Stb_image 创建奇怪的工件

Question

您好，我正在为我的 openGL 项目制作图像和纹理 class，当我添加 stb_image 时，一些纹理开始在图像边缘添加噪点。

图片class:

    Image::Image() {
        width = 0;
        height = 0;
        channels = 0;
        data = NULL;
    }

    Image::Image(const Image& image) {
        width = image.width;
        height = image.height;
        channels = image.channels;

        int allocation = image.width * image.height * image.channels;
        data = new unsigned char[allocation];
        std::memcpy(data, image.data, allocation);
    }

    Image& Image::operator=(const Image& image) {
        if (this != &image && image.data != nullptr) {
            if(data != NULL)
                delete[] data;
            data = NULL;

            int allocation = image.width * image.height * image.channels;
            data = new unsigned char[allocation];
            std::memcpy(data, image.data, allocation);

            width = image.width;
            height = image.height;
            channels = image.channels;
            filepath = image.filepath;
        }

        return *this;
    }

    Image::Image(const std::string& _filepath) {
        width = 0;
        height = 0;
        channels = 0;
        data = NULL;
        filepath = _filepath;

        data = stbi_load(filepath.c_str(), &width, &height, &channels, STBI_rgb_alpha);
        
        if (data == NULL) {
            Debug::systemErr("Couldn't load image: " + filepath);
        }
    }

    Image::~Image() {
        if (data != NULL) {
            delete[] data;
        }

        data = NULL;
    }

    bool Image::hasData() const{
        return (data != NULL);
    }

纹理class：

Texture::Texture() {
        textureID = 0;
    }

    Texture::Texture(const Texture& texture) {
        image = Image(texture.image);
        textureID = 0;
    }

    Texture::Texture(const std::string& path) {
        image = Image(path);
        textureID = 0;
    }

    Texture& Texture::operator=(const Texture& texture) {
        textureID = texture.textureID;
        image = texture.image;

        return *this;
    }

    Texture::~Texture() {
        destroy();
    }

    void Texture::destroy() {
        glDeleteTextures(1, &textureID);
    }

    void Texture::create() {
        if (!isCreated && image.hasData()) {

            glGenTextures(1, &textureID);
            glBindTexture(GL_TEXTURE_2D, textureID);

            //glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, image.width, image.height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image.data);

            glGenerateMipmap(GL_TEXTURE_2D);

            isCreated = true;
        }
    }

图像为 128x128 像素

这是 paint.net 中的样子：

这是渲染后的样子：

我相信图像加载没问题，因为我用图像 class 设置了 window 的图标，看起来不错。我认为问题出在纹理 class.

已解决 感谢 Jérôme Richard 为我解决了这个问题。这不起作用的原因是即使我将 rgba 设置为通道，图像仍然以 rgb 返回。然后当我尝试复制数据时，而不是为大小做 4 * width * height 。我会做 3 * 宽度 * 高度。所以在 stbi_load() 之后，我只是把 channels = 4.

Answer 1

您应该更仔细地阅读 stbi 文档。它就在开头：

   int x,y,n;
   unsigned char *data = stbi_load(filename, &x, &y, &n, 0);
... replace '0' with '1'..'4' to force that many components per pixel
... but 'n' will always be the number that it would have been if you said 0

因此，如果您将 0 以外的任何内容作为最后一个参数传递，那就是您将获得的频道数。在这种情况下，您应该忽略 n 并按照您请求的频道数进行操作。另一方面，您的代码以另一种方式执行：它请求四个通道，然后使用返回的 n（在您的代码中称为 channels）作为真实来源。

Stb_image 创建奇怪的工件

Stb_image creates weird artifacts

c++

opengl

parsing

textures

image