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我正在尝试将一个小场景渲染到一个立方体贴图中，以用于 WebGL 中的反射——使用 Emscripten（C++ 到 JavaScript）。我的代码只是通过 6 个面，并将所有对象渲染到立方体纹理的当前绑定侧。该代码适用于桌面版本，没有错误。但是 WebGL 说：

渲染警告：没有纹理绑定到单元 0。

在检查 glGetError(); 后，我也收到错误 1282；当我调用“glDrawElements”时。两条消息出现 30 次（将 5 个网格渲染为 6 个面 - 6*5=30）

Fbo & 纹理创建

    glGenFramebuffers(1, &m_FboId);
    glBindFramebuffer(GL_FRAMEBUFFER, m_FboId);

    glGenTextures(1, &m_glId);
    glBindTexture(GL_TEXTURE_CUBE_MAP, m_glId);

    for (unsigned int i = 0; i < 6; i++)
        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, CUBEMAP_SIZE, CUBEMAP_SIZE, 0, GL_RGB, GL_FLOAT, nullptr);

    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

#if !WEB
    glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE); // Wrap_R is invalid in WebGL
#endif

    glBindTexture(GL_TEXTURE_CUBE_MAP, 0);

    glGenRenderbuffers(1, &m_DepthId);
    glBindRenderbuffer(GL_RENDERBUFFER, m_DepthId);

    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, CUBEMAP_SIZE, CUBEMAP_SIZE);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_DepthId);

    m_DrawBuffers[0] = GL_COLOR_ATTACHMENT0;
    glDrawBuffers(1, m_DrawBuffers);

    int fbo_Status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
    if (fbo_Status != GL_FRAMEBUFFER_COMPLETE) printf(" ::ENGINE:: FBO Creation Failed! glError: %i\n", fbo_Status);

    glBindRenderbuffer(GL_RENDERBUFFER, 0);
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

渲染：

    glBindFramebuffer(GL_FRAMEBUFFER, m_FboId);
    glViewport(0, 0, CUBEMAP_SIZE, CUBEMAP_SIZE);

    Object* objectPtr;

    shader.bind();
    shader.loadProjectionMtx(math::perspective(90.0f, 1.0f, 0.001f, 300.0f)[0][0]);
    shader.loadCameraPosition(m_Position.x, m_Position.y, m_Position.z);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    math::mat4 viewMtx(1.0f);

    for (unsigned int f = 0; f < 6; f++)
    {
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + f, m_glId, 0);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        if (f == 2)
            viewMtx = math::lookAt(m_Position, m_Position - math::vec3( 0.0f, -1.0f,  0.0f), math::vec3(0.0f, 0.0f, 1.0f));
        else if (f == 1)
            viewMtx = math::lookAt(m_Position, m_Position - math::vec3( 1.0f,  0.0f,  0.0f), math::vec3(0.0f, -1.0f, 0.0f));
        else if (f == 4)
            viewMtx = math::lookAt(m_Position, m_Position - math::vec3( 0.0f,  0.0f, -1.0f), math::vec3(0.0f, -1.0f, 0.0f));
        else if (f == 3)
            viewMtx = math::lookAt(m_Position, m_Position - math::vec3( 0.0f,  1.0f,  0.0f), math::vec3(0.0f, 0.0f, -1.0f));
        else if (f == 0)
            viewMtx = math::lookAt(m_Position, m_Position - math::vec3(-1.0f,  0.0f,  0.0f), math::vec3(0.0f, -1.0f, 0.0f));
        else if (f == 5)
            viewMtx = math::lookAt(m_Position, m_Position - math::vec3( 0.0f,  0.0f,  1.0f), math::vec3(0.0f, -1.0f, 0.0f));

        shader.loadViewMtx(viewMtx[0][0]);

        for (unsigned int i = 0; i < m_Entities.size(); i++)
        {
            shader.loadModelMtx(m_Entities[i]->getMtx()[0][0]);

            objectPtr = static_cast<Object*>(m_Entities[i]);

            for (int t = 0; t < 3; t++)
            {
                glActiveTexture(GL_TEXTURE0 + t);
                glBindTexture(GL_TEXTURE_2D, objectPtr->getTextureId(t));
                glUniform1i(objectPtr->getUniformLoc(t), t);
            }

            glBindVertexArray(objectPtr->getMesh()->getVao());
            int error = glGetError();
            glDrawElements(GL_TRIANGLES, objectPtr->getMesh()->getNumberOfIndices(), GL_UNSIGNED_SHORT, 0);
            error = glGetError(); if (error != 0) printf("GL ERROR: %i\n", error);
            glBindVertexArray(0);
        }
    }

    glBindFramebuffer(GL_FRAMEBUFFER, 0);

我在这里做了什么 WebGL 不喜欢的事情？当我将场景渲染到 2D 纹理到另一个 FBO 时，这正是我渲染场景的方式。唯一不同的是，这一次，我渲染成立方体纹理。

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