Manual Content: delta_time() example should not use hardcoded microseconds value

[gm-bug-reporter]

Description

The manual's example of delta time is incorrect and will confuse users not used to programming with delta time in mind.

Expected Change

The example should be corrected to:

var _dt = delta_time / game_get_speed(gamespeed_microseconds);
speed = spd * _dt;

Manual Link

https://manual.gamemaker.io/monthly/en/#t=GameMaker_Language%2FGML_Reference%2FMaths_And_Numbers%2FDate_And_Time%2Fdelta_time.htm

Which version of GameMaker are you reporting this issue for?

IDE v2024.8.1.171 Runtime v2024.8.1.218

Which operating system(s) are you seeing the problem on?

Windows 10.0.19045.0

ba0f23b0-fb20-46d3-bf0c-301c6a91b8cb

[DragoniteSpam]

The example is "correct," but it lacks context.

In a 60 fps game, the manual example resolves to 16_666 / 1_000_000, or 0.016, which is fine if spd is a value defined in units/second.

Your example resolves to 16_666 / 16_666, or 1, which is fine if spd is a value defined in units/frame.

Ideally the manual should explain both.

[mistletoe]

It be simpler to simply have a hard-coded standard value.

I've been using globals like these:

global.microSecond = 1000000.0;
global.microSecondOverOne = 1/global.microSecond;//Used when we want to use this as a cheap multiplier, etc.

There should probably be some standard variables, like

micro_second = 1000000.0;
micro_second_over_one = 1/1000000.0;

It's arguable that there should be a micro_second_per_step, as well, which is just returning game_get_speed(gamespeed_microseconds). It's just syntactic sugar, though.

For most games, this value's set once and only once, but it gets tricky when you're doing things like time warping, etc.

[YYBartT]

Changed the ratio _dt in the code example to delta_time / game_get_speed(gamespeed_microseconds). Added the original code example as Example 2, since the multiplication does convert a base speed in pixels per second to one in pixels per step in that case.