kuligs2 what is even double precision? like x.xx?
I gave a link to the article above.
This is the range where individual integer values can be represented in a floating-point number:
- Single-precision float range (represent all integers): Between -16,777,216 and 16,777,216
- Double-precision float range (represent all integers): Between -9 quadrillon and 9 quadrillon
It is needed for astronomical calculations
Tomcat i get that it is needed for astro stuff.. but can you not abstracterize the numbers? like you want something with 100 zeros you just write it like maybe 1e100 then do some conversion maths from string/obj to some number and or something.. i mean you dont have to store the whole number in a var or do you? i mean 5 chars in a string is less bytes than 1 with 100 zeros..??
kuligs2 like you want something with 100 zeros you just write it like maybe 1e100 then do some conversion maths from string/obj to some number and or something
That's possible, but it would make the math calculations extremely slow. And you wouldn't be able to use Godot's built-in features like CharacterBody3D, collisions and the physics engine.
Godot's primitive float variables and floating point operations are already double precision. The problem is that when using built-in objects such as CharacterBody3D in a standard Godot build, the position, velocity and other properties get truncated to single precision. So you would have to avoid using those objects, and do your own physics calculations.
Maybe the ideal solution is a double precision physics engine plugin.
I wonder how Unity and Unreal handle this.
For those interested the discussion about releasing an official build with double precision can be found here:
https://github.com/godotengine/godot-proposals/issues/5610
For the reverseZ(better depth buffer) topic read this:
https://godotengine.org/article/introducing-reverse-z/
kuligs2 but can you not abstracterize the numbers?
That's not really my topic. I just joined the discussion of Godot compilation possibilities with extended non-standard features. Although my project may need large numbers, but this is in the very long term. Then I will look for a solution.
DaveTheCoder Maybe the ideal solution is a double precision physics engine plugin.
Can a plugin replace the built-in solution? I'm interested in the question "in general" — I came across a statement that the physics engine should be integrated into the kernel and an extension won't help in this situation.
Keep in mind that even if you have double-precision values in your app, the GPU rendering hardware is still single-precision. It's going to convert all your nice double-precision values back into single-precision.
Tomcat This is the article that disagrees with you:
Lol. The guy moved a scene that's several units big, 10000 units from the origin. That's a very naive bruteforce way to render it. If you plan to render a galaxy this way, not even quadruple precision will help you. Some form of coordinate localization approach should always be used with large spaces, and if you do it right the single precision will always be enough while player would still have the illusion that they deal with a huge continuum.
As I always say: don't do simulations in games, do illusions of simulations. It'll spare you much headache.
xyz Lol. The guy moved a scene that's several units big, 10000 units from the origin. That's a very naive bruteforce way to render it.
Even I realize this is imagery and a stretch to illustrate the problem.
As I always say: don't do simulations in games, do illusions of simulations.
The question is: where is the line between simulation and imitation? Calculating and showing are different tasks.
If it is possible to achieve double precision in the engine, why do need to avoid it so energetically?
Tomcat If it is possible to achieve double precision in the engine, why do need to avoid it so energetically?
@Haystack Already said why. GPUs (means rendering) operate optimally in single precision. So rendering something that has big coordinates will always "fail". You need to translate it "near" origin for rendering. With sufficiently large distances you'll have the same problem with doubles as well. So a fully generalized solution is not to increase precision, but rather to localize your space representation. How to do it specifically may wary depending on the needs of your "simulation".
The problem really is not in precision. The problem is that people do not understand actual hardware limitations. Today's relatively powerful hardware spoiled them to feel entitled to bruteforce their way out of absolutely everything.
xyz The problem really is not in precision. The problem is that people do not understand actual hardware limitations.
Well, let people learn from their experiences. It's always more useful than outside advice. Warned about possible problems and difficulties, right? And then the person will decide whether to make up his own mind or listen to the wise.
"You can be absolutely right, but what's the point if the user is crying?"
GPUs (means rendering) operate optimally in single precision.
Oh it's worse than that. Some parts of the 3d rendering pipeline hardware only work at single precision. Your vertex geometry will be transformed, clipped, culled, rasterized and depth-tested in single precision. There is no double-precision for these steps.
Modern GPUs can do double-precision in the shaders, but the fixed-function 3d pipeline is still fp32.
