Edit3：我的问题与我预期的功能完全不同。生病让代码停留，也许这有助于某人:)（并且不要忘记调试！）。
我试图找到一条线与三角形相交的矢量。
当前状态：即使鼠标不在地板上且摄像机视图依赖（随机矩阵），也会出现随机交叉点
步骤
取消鼠标协调
我检查了glm :: unproject和gluUnproject的来源并创建了这个函数。
pixel::CVector3 pixel::CVector::unproject(
CVector2 inPosition,
pixel::CShape window,
pixel::matrix4 projectionMatrix,
pixel::matrix4 modelViewMatrix,
float depth
)
{
// transformation of normalized coordinates
CVector4 inVector;
inVector.x = (2.0f * inPosition.x) / window.width - 1.0f;
inVector.y = (2.0f * inPosition.y) / window.height - 1.0f;
inVector.z = 2.0f * depth - 1.0f;
inVector.w = 1.0f;
// multiply inverted matrix with vector
CVector4 rayWorld = pixel::CVector::multMat4Vec4(pixel::CMatrix::invertMatrix(projectionMatrix * modelViewMatrix), inVector);
CVector3 result;
result.x = rayWorld.x / rayWorld.w;
result.y = rayWorld.y / rayWorld.w;
result.z = rayWorld.z / rayWorld.w;
return result;
}
检查交叉路口
pixel::CVector3 pixel::Ray::intersection(
Ray ray,
pixel::CVector3 v0,
pixel::CVector3 v1,
pixel::CVector3 v2
)
{
// compute normal
CVector3 a, b, n;
a = v1 - v0;
b = v2 - v0;
n = ray.direction.cross(b);
// find determinant
float det = a.dot(n);
if (det < 0.000001f)
{
std::cout << "Ray intersecting with backface triangles \n";
return pixel::CVector::vector3(0.0f, 0.0f, 0.0f);
}
det = 1.0f / det;
// calculate distance from vertex0 to ray origin
CVector3 s = ray.origin - v0;
float u = det * s.dot(n);
if (u < -0.000001f || u > 1.f + 0.000001f)
{
std::cout << "U: Intersection outside of the triangle!\n";
return pixel::CVector::vector3(0.0f, 0.0f, 0.0f);
}
CVector3 r = s.cross(a);
float v = det * ray.direction.dot(r);
if (v < -0.000001f || u + v > 1.f + 0.000001f)
{
std::cout << "V/U: Intersection outside of triangle!\n";
return pixel::CVector::vector3(0.0f, 0.0f, 0.0f);
}
// distance from ray to triangle
det = det * b.dot(r);
std::cout << "T: " << det << "\n";
CVector3 endPosition;
endPosition.x = ray.origin.x + (ray.direction.x * det);
endPosition.y = ray.origin.y + (ray.direction.y * det);
endPosition.z = ray.origin.z + (ray.direction.z * det);
return endPosition;
}
用法
if (event.button.button == SDL_BUTTON_RIGHT)
{
camera->setCameraActive();
float mx = event.motion.x;
float my = window->info.height - event.motion.y;
// ray casting
pixel::Ray ray;
std::cout << "\n\n";
// near
pixel::CVector3 rayNear = pixel::CVector::unproject(
pixel::CVector::vector2(mx, my),
pixel::CVector::shape2(window->info.internalWidth, window->info.internalHeight),
camera->camInfo.currentProjection,
camera->camInfo.currentView,
1.0f
);
// far
pixel::CVector3 rayFar = pixel::CVector::unproject(
pixel::CVector::vector2(mx, my),
pixel::CVector::shape2(window->info.internalWidth, window->info.internalHeight),
camera->camInfo.currentProjection,
camera->camInfo.currentView,
0.0f
);
