[英]Error: qualifiers dropped in binding reference of type “blah blah” to initialize “some other blah blah”
所以,当我在线程外创建“boxes”和“boxbound”变量时出现运行时错误,但是当我将它移到线程内的for循环内时,错误消失了,这可能是什么原因?
void Flyscene::raytraceScene(int width, int height) {
std::cout << "ray tracing ..." << std::endl;
//start of acceleration structure
std::vector<std::vector<Tucano::Face>> boxes = firstBox(mesh);
std::vector<std::vector<Eigen::Vector3f>> boxbounds;
for (int i = 0; i < boxes.size(); i++) {
boxbounds.push_back(getBoxLimits(boxes[i], mesh));
}
/////
// if no width or height passed, use dimensions of current viewport
Eigen::Vector2i image_size(width, height);
if (width == 0 || height == 0) {
image_size = flycamera.getViewportSize();
}
// create 2d vector to hold pixel colors and resize to match image size
vector<vector<Eigen::Vector3f>> pixel_data;
pixel_data.resize(image_size[1]);
for (int i = 0; i < image_size[1]; ++i)
pixel_data[i].resize(image_size[0]);
// origin of the ray is always the camera center
Eigen::Vector3f origin = flycamera.getCenter();
Eigen::Vector3f screen_coords;
// Multi Threading
// Comment this if you don't want multi-threading
//-----------------------------------------------------//
int max_pixels = (image_size[0] * image_size[1]); //width * height
// Get amount of cores of your CPU
int cores = std::thread::hardware_concurrency();
// Keep track of # of pixels (atomic making sure no 2 threads render the same pixel)
volatile std::atomic<std::size_t> curr_pixel(0);
// Stores all cores assigned to a task
std::vector<std::future<void>> future_vector;
cout << "Threads supported: " << cores << "\n";
while (cores--)
future_vector.emplace_back(
std::async([=, &origin, &curr_pixel, &pixel_data]()
{
while (true)
{
int index = curr_pixel++;
if (index >= max_pixels)
break;
std::size_t i = index % image_size[1];
std::size_t j = index / image_size[1];
//cout << "at index: " << index << std::endl;
// create a ray from the camera passing through the pixel (i,j)
auto screen_coords = flycamera.screenToWorld(Eigen::Vector2f(i, j));
// launch raytracing for the given ray and write result to pixel data
pixel_data[i][j] = traceRay(0,origin, screen_coords, boxes, boxbounds);
if (index % 10000 == 0) {
std::cout << "Percentage done (mt): " << (float)(index / 10000) << "%" << std::endl;
}
}
}));
// Call futures (Async jobs), this will activate all process on the cores
for (auto& e : future_vector) {
e.get();
}
但是,当我将它移到下面时,错误消失了;
void Flyscene::raytraceScene(int width, int height) {
std::cout << "ray tracing ..." << std::endl;
// if no width or height passed, use dimensions of current viewport
Eigen::Vector2i image_size(width, height);
if (width == 0 || height == 0) {
image_size = flycamera.getViewportSize();
}
// create 2d vector to hold pixel colors and resize to match image size
vector<vector<Eigen::Vector3f>> pixel_data;
pixel_data.resize(image_size[1]);
for (int i = 0; i < image_size[1]; ++i)
pixel_data[i].resize(image_size[0]);
// origin of the ray is always the camera center
Eigen::Vector3f origin = flycamera.getCenter();
Eigen::Vector3f screen_coords;
// Multi Threading
// Comment this if you don't want multi-threading
//-----------------------------------------------------//
int max_pixels = (image_size[0] * image_size[1]); //width * height
// Get amount of cores of your CPU
int cores = std::thread::hardware_concurrency();
// Keep track of # of pixels (atomic making sure no 2 threads render the same pixel)
volatile std::atomic<std::size_t> curr_pixel(0);
// Stores all cores assigned to a task
std::vector<std::future<void>> future_vector;
cout << "Threads supported: " << cores << "\n";
while (cores--)
future_vector.emplace_back(
std::async([=, &origin, &curr_pixel, &pixel_data]()
{
while (true)
{
int index = curr_pixel++;
if (index >= max_pixels)
break;
std::size_t i = index % image_size[1];
std::size_t j = index / image_size[1];
//cout << "at index: " << index << std::endl;
//start of acceleration structure
std::vector<std::vector<Tucano::Face>> boxes = firstBox(mesh);
std::vector<std::vector<Eigen::Vector3f>> boxbounds;
for (int i = 0; i < boxes.size(); i++) {
boxbounds.push_back(getBoxLimits(boxes[i], mesh));
}
/////
// create a ray from the camera passing through the pixel (i,j)
auto screen_coords = flycamera.screenToWorld(Eigen::Vector2f(i, j));
// launch raytracing for the given ray and write result to pixel data
pixel_data[i][j] = traceRay(0,origin, screen_coords, boxes, boxbounds);
if (index % 10000 == 0) {
std::cout << "Percentage done (mt): " << (float)(index / 10000) << "%" << std::endl;
}
}
}));
// Call futures (Async jobs), this will activate all process on the cores
for (auto& e : future_vector) {
e.get();
}
这也是 rayTrace 方法:
Eigen::Vector3f Flyscene::traceRay(int level, Eigen::Vector3f& origin, Eigen::Vector3f& dest, std::vector<std::vector<Tucano::Face>>& boxes, std::vector<std::vector<Eigen::Vector3f>>& boxbounds)
你为什么认为这是?
这是完整的错误描述:
错误(活动)E0433 限定符在类型“std::vector>、std::allocator>>> &”的绑定引用中丢弃到类型为“const std::vector>、std::allocator>>>”的初始化程序
错误(活动)E0433 限定符在类型“std::vector>、std::allocator>>> &”的绑定引用中丢弃到类型为“const std::vector>、std::allocator>>>”的初始化程序
您需要将mutable
添加到 lambda。
向量通过引用传递(到traceRay
),因此可以在此 function 中修改它们。 您的 lambda 通过复制=
获取向量(用于捕获),通过=
捕获的 object 只能读取,您不能修改它们。
您的代码可以简化为以下示例:
void bar(std::vector<int>& v) {
}
void foo() {
std::vector<int> v;
auto l = [=]() /*mutable*/
{
bar(v); // works only with uncommented mutable
// v can be modified only with mutable
};
l();
}
当您在 lambda 中创建向量时,它们不会被捕获,因此您可以在traceRay
中更改它们。
因此,在第一个片段中,您添加了mutable
:
std::async([=, &origin, &curr_pixel, &pixel_data]() mutable
{ ^^^^^^^
while (true)
{
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