My application is not finding the OpenCascade DLLs , even though they are in the path

My application is not finding the OpenCascade DLLs , even though they are in the path.

I have built my own simple application  OCSimple.exe, that uses OpenCascade, version 7.0.0.

It's going pretty well. I'm on Windows 10, developing using Visual Studio 2015. 

I have to work in 32bit, as a customer requirement. I've successfully built 32 bit versions of the OpenCascade DLLs.

My application calls the DLLs, all is well - EXCEPT for one thing. It only works if the OpenCascade DLLs (TKernel.dll​ , etc) are in the SAME directory as my application OCSimple.exe.

I want to be able to have the OpenCascade DLLs  in a different directory from the EXE, and put this directory​ in the path.

I want to distribute just the necessary OpenCascade  DLLs , shaders and any other resources necessary  with my application and AVOID having the USERS do a full install of OpenCascade.​

I am setting the path  and environment variables for OpenCascade in a batch file which then calls my  OCSimple.exe, in the same way the samples do it.

I  believe  I am setting the path correctly, as I CAN put the third party DLLS (FreeImage.dll etc) in their own directory and they are found.

Is there some environment variable I need to set to point to the OpenCascade DLLs?

For instance, I am setting the location of the shaders, with:

     set "CSF_ShadersDirectory=C:\Test\OCSimple_and_Delphi\Shaders"​

I have tried setting CASROOT to the location of the OpenCascade DLLS:

    set "CASROOT=C:\Test\OCSimple_and_Delphi\OpenCascade DLLs"

But this does not help.


To summarise the program setup is:


     Contains the exe OCSimple.exe

     Works if OpenCascade DLLs are here

     Contains batch file run_OCSimple.bat , to set up environment variables and path, and call OCSimple.exe See below for its contents.


     Contains the simple shaders used

C:\Test\OCSimple_and_Delphi\Third Party DLLs

     Contains the third party DLLs , e.g FreeImage.dll. These are found!

C:\Test\OCSimple_and_Delphi\OpenCascade DLLs

    Contains the OpenCascade DLLs,   (TKernel.dll​ , etc). These are not found.


The contents of  run_OCSimple.bat

     Setlocal EnableDelayedExpansion

​     set "CASROOT=C:\Test\OCSimple_and_Delphi\OpenCascade DLLs"

     set "CSF_ShadersDirectory=C:\Test\OCSimple_and_Delphi\Shaders"

     SET PATH=%PATH%;C:\Test\OCSimple_and_Delphi\OpenCascade DLLs
     SET PATH=%PATH%;C:\Test\OCSimple_and_Delphi\Third Party DLLs


     call OCSimple.exe


This site: mentions setting CSF_GraphicShr to point to TKOpenGl.dll , but I believe this is for an older version of OpenCascade, I don't see any reference to it in version 7.0.0.

Any help appreciated,



Jim Williams's picture

OK,I have a solution, but it does seem to be  different from what the Opencascade documentation suggests.

It works if  I set the the path to the Opencascade DLLs with the WinAPI call

SetDllDirectory(), .

E.g  SetDllDirectory("C:\\MyProject\\OpenCascadeDLLS")

But as I said, it doesn't work if I add "C:\\MyProject\\OpenCascadeDLLS" to the PATH environment variable, as it says I should here:

​Anyone have any idea why this is?



Jim Williams's picture


There was an older version of the OpenCascade DLLS elsewhere on my PC, used/installed by another app.

These were in the system  DLL directory , so were getting picked up before the ones in the path.

Hence the need to use SetDllDirectory() to specify the location of the ones I need to use.