Mac OS X上的OpenGL纹理损坏

Question

I have a program that runs fine on both Windows and Linux on many different machines. It doesn't work correctly on any mac I've tried (few different machines with OS X 10.9 and 10.10). The program basically just renders a textured quad on the screen. The texture format is floating point.

It looks like this on Windows and Linux:

This is what it looks like on Mac:

So the texture data gets to the GPU but gets weirdly distorted. Texture wrap mode is set to clamp and you can see how it behaves from the picture.

Here's the minimal drawing code:

void Framebuffer::initialize()
{
    Settings& settings = App::getSettings();

    glGenTextures(1, &imageTextureId);
    glBindTexture(GL_TEXTURE_2D, imageTextureId);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    resampleProgramId = GLHelper::buildProgram(settings.framebuffer.resampleVertexShader, settings.framebuffer.resampleFragmentShader);

    resampleTextureUniformId = glGetUniformLocation(resampleProgramId, "texture0");
    resampleTextureWidthUniformId = glGetUniformLocation(resampleProgramId, "textureWidth");
    resampleTextureHeightUniformId = glGetUniformLocation(resampleProgramId, "textureHeight");
    resampleTexelWidthUniformId = glGetUniformLocation(resampleProgramId, "texelWidth");
    resampleTexelHeightUniformId = glGetUniformLocation(resampleProgramId, "texelHeight");

    const GLfloat vertexData[] = {
        -1.0f, -1.0f, 0.0f, 0.0f,
        1.0f, -1.0f, 1.0f, 0.0f,
        1.0f, 1.0f, 1.0f, 1.0f,
        -1.0f, -1.0f, 0.0f, 0.0f,
        1.0f, 1.0f, 1.0f, 1.0f,
        -1.0f, 1.0f, 0.0f, 1.0f,
    };

    glGenBuffers(1, &vertexBufferId);
    glBindBuffer(GL_ARRAY_BUFFER, vertexBufferId);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexData), vertexData, GL_STATIC_DRAW);

    glGenVertexArrays(1, &vaoId);
    glBindVertexArray(vaoId);
    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), 0);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (void*)(2 * sizeof(GLfloat)));
    glBindVertexArray(0);

    resize(settings.window.width, settings.window.height);
}

void Framebuffer::resize(int width, int height)
{
    image.resize(width, height);
    floatPixelData.resize(width * height * sizeof(float) * 4);

    // reserve the texture memory on the device
    glBindTexture(GL_TEXTURE_2D, imageTextureId);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, (GLsizei)width, (GLsizei)height, 0, GL_RGBA, GL_FLOAT, 0);
    glGenerateMipmap(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, 0);
}

void Framebuffer::render()
{
    int imageWidth = image.getWidth();
    int imageHeight = image.getHeight();

    glUseProgram(resampleProgramId);
    glUniform1i(resampleTextureUniformId, 0);

    std::vector<Color>& imagePixelData = image.getPixelData();

    // convert image data from Color to float array
    for (int i = 0; i < (int)imagePixelData.size(); ++i)
    {
        int pixelIndex = i * 4;

        floatPixelData[pixelIndex] = (float)imagePixelData[i].r;
        floatPixelData[pixelIndex + 1] = (float)imagePixelData[i].g;
        floatPixelData[pixelIndex + 2] = (float)imagePixelData[i].b;
        floatPixelData[pixelIndex + 3] = (float)imagePixelData[i].a;
    }

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, imageTextureId);
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, (GLsizei)imageWidth, (GLsizei)imageHeight, GL_RGBA, GL_FLOAT, &floatPixelData[0]);
    glGenerateMipmap(GL_TEXTURE_2D);

    glBindVertexArray(vaoId);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    glBindVertexArray(0);

    glBindTexture(GL_TEXTURE_2D, 0);
    glUseProgram(0);

    GLHelper::checkError("Could not render the framebuffer");
}

For the sake of testing all shaders were replaced with minimal color pass-through versions.

Here's what I've tried with no luck:

• different internal texture formats
• different combinations of calling glGenerateMipmap
• different vertex and texcoord values
• different texture clamp and min/max filter settings (mipmap on/off)
• different viewport values

The same code works fine on Windows and Linux.

What could cause such corruption only Mac?

Answer 1

I'm not sure if this is the only problem in your code (if the problem is in your code at all), but there is definitely a problem with your mipmap generation. You have this sequence of calls:

glBindTexture(GL_TEXTURE_2D, framebufferTextureId);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, (GLsizei)windowWidth, (GLsizei)windowHeight, 0, GL_RGBA, GL_FLOAT, 0);
glGenerateMipmap(GL_TEXTURE_2D);

glGenerateMipmap() is not a state setting call that specifies that you will want to have mipmaps generated once the texture is filled with data. What it does is generate mipmaps from the data in the texture at the time of the call . Since you just allocated the texture data in the previous call, and do not have data in the texture yet, glGenerateMipmap() will do nothing.

Later, you use this texture:

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

At this point, the texture does not have mipmaps, even though the sampling mode is set to use mipmaps.

What you need to do is generate mipmaps after the texture has been filled with data. You can remove the glGenerateMipmap() call from its current place in setWindowSize() , and for example move it just below the second coder fragment above:

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

glGenerateMipmap(GL_TEXTURE_2D);

Answer 2

Ok, I finally figured it out. The attribute locations inside the vertex shader were switched on Mac OS X. By just good luck it rendered something on the screen with texcoords as vertex positions and vice versa.

I could have used glBindAttribLocation to fix it, but I updated the shaders to version 330 and used the layout(location = 0) attribute. That worked fine too.