Method EmitDraw

engine/PoseidonGL33/EngineGL33_VertexBuffer.cpp:301–346

The emission seam — issues the indexed draw call from a typed `Poseidon::render::frame::Draw` value: bind the mesh VAO, rebind TEXTURE0/TEXTURE1, upload the per-draw world matrix, flush PS constants, issue glDrawElements with the index byte offset computed from `d.indexBegin`. Pass-level state (descriptor, shader, sampler) was bound by `ApplyPassState` before the `DrawSectionTL` call. Bails on a

// crash the GL driver — the I-22 runtime check fires the warning,
// this path just stays defensive.
void EngineGL33::EmitDraw(const Poseidon::render::frame::Draw& d)
{
    if (!_glContext)
        return;
    if (d.mesh.vao == 0 || d.indexCount <= 0)
        return;

    GL33Bind::Vao(d.mesh.vao);

    // TEXTURE0 + TEXTURE1 binds.  Both handles were captured from the
    // `SetTexture` / `SetMultiTexturing` callsites, so this rebinds
    // the same multi-tex configuration regardless of what's currently
    // bound.  Handle 0 is skipped (sentinel).  The TEXTURE1 bind ends
    // with the active unit back on TEXTURE0 — every subsequent call
    // assumes that.
    if (d.textures[1].id != 0)
        GL33Bind::Tex2D(1, d.textures[1].id);
    if (d.textures[0].id != 0)
        GL33Bind::Tex2D(0, d.textures[0].id);
    else
        GL33Bind::ActiveUnit(0);

    // Per-draw world-matrix upload from the typed `Draw.world` —
    // never inherited from whatever was last in `_currentDrawItem`.
    // `UploadVSWorldMatrix` flushes VS constants internally;
    // FlushPSConstants is explicit because PS-side state (material,
    // sampler, texture-color routing) is bound by the descriptor /
    // `ApplyPipeline` path.
    UploadVSWorldMatrix(reinterpret_cast<const float*>(&d.world));
    FlushPSConstants();

    const std::intptr_t offsetBytes = Poseidon::render::frame::ComputeIndexByteOffset(d.indexBegin, sizeof(VertexIndex));
    if (_instCount > 1)
    {
        // Instanced run: the WorldInstances UBO already holds the matrices;
        // the per-draw upload above wrote slot 0 (= matrices[0]) again,
        // which is harmless. gl_InstanceID selects the rest.
        glDrawElementsInstanced(GL_TRIANGLES, d.indexCount, GL_UNSIGNED_SHORT, reinterpret_cast<void*>(offsetBytes),
                                _instCount);
    }
    else
    {
        glDrawElements(GL_TRIANGLES, d.indexCount, GL_UNSIGNED_SHORT, reinterpret_cast<void*>(offsetBytes));
    }
    ++Poseidon::gPerfDrawCalls;
}

void EngineGL33::Clear(bool clearZ, bool clear, PackedColor color)
{