c++ - OpenGL - 纹理四边形裁剪和奇怪的拉伸(stretch)

Question

我目前正在我的计算机上创建一些像素数据并将其发送到 OpenGL 中的纹理中。我正在写入的导出缓冲区非常好，但是在四边形上渲染为纹理的相同缓冲区却奇怪地扭曲了。我已经更正了 UV，检查了纹理设置，但似乎一切正常。

OpenGL 预览位于右侧。左侧是存储为 RGB 组件的原始缓冲区数据的预览(我使用 rawpixels.net 进行预览)。这与我发送到纹理的数据相同。

int width = 400;
int height = 300;

int main() {
    glfwInit();
    glewInit();

    GLFWwindow* win = glfwCreateWindow(width, height, "", NULL, NULL);
    glfwMakeContextCurrent(win);
    glfwSetWindowAttrib(win, GLFW_RESIZABLE, 0);

    unsigned int tex;
    rgb* canvas = new rgb[width * height];

    graphics g(width, height, canvas);
    g.drawLine(vec2(0, 0), vec2(100, 300), 10, rgb(100, 100, 255));

    float x1 = 255.0 / width;
    float x2 = 255.0 / height;

    for (int i = 0; i < width; ++i) {
        for (int j = 0; j < height; ++j) {
            g.pixel(i, j, rgb(i * x1, j * x1, 255));
        }
    }

    g.drawLine(vec2(0, 0), vec2(100, 300), 10, rgb(255, 50, 20));

    g.saveBuffer("./res/frame.raw");

    glGenTextures(1, &tex);
    glBindTexture(GL_TEXTURE_RECTANGLE, tex);
    glTexImage2D(GL_TEXTURE_RECTANGLE, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, canvas);
    glTexParameteri(GL_TEXTURE_RECTANGLE, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_RECTANGLE, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_RECTANGLE, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_RECTANGLE, GL_TEXTURE_WRAP_T, GL_CLAMP);

    glEnable(GL_TEXTURE_RECTANGLE);

    while (!glfwWindowShouldClose(win)) {
        glfwPollEvents();

        glBegin(GL_QUADS);

        glTexCoord2i(0, 0);
        glVertex2i(-1, 1);

        glTexCoord2i(0, width);
        glVertex2i(-1, -1);

        glTexCoord2i(height, width);
        glVertex2i(1, -1);

        glTexCoord2i(height,0 );
        glVertex2i(1, 1);

        glEnd();

        glfwSwapBuffers(win);
    }

    glDeleteTextures(1, &tex);

    return 0;
}

rgb 只是一个包含 R、G 和 B 组件的结构，存储为无符号字节。graphics 是我创建的类的一个对象。它包含一些将数据写入 Canvas 的方法。

Answer 1

你的 glTexCoord2i 有问题 - x 和 y 被交换了

        glTexCoord2i(height, width); // must be glTexCoord2i(width, height)
        //           ^=======^

这里是固定的:

int width = 400;
int height = 300;

int main() {
    glfwInit();
    glewInit();

    GLFWwindow* win = glfwCreateWindow(width, height, "", NULL, NULL);
    glfwMakeContextCurrent(win);
    glfwSetWindowAttrib(win, GLFW_RESIZABLE, 0);

    unsigned int tex;
    rgb* canvas = new rgb[width * height];

    graphics g(width, height, canvas);
    g.drawLine(vec2(0, 0), vec2(100, 300), 10, rgb(100, 100, 255));

    float x1 = 255.0 / width;
    float x2 = 255.0 / height;

    for (int i = 0; i < width; ++i) {
        for (int j = 0; j < height; ++j) {
            g.pixel(i, j, rgb(i * x1, j * x1, 255));
        }
    }

    g.drawLine(vec2(0, 0), vec2(100, 300), 10, rgb(255, 50, 20));

    g.saveBuffer("./res/frame.raw");

    glGenTextures(1, &tex);
    glBindTexture(GL_TEXTURE_RECTANGLE, tex);
    glTexImage2D(GL_TEXTURE_RECTANGLE, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, canvas);
    glTexParameteri(GL_TEXTURE_RECTANGLE, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_RECTANGLE, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_RECTANGLE, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_RECTANGLE, GL_TEXTURE_WRAP_T, GL_CLAMP);

    glEnable(GL_TEXTURE_RECTANGLE);

    while (!glfwWindowShouldClose(win)) {
        glfwPollEvents();

        glBegin(GL_QUADS);

        glTexCoord2i(0, 0);
        glVertex2i(-1, 1);

        glTexCoord2i(0, height);
        glVertex2i(-1, -1);

        glTexCoord2i(width, height);
        glVertex2i(1, -1);

        glTexCoord2i(width,0 );
        glVertex2i(1, 1);

        glEnd();

        glfwSwapBuffers(win);
    }

    glDeleteTextures(1, &tex);

    return 0;
}