无法使用多重采样渲染到纹理

Question

我在此页面中运行了帧缓冲区示例-原始代码-（在 osx 10.8 中使用 glfw3 和 xcode 4.6 中的 glew），它工作正常，然后我想添加多重采样（以避免立方体边缘和地板上的锯齿状边缘，glfwWindowHint (GLFW_SAMPLES, 4)就足够了当直接渲染到后台缓冲区时），找到了一些指向 opengl.org 的答案，尝试使用glTexImage2DMultisample但它什么也没显示（黑屏）。帧缓冲区设置和渲染循环是：

// Create frame buffer
GLuint frameBuffer;
glGenFramebuffers(1, &frameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);

// Create texture to hold color buffer
GLuint texColorBuffer;
glGenTextures(1, &texColorBuffer);
glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, texColorBuffer);

//glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 4, GL_RGB, width, height, GL_FALSE);

/*
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
*/

//glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texColorBuffer, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D_MULTISAMPLE, texColorBuffer, 0);

// Create Renderbuffer Object to hold depth and stencil buffers
GLuint rboDepthStencil;
glGenRenderbuffers(1, &rboDepthStencil);
glBindRenderbuffer(GL_RENDERBUFFER, rboDepthStencil);
//glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, height);
glRenderbufferStorageMultisample (GL_RENDERBUFFER, 4, GL_DEPTH24_STENCIL8, width, height);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rboDepthStencil);

// ...

while (!window->shouldClose()) {
    static int rot = 0;

    // Bind our framebuffer and draw 3D scene (spinning cube)
    glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
    auto err_res = glCheckFramebufferStatus(GL_FRAMEBUFFER);
    if(err_res != GL_FRAMEBUFFER_COMPLETE) {
        ERR("Incomplete frameBuffer:%X!", err_res);
        goto end;
    }

    glBindVertexArray(vaoCube);
    glEnable(GL_DEPTH_TEST);
    glUseProgram(sceneShaderProgram);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texKitten);
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, texPuppy);

    // Clear the screen to white
    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


    glUniformMatrix4fv(uniModel, 1, GL_FALSE, glm::value_ptr(model));
    glUniformMatrix4fv(uniView, 1, GL_FALSE, glm::value_ptr(view));
    glUniformMatrix4fv(uniProj, 1, GL_FALSE, glm::value_ptr(proj));

    // Draw cube
    glEnable(GL_MULTISAMPLE);

    glDrawArrays(GL_TRIANGLES, 0, 36);

    glEnable(GL_STENCIL_TEST);

    // Draw floor
    glStencilFunc(GL_ALWAYS, 1, 0xFF);
    glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
    glStencilMask(0xFF);
    glDepthMask(GL_FALSE);
    glClear(GL_STENCIL_BUFFER_BIT);

    glDrawArrays(GL_TRIANGLES, 36, 6);

    // Draw cube reflection
    glStencilFunc(GL_EQUAL, 1, 0xFF);
    glStencilMask(0x00);
    glDepthMask(GL_TRUE);

    model = glm::scale(glm::translate(model, glm::vec3(0, 0, -1)), glm::vec3(1, 1, -1));
    glUniformMatrix4fv(uniModel, 1, GL_FALSE, glm::value_ptr(model));

    glUniform3f(uniColor, 0.3f, 0.3f, 0.3f);
    glDrawArrays(GL_TRIANGLES, 0, 36);
    glUniform3f(uniColor, 1.0f, 1.0f, 1.0f);

    glDisable(GL_STENCIL_TEST);                

    /*
    // Bind default framebuffer and draw contents of our framebuffer
    glBindFramebufferEXT(GL_FRAMEBUFFER, 0);
    glBindVertexArray(vaoQuad);
    glDisable(GL_DEPTH_TEST);
    glUseProgram(screenShaderProgram);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texColorBuffer);

    glDrawArrays(GL_TRIANGLES, 0, 6);
    */

    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);   // Make sure no FBO is set as the draw framebuffer
    glBindFramebuffer(GL_READ_FRAMEBUFFER, frameBuffer); // Make sure your multisampled FBO is the read framebuffer
    glDrawBuffer(GL_BACK);                       // Set the back buffer as the draw buffer
    glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GL_COLOR_BUFFER_BIT, GL_LINEAR);

    // Swap buffers
    glfwSwapBuffers(window->getHandle());
    glfwPollEvents();
}

• glVersion: 3.2 NVIDIA-8.10.44 304.10.65f03
• glRenderer：NVIDIA GeForce 9400M OpenGL 引擎

'EXT' 添加可能是不必要的，但我之前也尝试过在没有它们的情况下运行，结果是一样的。我究竟做错了什么？

编辑：现在绑定GL_TEXTURE_2D_MULTISAMPLE并GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE出现错误！

Answer 1

如果您检查了帧缓冲区对象的完整性，那么您现在可能已经发现了这一点……您的深度/模板缓冲区也需要进行多重采样。

如果一个附件的样本数与任何其他附件的样本数不同，则内核和 EXT FBO 扩展都将帧缓冲区视为多样本不完整。在您的情况下，您有一个带有4 个样本的颜色缓冲区附件和一个带有1 个样本的深度/模板附件。

姓名

glCheckFramebufferStatus — 检查帧缓冲区的完整性状态

描述

glCheckFramebufferStatus查询当前绑定到的帧缓冲区对象的完整性状态target。target必须是GL_DRAW_FRAMEBUFFER，GL_READ_FRAMEBUFFER或GL_FRAMEBUFFER。GL_FRAMEBUFFER相当于GL_DRAW_FRAMEBUFFER。

返回值是GL_FRAMEBUFFER_COMPLETE绑定到目标的帧缓冲区是否完整。否则，返回值确定如下：

[...]

GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE如果GL_RENDERBUFFER_SAMPLES所有附加的渲染缓冲区的值不同，则返回；如果GL_TEXTURE_SAMPLES所有附加纹理的值都不相同；或者，如果附加的图像是渲染缓冲区和纹理的混合，则 的值GL_RENDERBUFFER_SAMPLES与 的值不匹配GL_TEXTURE_SAMPLES。

要解决此问题，您需要分配一个包含 4 个样本的多重采样深度/模板附件：

glRenderbufferStorageMultisample (GL_RENDERBUFFER, 4, GL_DEPTH24_STENCIL8, width, height);

顺便说一句，由于您的实现是>= 3.0，因此您不需要任何东西的 EXT 后缀。EXT 扩展定义的所有常量都与 ARB/核心 FBO 相同，但某些 EXT 函数（例如glCheckFramebufferStatusEXT）具有更多限制性行为（例如，要求每个附件具有相同的图像尺寸）。