gravy | A WebGL simulation of gravitational lensing | Animation library
kandi X-RAY | gravy Summary
kandi X-RAY | gravy Summary
Click below for live demos, and author your own via the API. In the presence of a sufficiently strong gravitational field (produced by large amounts of matter, e.g. stars, galaxies, and dark matter), space is curved and causes light rays to be deflected towards matter. This produces a focusing effect which is known as gravitational lensing, where luminous objects behind a distribution of mass appear to be distorted. Gravy simulates this effect, in order to show the paths which the light follows. A large number of simulated rays are emitted from a light source, and the curved path of each drawn. When enough paths have been drawn, the resulting image converges to a visualization of the amount of light energy everywhere in space in the steady state. There is a single light source, a disk with a variable beam angle, directed along the negative x-axis. The mass distribution is specified in the form of the 3d gravitational potential, via GLSL code. The simulation makes the assumption that the gravitational field is not so strong that the full effects of general relativity need to be taken into account. In this approximation, the effect is exactly analogous to refraction, with the refractive index of space driven by the local gravitational potential. The approximation breaks down sufficiently close to large masses however. In fact in classic lensing systems in astronomy (galactic lensing or microlensing) the angular deflection is actually very small, on the order of arcminutes at most. (Also, there are cosmological effects involved because the distances are so large). In the examples shown here, the lensing is much stronger, producing large angular deflections, even causing the light to bend into loops. This would only happen in reality if the light source is positioned close to a massive compact object like a black hole or neutron star. Strictly speaking a full general relativistic simulation is needed in this scenario, but the simulation can at least be considered a first order approximation. Note also that technically, there should be factors of the gravitational constant and the speed of light involved (e.g. the potential has units of speed of light squared). These constants have been effectively set to 1, so the lengths are in units related to the Schwarzschild radius of the system. As Gravy is not intended to be a fully scientifically accurate simulation, this seems a reasonable approach. There is an experimental system for visualizing with color bands the "time delay" along each light path. In this effect, the total time each light ray takes to travel from source to observer is different, both due to the curving of the path, and also due to time dilation (the so-called Shapiro delay).
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QUESTION
I hit a wall with this one so looking for help.
My strings must be in the following format:
...ANSWER
Answered 2021-May-11 at 14:57You can use
QUESTION
I am very new to Json parsing. I have to iterate throught json array object.
my JSON class:
...ANSWER
Answered 2021-May-10 at 07:25This is what I meant by iterating over the length of the lists, I have added a code from where you can get an idea of how you can parse.
UPDATED CODE
QUESTION
Here is the code I currently have:
...ANSWER
Answered 2021-Feb-12 at 15:15There are some mistakes in your code, try the following instead:
QUESTION
When I run powershell using invoke-webrequest on a URL without an ampersand everything works.
But my URL's have ampersands in them. If I surround them by double quotes it works from PowerShell, but not if I am doing it through my SQL Server.
Trying to get the right combination of escape characters is proving to be a pain in the butt. Here's an example of the command:
...ANSWER
Answered 2020-Dec-16 at 20:34Add embedded "..."-quoting to the URL, which requires escaping as \"...\":
QUESTION
I've started learning typescript from the official documentation, and came across the topic of intersecting types. So, in order to get a proper understanding of how type intersection works, i decided to write up a custom type. The FoodItems interface requires to be an array of objects and same for side. However, whenever I try intersect the two types, every representation of FoodOrder fails. I don't understand why that happens and what i'm doing wrong.
...ANSWER
Answered 2020-Sep-16 at 13:19An intersection type requires food to be both a valid FoodItems object and a valid FoodSide object.
Remember: an intersection type I = A & B means that the set of values of type I is the intersection of the sets of the values of types A and B. Since every value of type I is at the same time a valid A and a valid B, it follows that the properties of the intersection type I must be the union of the properties of the types A and B.
Likewise, a union type U = A | B means that the set of values of type U is the union of the sets of the values of types A and B. Since every value of type U is either a valid A or a valid B, it follows that the properties of the union type U must be the intersection of the properties of the types A and B.
So, what you are saying is that FoodOrder is a type which can be indexed by a number and it returns a FoodItems but at the same time it also returns a FoodSide when it is indexed by a number.
A value of such a type cannot exist, so you actually can't construct anything that would be legal to assign to food.
What would be possible is something like this:
QUESTION
I have a file1 with several variables defined:
...ANSWER
Answered 2020-Sep-04 at 21:16You can do the following:
QUESTION
I want to create an R function that inserts a "\n" after every n words in a string (where n is an argument).
e.g.
...ANSWER
Answered 2020-May-13 at 13:04You can use gsub to create an R function that inserts a "\n" after every n words, where n is an argument.
QUESTION
I have the following switch/case statement which returns data from the json object below. In reality this will be very long!
Switch statement
...ANSWER
Answered 2020-Apr-09 at 15:52Is this what you need?
QUESTION
I'm confused on the point of React.forwardRef. As explained in its documentation, I understand that its main use is for a parent to gain access to DOM elements of the child. But I can already do that without even having to use it.
Here is a code example that you can plug into codeSandbox and see that it works:
...ANSWER
Answered 2020-Mar-31 at 23:57You're absolutely right that you can do what you've described. The downside is that you're forced to expose an API (ie: the fRef prop) for it to work. Not a huge deal if you're a solo developer building an app, but it can be more problematic eg. if you're maintaining an open-source library with a public API.
In that case, consumers of the library won't have access to the internals of a component, meaning you'd have to expose it for them somehow. You could simply do what you're suggesting in your example and add a named prop. In fact, that's what libraries did before React 16.3. Not a huge deal, but you'd have to document it so people know how to use it. Ideally, you'd also want some kind of standard that everyone used so it wasn't confusing (many libraries used the innerRef naming convention), but there'd have to be some consensus around that. So all doable, but perhaps not the ideal solution.
Using forwardRef, passing a ref to a component just works as expected. The ref prop is already standardized in React, so you don't need to go look at docs to figure out how to pass the ref down or how it works. However, the approach you describe is totally fine and if it meets your needs, by all means go with that.
QUESTION
I have two list of lists which looks like the following
...ANSWER
Answered 2020-Mar-10 at 21:23You can try , notice I am adding groupby and head due to your ingre_list have duplicated item within each sub-list, if in real data there is no duplicates , you can remove .groupby(level=0).head(1)
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