Combining Vertex, Texture, and Normal Indices in an OBJ Parser

It sounds like you’re on the right track by wanting to avoid multiple EBOs! The idea of combining vertex, texture, and normal indices into a single structure can definitely help streamline your rendering process.

You could consider creating a single vertex structure that holds all the necessary data for each vertex. For instance, you might set up a structure like this:

    struct Vertex {
        glm::vec3 position;   // Vertex position
        glm::vec2 texCoord;   // Texture coordinate
        glm::vec3 normal;     // Vertex normal
    };
    

After defining your vertex structure, you’ll want to create a single array of vertices instead of separate arrays for positions, texture coordinates, and normals.

When you parse the OBJ file, you’ll read the vertex, texture, and normal indices and then build your vertex array accordingly. Instead of having separate index buffers for vertex positions, texture coordinates, and normals, you can do something like this:

    std::vector vertices;
    for (const auto& face : faces) {
        for (const auto& index : face.indices) {
            Vertex vertex;
            vertex.position = positions[index.vertexIndex];
            vertex.texCoord = texCoords[index.textureIndex];
            vertex.normal = normals[index.normalIndex];
            vertices.push_back(vertex);
        }
    }
    

This way, you can create a single VBO (Vertex Buffer Object) from your vertex array and a single EBO that uses the vertex indices. When binding your vertex data with a VAO (Vertex Array Object), just make sure to set the attributes correctly:

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, position));
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, texCoord));
    glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, normal));
    

In this way, you are effectively mapping each vertex to its attributes in one unified structure, making it easier to work with and potentially more efficient for rendering.

Ultimately, this combination approach can simplify the management of your meshes while ensuring that you can still use texture and normal mapping effectively. Good luck with your OBJ parser!