// normalized direction results in the same behavior
ray.origin = cameraPosition;
ray.direction = pixel::CVector::normalize(rayFar- rayNear);
std::cout << "Raycast \n";
std::cout << "Mouse Position: " << mx << " - " << my << "\n";
std::cout << "Camera Position: " << ray.origin.x << " - " << ray.origin.y << " - " << ray.origin.z << "\n";
std::cout << "Ray direction: " << ray.direction.x << " - " << ray.direction.y << " - " << ray.direction.z << "\n";
pixel::CVector3 vertOne = pixel::CVector::vector3(0.0f, 0.0f, -300.0f);
pixel::CVector3 vertTwo = pixel::CVector::vector3(0.0f, 0.0f, 0.0f);
pixel::CVector3 vertThree = pixel::CVector::vector3(300.0f, 0.0f, 0.0f);
pixel::CVector3 vertFour = pixel::CVector::vector3(300.0f, 0.0f, -300.0f);
pixel::CVector3 rayHit = pixel::Ray::intersection(ray, vertOne, vertTwo, vertThree);
pixel::CVector3 rayHit2 = pixel::Ray::intersection(ray, vertThree, vertFour, vertOne);
std::cout << "Ray hit: " << rayHit.x << " - " << rayHit.y << " - " << rayHit.z << "\n";
std::cout << "Ray hit: " << rayHit2.x << " - " << rayHit2.y << " - " << rayHit2.z << "\n";
std::cout << "--------------------\n";
towerHouse->modelMatrix = pixel::CMatrix::translateMatrix(rayHit);
输出
由于我从未使用过glm :: unproject或gluUnproject，我不知道正常输出应该是什么样子，但我得到的结果如下：
射线方向：0.109035 -0.0380502 0.0114562
看起来不对我，但是检查我的代码与其他来源（如上所述），我没有看到错误/ s。
Ray交叉点在某些特殊情况下工作（相机旋转），即使我没有点击地板，我也会得到交叉点。 交叉口输出从背面碰撞到三角形外部也是如此。
所有这些错误看起来像问题的主要来源是不投影。
正确方向的任何提示？
答案 0 :(得分：1)
这个问题的答案无处可寻，但这在评论或聊天中难以解释。
首先：
// near
pixel::CVector3 rayNear = pixel::CVector::raycast(
pixel::CVector::vector2(mx, my),
pixel::CVector::shape2(window->info.internalWidth, window->info.internalHeight),
camera->camInfo.currentProjection,
camera->camInfo.currentView,
1.0f // WRONG
);
// far
pixel::CVector3 rayFar = pixel::CVector::raycast(
pixel::CVector::vector2(mx, my),
pixel::CVector::shape2(window->info.internalWidth, window->info.internalHeight),
camera->camInfo.currentProjection,
camera->camInfo.currentView,
0.0f // WRONG
);
窗口空间中的 0.0 ，远 1.0 （取决于深度范围，但如果您更改了深度范围，则应该已经知道这一点）。
在光线投射功能中，您有：
CVector3 result;
result.x = rayWorld.x / rayWorld.w;
result.y = rayWorld.y / rayWorld.w;
result.z = rayWorld.z / rayWorld.w;
w == 0.0有可能，此时结果还不是光线......它是 对象空间中的位置 （不是世界）。通常，您总是会使用性能良好的矩阵，但是如果您查看UnProject (...)的正式实现，您会注意到它们处理w == 0.0具有特殊返回值的情况或者设置状态标志。
pixel::CVector3 vertOne = pixel::CVector::vector3(0.0f, 0.0f, -300.0f);
pixel::CVector3 vertTwo = pixel::CVector::vector3(0.0f, 0.0f, 0.0f);
pixel::CVector3 vertThree = pixel::CVector::vector3(300.0f, 0.0f, 0.0f);
pixel::CVector3 vertFour = pixel::CVector::vector3(300.0f, 0.0f, -300.0f);
这些顶点是什么坐标空间？大概是物体空间，这意味着如果你从相机的视点（在世界空间中定义）投射穿过远平面上的点的光线，并尝试更频繁地测试物体空间中三角形的交点不，你会想念。这是因为每个空间的原点，比例和旋转可能不同。在尝试此测试之前，您需要将这些点转换为世界空间（原始代码的floor->modelMatrix可以很好地用于此目的）。
答案 1 :(得分：1)
我追踪了问题并修复了错误。我有错误的矩阵*矩阵和矩阵*向量乘法运算符。