegui.tlb" no_implementation
This is not a case of the file path being incorrect as renaming the Smegui.tlb file causes the compiler to throw another error saying it cannot find the library.
Smegui is from another application that this one depends on. I thought perhaps I was missing a dll but there is no such thing as Smegui.dll.
All I know about .tlb files is that they are a type library and you can create them from an assembly using tlbexp.exe or regasm.exe (the later also registers the assembly with COM)
There is also an Apache Ant build script which uses a custom task to invoke devenv.com to build the projects. This is the same script that the build server originally used to build the application. It gives me the same errors when I try and run it.
The strangest thing about this is that I knew it ought to work seeing as it is all freshly checked out from subversion. I tried many different combinations of admin vs user elevation, VS vs Ant build, cleaning, release.
I have got it to build successfully about 5 times but the build seems to be non-deterministic.
If anyone can shed some light on how this tlb stuff even works or what this error might mean I would greatly appreciate it.
I found a far more reliable solution: open the tlb with oleview.exe and then close it.
Not sure what this actually does but it works every time.
I think oleview is actually one of the samples included with Visual Studio but I haven't had the time to debug it and see what it is doing.
I ran into this error because one type library was trying to load a dependent type library, which it could not find. Even though the dependent type library was in the same directory, and even though that directory was in the searchable path, the compiler would error loading the first type library, but not mention the dependent type library in the error.
To find the pseudo-missing type library, I ran Process Monitor (procman64.exe) during the compile. This showed that after the reported type library had successfully loaded, a dependent type library could not be found. It even showed all of the places that it was looking for the dependent type library, none of which were where it should have been looking (e.g.: ).
The fix was to add a <PreBuildEvent> to the project to copy the dependent .tlb file to one of the directories that was actually being searched.
<PreBuildEvent>
<Command>copy /Y ..\Lib\Interop\CWSpeechRecLib.tlb .\</Command>
</PreBuildEvent>
http://msdn.microsoft.com/en-us/library/sce74ah7%28VS.71%29.aspx
smegui.tlb is referencing some other tlb that the compiler can't find. If you have the .idl for smegui you might be able to figure out what the other is. I suspect the missing tlb is something that original build machine had registered but that your machine doesn't have registered.
A type library is a binary description of a set of interfaces, coclasses and enums. They're usually generated for COM components, in the case of tlbexp and regasm the tlb is created from the assembly metadata. For native COM components they are usually generated from an idl (Interface Description Language) file by the midl tool.
Edit:
I just noticed you're on x64 Windows. Are you building the project with a new version of Visual Studio? If so, are you targeting x86 or x64? If the latter, it may simply be a 32bit component that the compiler can't find (or less likely, a x64 component the x86 compiler can't find if you are targeting x86), for WOW64 the registry is virtualized for x86 vs. x64 applications.
Well I finally found out why I managed to get it to build sometimes and not others... sort of.
So long as I ran the build script with elevated administrator permissions and let that get as far as it could until that error occurred, then run the build script again as a protected administrator succeeded. Those steps must be done in that exact order with no other steps in between. If I try build in Visual Studio it does not work (although I did get it to succeed once). Probably some kind of virtualisation issue although it still doesn't quite make sense.
Well I don't need help on this any more and I know it's probably impossible to fully answer this question without knowing exactly what the build is doing. However if anyone does have any more thoughts I would happily receive them.
Cheers,
Steiny

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