Method Init

engine/PoseidonGL33/EngineGL33_VertexBuffer.cpp:111–207

}

bool VertexBufferGL33::Init(const Shape& src, VBType type)
{
    if (src.NVertex() <= 0)
    {
        LOG_DEBUG(Graphics, "GL33: Empty vertices.");
        return false;
    }

    _dynamic = (type == VBDynamic || type == VBSmallDiscardable);
    _vertexCount = src.NVertex();

    // Core profile requires a non-zero VAO bound before any
    // GL_ELEMENT_ARRAY_BUFFER bind (the IBO binding is part of VAO state).
    // Create + bind the VAO first, then bind buffers inside it.
    glGenVertexArrays(1, &_vao);
    GL33Bind::Vao(_vao);

    // Create and fill VBO
    GLenum vbUsage = _dynamic ? GL_DYNAMIC_DRAW : GL_STATIC_DRAW;
    glGenBuffers(1, &_vbo);
    glBindBuffer(GL_ARRAY_BUFFER, _vbo);
    glBufferData(GL_ARRAY_BUFFER, _vertexCount * sizeof(SVertex), nullptr, vbUsage);
    CopyVertices(src);

    // Count total indices (fan triangulation: N-gon → N-2 triangles)
    int indices = 0;
    for (Offset o = src.BeginFaces(); o < src.EndFaces(); src.NextFace(o))
    {
        const Poly& poly = src.Face(o);
        PoseidonAssert(poly.N() >= 3);
        indices += (poly.N() - 2) * 3;
    }
    _indexCount = indices;

    if (indices > 0)
    {
        // IBO bind goes into the VAO state we just bound above.
        glGenBuffers(1, &_ibo);
        Poseidon::render::ibo::BindOnActiveVao(_ibo);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices * sizeof(VertexIndex), nullptr, GL_STATIC_DRAW);
        // IBO is GL_STATIC_DRAW — `MapStaticWriteOnce` is the only
        // legal map helper for it.  Using `MapDynamicWriteInvalidate`
        // here would re-introduce B-028; the helper API doesn't expose
        // that combination.
        VertexIndex* iData = static_cast<VertexIndex*>(Poseidon::render::buf::MapStaticWriteOnce(GL_ELEMENT_ARRAY_BUFFER));
        if (!iData)
        {
            LOG_ERROR(Graphics, "GL33: IBO map failed");
            return false;
        }

        for (Offset o = src.BeginFaces(); o < src.EndFaces(); src.NextFace(o))
        {
            const Poly& poly = src.Face(o);
            for (int i = 2; i < poly.N(); i++)
            {
                *iData++ = poly.GetVertex(0);
                *iData++ = poly.GetVertex(i - 1);