OpenGL C++鼠标光线拾取glm:unproject

Question

我目前正在研究C++游戏引擎,我想在应用程序中构建鼠标交互.我以前通过射线拾取完成了这个,但是当时我使用了固定的鼠标位置,现在我想不用它.我读到你可以使用glm :: unProject函数来做到这一点,但我的工作不起作用.coördinates这个功能给出了不对.我究竟做错了什么？

rscore_projection_matrix = glm::perspective(45.0f, (float)(windowWidth)/(float)(windowHeight), 0.1f, 1000.0f);
rscore_view_matrix = glm::lookAt(glm::vec3(lengthdir_x(16, rscam_direction)+rscam_x, rscam_z, lengthdir_y(16, rscam_direction)+rscam_y), glm::vec3(rscam_x, 0, rscam_y), glm::vec3(0,1,0));
rscore_model_matrix = glm::mat4(1.0f);
glm::vec3 screenPos = glm::vec3(rscore_mouse_x, rscore_mouse_y, 0.1f);
glm::vec4 viewport = glm::vec4(0.0f, 0.0f, windowWidth, windowHeight);
glm::vec3 worldPos = glm::unProject(screenPos, rscore_model_matrix, rscore_projection_matrix, viewport);

我使用vec3 worldPos位置来绘制对象.

Answer 1

不确定这是否会对你有所帮助,但我通过这种方式实现射线拾取(计算射线的方向):

glm::vec3 CFreeCamera::CreateRay() {
    // these positions must be in range [-1, 1] (!!!), not [0, width] and [0, height]
    float mouseX = getMousePositionX() / (getWindowWidth()  * 0.5f) - 1.0f;
    float mouseY = getMousePositionY() / (getWindowHeight() * 0.5f) - 1.0f;

    glm::mat4 proj = glm::perspective(FoV, AspectRatio, Near, Far);
    glm::mat4 view = glm::lookAt(glm::vec3(0.0f), CameraDirection, CameraUpVector);

    glm::mat4 invVP = glm::inverse(proj * view);
    glm::vec4 screenPos = glm::vec4(mouseX, -mouseY, 1.0f, 1.0f);
    glm::vec4 worldPos = invVP * screenPos;

    glm::vec3 dir = glm::normalize(glm::vec3(worldPos));

    return dir;
}

// Values you might be interested:
glm::vec3 cameraPosition; // some camera position, this is supplied by you
glm::vec3 rayDirection = CFreeCamera::CreateRay();
glm::vec3 rayStartPositon = cameraPosition;
glm::vec3 rayEndPosition = rayStartPosition + rayDirection * someDistance;

说明:

将Vertice的位置与View和Projection矩阵相乘时,您将获得像素位置.如果将像素位置与View和Projection矩阵的反转相乘,那么您将获得世界的位置.

虽然计算逆矩阵很昂贵,但我不确定glm :: unProject是如何工作的,它可能会做同样的事情.

这只会为您提供面向世界的光线方向(您应该已经拥有相机的位置).此代码不与对象"冲突".

摄像机课程的其余部分代码就在这里.

可以在这里找到更多信息 - 例如 - .