在OpenGL 4.x中创建和读取一维纹理

Question

我在OpenGL 4.x中使用一维纹理有问题。

我以这种方式创建了我的一维纹理(BTW:我删除了错误检查以使代码更清晰、更短-通常是在每次调用BLUE_ASSERTEx(glGetError() == GL_NO_ERROR, "glGetError failed.");之后)：

glGenTextures(1, &textureId_);

// bind texture
glBindTexture(GL_TEXTURE_1D, textureId_);

// tells OpenGL how the data that is going to be uploaded is aligned
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

BLUE_ASSERTEx(description.data, "Invalid data provided");

    glTexImage1D(
        GL_TEXTURE_1D,      // Specifies the target texture. Must be GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.
        0,                  // Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
        GL_RGBA32F,
        description.width,  
        0,                  // border: This value must be 0.
        GL_RGBA, 
        GL_FLOAT,
        description.data);
    BLUE_ASSERTEx(glGetError() == GL_NO_ERROR, "glGetError failed.");

// texture sampling/filtering operation.
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri (GL_TEXTURE_1D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri (GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri (GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

glBindTexture(GL_TEXTURE_1D, 0);

创建之后，我尝试以这样的方式读取创建的纹理的像素数据: const宽度= width_；const高度= 1；

// Allocate memory for depth buffer screenshot
float* pixels = new float[width*height*sizeof(buw::vector4f)];

// bind texture
glBindTexture(GL_TEXTURE_1D, textureId_);
glPixelStorei(GL_PACK_ALIGNMENT, 1);
glReadPixels(0, 0, width, height, GL_RGBA, GL_FLOAT, pixels);
glBindTexture(GL_TEXTURE_1D, 0);

buw::Image_4f::Ptr img(new buw::Image_4f(width, height, pixels));

buw::storeImageAsFile(filename.toCString(), img.get());

delete pixels;

但是返回的像素数据与输入像素数据不同(输入:彩色斜坡，ouptut:黑色图像)

有什么办法解决这个问题吗？也许我使用了错误的API调用。

Answer 1

用glReadPixels替换glGetTexImage确实解决了这个问题。