无法为Windows x86构建JAssimp.dll

Question

So, I'm trying to get into LWJGL, and part of this is loading 3D models, and I thought I'd use JAssimp for this. The readme specifies two steps, building a native component, and a .jar component. The jar was just an ant build, and so it happened without incident. The part that's difficult is the native library. I've been trying to link it, without success. I've included the assimp include directories, included Java's headers, and linked to JAssimp's assimp.lib. However, I still get these errors:

jassimp.obj : error LNK2019: unresolved external symbol _aiImportFile referenced in function _Java_jassimp_Jassimp_aiImportFile@20
jassimp.obj : error LNK2019: unresolved external symbol _aiReleaseImport referenced in function _Java_jassimp_Jassimp_aiImportFile@20
jassimp.obj : error LNK2019: unresolved external symbol _aiGetErrorString referenced in function _Java_jassimp_Jassimp_aiImportFile@20
C:\Users\Kevin\Downloads\assimp-3.1.1-win-binaries\port\jassimp\jassimp-native\src\Release\Jassimp.dll : fatal error LNK1120: 3 unresolved externals

Googling around leads to mostly the same question, but with no answers, and one guy on facepunch that apparently found a solution, but pulled an https://xkcd.com/979/ and never mentioned how. Obviously, I've missed linking to some library, but I'm not sure what else to link to, Assimp only provided me one, and I'm not sure what else I need. Am I installing it wrong?

Answer 1

For anyone else who stumbles across this with the same problem, the answer is to do it the old-fashioned way and compile the C++ Assimp yourself. This will give you, (among other things) a new assimp.lib. Link with this instead of the one provided, and the error will go away.

Answer 2

How To Build

I) buiid the primary shared object libassimp.so: issue these commands in AssImp/assimp-3.2 a. cmake CMakeLists.txt -G 'Unix Makefiles' b. make c. results in AssImp/assimp-3.2/lib

II) build the native library by issuing this command in jassimp-native/src: a. $ gcc jassimp.cpp -I/usr/lib/jvm/java-7-openjdk-amd64/include/ \\ -I/usr/lib/jvm/java-7-openjdk-amd64/include/linux \\ -I/$HOME/AssImp/assimp-3.2/include \\ -L/$HOME/AssImp/assimp-3.2/lib/libassimp.so -shared -fPIC -o libjassimp.so

libjassimp.so is required at runtime and must be located in java.library.path:
b. sudo cp /$HOME/AssImp/assimp-3.2/port/jassimp/jassimp-native/src/libjassimp.so   /usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/

III) Java binding The java library is built using ant. Executing "ant" in the port/jassimp directory should be sufficient to build the library including the docs. The java build is configured to create java 1.6 classes

The Jassimp.jar file generated by the "ant" call has to be incorporated
in your build.xml file:

<target name="init">
   <property name="imports"      value="${libs}/jogl-all.jar:${libs}/gluegen-rt.jar:${libs}/jassimp.jar" />

<target name="compile" depends="prepare">
   <compilerarg line="-Xlint -cp ${imports}" />

All of the above is the good news; I successfully built my code.

The bad news is that upon execution I received the following error: java: symbol lookup error: /usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/libjassimp.so: undefined symbol: aiImportFile