Question

I am trying to load a texture into my small OpenGL app. I've seen a lot of recommendations for the stb library. It really fits my needs as it doesn't have to be built or linked, I can just include the header.

Unfortunately, I can't seem to get it to load a texture properly (on my Linux laptop or my Windows desktop). It finds the file correctly (because the dimensions properly fit whichever texture I am testing at the time) but it doesn't load the pixels correctly.

I first thought this was an error I was making with my OpenGL code, but upon further inspection of the array stb is returning to me, I have found that it is filled with 255 as every single value no matter what image I attempt to load.

Here is my texture loading code:

bool Texture::LoadTextureFromFile(std::string path)
{
  bool success = true;

  int comp, width, height;
  unsigned char* image = stbi_load(path.c_str(), &width,
      &height, &comp, 0);

  texture_width = width;
  texture_height = height;

  glGenTextures(1, &texture_id);

  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB,
      GL_UNSIGNED_BYTE, image);

  glBindTexture(GL_TEXTURE_2D, 0);

  stbi_image_free(image);

  return success;
}

I have been banging my head against this for a week now, and would really love some enlightenment on the issue.

I can also present my OpenGL initialization code if anyone thinks that would help.

Answer 1

你的opengl代码确实有错误。您必须在glGenTextures(1, &texture_id)之后绑定纹理。我通过添加代码来工作（我还将RGB更改为RGBA，因为我使用的图像文件是RGBA格式）。

bool load(std::string filename) {
  int w, h, comp; 
  GLuint t; 

  unsigned char * im = stbi_load(filename.c_str(), &w, &h, &comp, 0);

  glGenTextures(1, &t); 

  glBindTexture(GL_TEXTURE_2D, t);

  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, im); 

  glBindTexture(GL_TEXTURE_2D, 0);

  return true;
}

此代码适用于我。如果你说stbi_load只有255个值，你可能还有其他错误。确保您具有文件名的正确路径，并确保启用了纹理。

stb image loading library returning white textures

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