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Hi all, I have been looking for a while for a solution to this problem but I cannot find it. The code base I am working on currently is nearly identical to the code base here: https://github.com/vurtun/nuklear/tree/ ... _opengles2.

What I would like to do is within the same instance of the program fully initialize and delete an SDL+GLES instance twice within the run time of the same program. I have adapted the code base posted above to simply call the contents of main() twice with a slight pause in between. However on the second run the following assert fails:
This can be found on line 116 in the file nuklear_sdl_gles2.h. I used the following code to print the error:
maxLength is zero after glGetShaderiv returns. Also if I manually set maxLength to a larger number glGetShaderInfoLog doesn't even touch infoLog. It leaves it completely empty. Any help would be greatly appreciated

My equivalent code is below. Only difference I can see is that I pass "NULL" for the length pointer when calling glGetShaderInfoLog
I get error text like this from it ..
The lines "e=0x0" are from code like this that I include after every gl call for use while developing to catch errors. When it works I disable them,
and finally remove them.
Are you sure there have not been any other errors before this code is executed ?
When did your code last check for errors by calling glGetError() ?

HTH
PeterO

PeterO wrote: ↑

Wed Aug 14, 2019 7:54 am

My equivalent code is below. Only difference I can see is that I pass "NULL" for the length pointer when calling glGetShaderInfoLog

Code: Select all

    glCompileShader(shaderId);

    glGetShaderiv(shaderId,GL_COMPILE_STATUS,&compiledOk );

    if(compiledOk == GL_FALSE)
    {
        GLint logLength;

        glGetShaderiv(shaderId,GL_INFO_LOG_LENGTH,&logLength);
      
        if(logLength > 1)
        {
            char *logText;
            logText = malloc((size_t)logLength);

            glGetShaderInfoLog(shaderId,logLength,NULL,logText);
            fprintf(stderr,"Shader from %s didn't compile!\n%s\n",filename,logText);            
         
            free(logText);
      }

      glDeleteShader(shaderId);
      return 0;
    }
    return(shaderId);
}

I get error text like this from it ..

Code: Select all

shader from WGbuttonVShader.c didn't compile!
0:2(1): preprocessor error: #version must appear on the first line

Vertex Shader (WGbuttonVShader.c) id=0
e=0x0
Fragment Shader (WGbuttonFShader.c) id=2
e=0x0
Program (WGProg) id=3
Linking WGProg failed: error: program lacks a vertex shader

The lines "e=0x0" are from code like this that I include after every gl call for use while developing to catch errors. When it works I disable them,
and finally remove them.

Code: Select all

#if ERRORCHEKING
        e = glGetError();
        printf("e=0x%x\n",e);
#endif

Are you sure there have not been any other errors before this code is executed ?
When did your code last check for errors by calling glGetError() ?

HTH
PeterO

I have your code pasted verbatim and glGetShaderiv returns 0. I have no idea how the status could be set to failed but gles decides to give no output. How is that possible?

What is in the vertex and fragment shader files you are compiling ?

Are you sure there is any source code on the second run ? It's not getting deleted after the first time is it ?

PeterO

PeterO wrote: ↑

Wed Aug 14, 2019 7:01 pm

What is in the vertex and fragment shader files you are compiling ?

Are you sure there is any source code on the second run ? It's not getting deleted after the first time is it ?

PeterO

Here is the exact source code I am using: https://github.com/vurtun/nuklear/blob/ ... dl_gles2.h.

It doesn't seem like I delete the shader files... seems to be defined in line actually. Take a look at the function nk_sdl_device_create() for exactly what I do.

PeterO wrote: ↑

Wed Aug 14, 2019 7:01 pm

What is in the vertex and fragment shader files you are compiling ?

Are you sure there is any source code on the second run ? It's not getting deleted after the first time is it ?

PeterO

Okay minor update. I tried outputting glGetString(GL_VERSION) and I noticed on the second run that it outputted (NULL). Which means I didn't even have a valid gl context to begin with on the second run, that's why there was no output from glGetShaderInfoLog. I traced it back to the following issue: SDL_CreateWindow() returns NULL the second time I call the function. The error is as follows: "Could not initialize OpenGL / GLES library". This is probably an issue with how I clean up SDL so I'll create a new issue in the appropriate place.

Ok, that makes sense. You could perhaps add some more checks on return values etc. then you'll catch these sorts of problems earlier on. As I said before I find frequent calls to glGetError() while still developing code can save a lot of time trying to hunt down a failed call that only shows up later in the execution flow.

PeterO