从纹理采样得到黑色 model 使用 opengl 和 SOIL2

Question

I'm trying to texture a model but all I get is the model rendered totally in black. i use SOIL2 library to load the image into the memory and the following code shows Load function in my Texture class.

bool Texture::Load(std::string texturePath) 
{
    int channels = 0; 
    
    unsigned char* image = SOIL_load_image(texturePath.c_str(), &mWidth, &mHeight, &channels, SOIL_LOAD_AUTO); 
    
    if (image == nullptr) 
    {
        std::cout << "Failed to load image " << texturePath; 
        return false; 
    }

    int format = GL_RGB;
    if (channels == 4) 
    {
        format = GL_RGBA; 
    }


    glGenTextures(1, &mTextureID); 
    glBindTexture(GL_TEXTURE_2D, mTextureID);


    glGenerateMipmap(GL_TEXTURE_2D); 
    glTextureParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTextureParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

    glTexImage2D(GL_TEXTURE_2D, 0, format, mWidth, mHeight, 0, format, GL_UNSIGNED_BYTE, image); 

    // Free data
    SOIL_free_image_data(image);
    
    return true; 
}

When I tried to debug the code I found out that the image pointer is pointing to an empty array as the following image I don't know if this is the problem or not but I found it weird and I'm pretty sure that the image is loaded successfully because mWidth and mHeight have their correct values.

My vertex shader :

#version 330 core

layout(location=0) in vec3 position ;
layout(location=1) in vec2 UVCoord ;
layout(location=2) in vec3 normal ;

uniform mat4 uWorldTransform ; 
uniform mat4 uView ; 
uniform mat4 uProjection ; 

out vec2 textCoord ; 

void main()
{
    gl_Position = uProjection * uView * uWorldTransform * vec4(position, 1.0) ; 
    textCoord = UVCoord ; 
}

and my fragment shader

#version 330 core

in vec2 textCoord ;

out vec4 color ;

uniform sampler2D myTexture ; 

void main()
{
    color = texture(myTexture , textCoord) ; 
}

My rendering code :

void Renderer::Draw() 
{
    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glEnable(GL_DEPTH_TEST); 
    std::vector<Actor*> actors = mGame->GetActors(); 
    for (auto act : actors) 
    {
        if (act->GetDrawable()) 
        {
            glm::mat4 worldTransform = act->GetWorldTransform();
            Shader* shader = mShaders[act->GetMesh()->GetShaderName()]; 
            VertexArrayObject* vao = act->GetMesh()->GetVAO();
            Texture* text = act->GetTexture(); 

            shader->Bind();
            shader->SetMatrix4Uniform("uWorldTransform", worldTransform);
            shader->SetMatrix4Uniform("uView", mView);
            shader->SetMatrix4Uniform("uProjection", mProjection);

            if (text) 
            {
                text->Bind(); 
            }

            vao->Bind();
            glDrawElements(GL_TRIANGLES, vao->GetEBOsize(), GL_UNSIGNED_INT, nullptr);
        }
    }

    glfwSwapBuffers(mGame->GetWindow());
}

This is the result I get on my screen:

Answer 1

Call glGenerateMipmap() after image upload ( glTexImage2D() ), otherwise it won't do anything useful since there isn't any image data in the texture yet to generate mipmaps from.

Or disable mip sampling by setting GL_TEXTURE_MIN_FILTER to GL_LINEAR / GL_NEAREST .

Also, be careful with GL_RGB & the default GL_UNPACK_ALIGNMENT of 4 . 1 is what you usually want.