glGenerateMipmap(GL_TEXTURE_2D) Exception Trhown

Question

I am trying to put texture in my model, but when I try running my code I get the following error:
Exception thrown at 0x00007FFE262AE37C (ig9icd64.dll) in COMP371.exe: 0xC0000005: Access violation reading location 0x000001799C69D000.

Can someone please help me understand why I am getting this error?
Here is my code for my texture:

Texture::Texture(std::string texturePath)
{
    glGenTextures(1, &textureId);
    glBindTexture(GL_TEXTURE_2D, textureId);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    unsigned char* data = stbi_load(texturePath.c_str(), &width, &height, &depth, 0);
  
    if (data) {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D); // Here is where the error is thrown
    }
    else {
        std::cout << "Failed to load texture: " << texturePath << std::endl;
    }

    glBindTexture(GL_TEXTURE_2D, 0);
    stbi_image_free(data);
}

What are the values of widht, height and depth? And have you tried calling glPixelStorei(GL_UNPACK_ALIGNMENT, 1) before uploading the data? My guess is that with a (default) padding of four bytes, data contains less memory than OpenGL wants to read. — BDL

datenwolf datenwolf · Accepted Answer · 2021-08-11T13:15:47

It's not glGenerateMipmap that crashes, it's glTexImage2D. And that happens because you're passing it invalid data and/or invalid format specification. The layout of data must match the format and dimensions you pass to glTexImage2D. The depth value returned by stbi_load for example tells you, how many components (each having 8 bits) there are. You must select the appropriate OpenGL image format from that:

if( 0 == depth || 4 < depth ){ throw std::runtime_error("invalid depth"); }
GLenum const fmt[] = {GL_RED, GL_RG, GL_RGB, GL_RGBA};
glTexImage2D(
    GL_TEXTURE_2D, 0, fmt[depth-1],
    width, height, 0,
    fmt[depth-1], GL_UNSIGNED_BYTE, data);

glGenerateMipmap(GL_TEXTURE_2D) Exception Trhown

1 Answers