无法通过多重采样渲染到纹理 [英] Cannot render to texture with multisampling

问题描述

我在此页-

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

可能没有必要添加'EXT'，但是我也尝试了在没有它们的情况下运行，结果是相同的.我在做什么错了?

现在绑定GL_TEXTURE_2D_MULTISAMPLE并出现GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE错误！

解决方案

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抓住了这一点...您的深度/模板缓冲区也需要进行多重采样. /p>

如果一个附件的样本数量与其他附件不同，则核心和EXT FBO扩展均将帧缓冲区视为 多样本不完整 依恋.就您而言，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.

名称

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

说明

glCheckFramebufferStatus 查询当前绑定到 target 的帧缓冲区对象的完整性状态. target 必须为 GL_DRAW_FRAMEBUFFER ， GL_READ_FRAMEBUFFER 或 GL_FRAMEBUFFER . GL_FRAMEBUFFER 等同于 GL_DRAW_FRAMEBUFFER .

如果绑定到目标的帧缓冲区已完成，则返回值为 GL_FRAMEBUFFER_COMPLETE .否则，返回值确定如下:

[...]

如果所有附加的渲染缓冲区的 GL_RENDERBUFFER_SAMPLES 值都不相同，则返回

GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE ；否则，将返回

GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE .如果 GL_TEXTURE_SAMPLES 的值对于所有附加纹理都不相同；或者，如果附加的图像是渲染缓冲区和纹理的混合，则 GL_RENDERBUFFER_SAMPLES 的值与 GL_TEXTURE_SAMPLES 的值不匹配.

---

要解决此问题，您需要分配具有4个样本的多样本深度/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 ，因此您不需要任何后缀EXT. EXT扩展定义的所有常量都与ARB/核心FBO相同，但是某些EXT函数(例如glCheckFramebufferStatusEXT)具有更严格的行为(例如，要求每个附件具有相同的图像尺寸). /em>

I ran the framebuffers example in this page -original code- (using glfw3 and glew in xcode 4.6 in osx 10.8), it worked fine, then I wanted to add multisampling (to avoid jagged edges on cube edges and on the floor, glfwWindowHint (GLFW_SAMPLES, 4) was enough when rendering directly to the back-buffer), found some answers directing to opengl.org, tried to use glTexImage2DMultisample but it displayed nothing (black screen). The framebuffer settings and rendering loop is:

// 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 Engine

The 'EXT' additions are probably unnecessary but I also tried to run without them before and the result was the same. What am I doing wrong?

EDIT: Now binding GL_TEXTURE_2D_MULTISAMPLE and getting GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE error!

解决方案

If you checked your framebuffer object for completeness, you would probably have caught this by now... your depth/stencil buffer needs to be multisampled as well.

A framebuffer is considered multisample incomplete by both core and the EXT FBO extension if one attachment has a different number of samples than any other attachment. In your case, you have a color buffer attachment with 4 samples and a depth/stencil attachment with 1 sample.

Name

glCheckFramebufferStatus — check the completeness status of a framebuffer

Description

glCheckFramebufferStatus queries the completeness status of the framebuffer object currently bound to target. target must be GL_DRAW_FRAMEBUFFER, GL_READ_FRAMEBUFFER or GL_FRAMEBUFFER. GL_FRAMEBUFFER is equivalent to GL_DRAW_FRAMEBUFFER.

The return value is GL_FRAMEBUFFER_COMPLETE if the framebuffer bound to target is complete. Otherwise, the return value is determined as follows:

[...]

GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE is returned if the value of GL_RENDERBUFFER_SAMPLES is not the same for all attached renderbuffers; if the value of GL_TEXTURE_SAMPLES is the not same for all attached textures; or, if the attached images are a mix of renderbuffers and textures, the value of GL_RENDERBUFFER_SAMPLES does not match the value of GL_TEXTURE_SAMPLES.

---

To fix this, you need to allocate a multisampled depth/stencil attachment with 4 samples:

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

By the way, since your implementation is >= 3.0, you do not need the EXT suffix on anything. All of the constants defined by the EXT extension are identical to ARB / core FBOs, but some of the EXT functions (such as glCheckFramebufferStatusEXT) have more restrictive behavior (requiring each attachment to have the same image dimensions, for instance).

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