Is Angry Birds deterministic?

[BACK]
Is Angry Birds deterministic?
Posted On: December 21, 2022

While trying to get 3 stars on the more complex levels (the ones with a lot of destructible entities) I noticed that even after playing the same level over 50 times, doing always the same thing, I've never seen the same final result. Something always goes differently.


Does the same input always result in the same output, or is there a random factor in there?


Question from user Andreas Bonini at gaming.stackexchange.com.


Answer:

The algorithm is deterministic, but it's arguable that the overall result of launching a bird is effectively non-deterministic because it relies on (extraordinarily sensitive) user input.


To test the algorithm and the effect user input has on it, I used the following procedure:.


Load the Google Chrome version of Angry Birds.


Load level 1-1.


Pull the mouse back to a specific X-Y coordinate. (This was past the point of "full draw" for the bird.).


Release the bird, and wait for the game to reach a steady state.


To measure my X-Y coordinate, I opened a background Chrome window, and navigated it to this page. I aligned the two windows so that I could see the X and Y positions of the mouse while still able to cause something to happen when I released the bird. I aligned my mouse cursor with the lower left hand corner of the box around these two numbers, and then released. I noted the position of my mouse cursor then (as the display only updates when the mouse is not released and the cursor is over that window) and then noted the resulting score in Angry Birds. If you're having issues with exact mouse positioning, you might try an accessibility option offered by your OS, for instance, Mouse Keys on Windows.


I got the same score, so long as my cursor was in the exact same spot as it was on previous iterations.


Prior to coming up with an enhanced test rig that allowed me to measure my cursor's position to the pixel, I ran this experiment about 10 times, using a reference point in the background image of the game. I got scores by firing the first bird that varied between 8,000 and 11,000 points. Using the enhanced testing strategy, if I was off by a single pixel, I could expect score differences of anywhere between 150 and 500 points. .


I will note that the cursor was beyond the edge of the game area, outside the browser window, far beyond the maximum distance the bird can be drawn back, and I still noticed differences when moving my cursor even a single pixel. .


Further, I took screencaps for an extreme case where my cursor was on a different monitor than the game window, and ran several iterations where I kept my cursor in the same location, or moved it slightly. By my calculations (based on measuring distance from screencaps) the game was able to create a different result (score 32960 vs 31520) based on a one pixel difference in height (544 vs 545 pixels) over a distance of approximately 1,284 pixels of width. This works out to be an angular difference of 0.03 degrees.


I'd say that for any practical purposes, you can expect to employ the same general strategy on the same level repeatedly and expect wildly varying results. The level of sensitivity in the controls is so extreme that there's no practical way to get it to do the same thing twice. This is exacerbated by the fact that if you're playing on a touchscreen, it would be extraordinarily difficult to reproduce the same movements down to the individual pixel.


Answer from user agent86 at gaming.stackexchange.com.



[BACK]
Is Angry Birds deterministic?
Posted On: December 21, 2022

While trying to get 3 stars on the more complex levels (the ones with a lot of destructible entities) I noticed that even after playing the same level over 50 times, doing always the same thing, I've never seen the same final result. Something always goes differently.


Does the same input always result in the same output, or is there a random factor in there?


Question from user Andreas Bonini at gaming.stackexchange.com.


Answer:

The algorithm is deterministic, but it's arguable that the overall result of launching a bird is effectively non-deterministic because it relies on (extraordinarily sensitive) user input.


To test the algorithm and the effect user input has on it, I used the following procedure:.


Load the Google Chrome version of Angry Birds.


Load level 1-1.


Pull the mouse back to a specific X-Y coordinate. (This was past the point of "full draw" for the bird.).


Release the bird, and wait for the game to reach a steady state.


To measure my X-Y coordinate, I opened a background Chrome window, and navigated it to this page. I aligned the two windows so that I could see the X and Y positions of the mouse while still able to cause something to happen when I released the bird. I aligned my mouse cursor with the lower left hand corner of the box around these two numbers, and then released. I noted the position of my mouse cursor then (as the display only updates when the mouse is not released and the cursor is over that window) and then noted the resulting score in Angry Birds. If you're having issues with exact mouse positioning, you might try an accessibility option offered by your OS, for instance, Mouse Keys on Windows.


I got the same score, so long as my cursor was in the exact same spot as it was on previous iterations.


Prior to coming up with an enhanced test rig that allowed me to measure my cursor's position to the pixel, I ran this experiment about 10 times, using a reference point in the background image of the game. I got scores by firing the first bird that varied between 8,000 and 11,000 points. Using the enhanced testing strategy, if I was off by a single pixel, I could expect score differences of anywhere between 150 and 500 points. .


I will note that the cursor was beyond the edge of the game area, outside the browser window, far beyond the maximum distance the bird can be drawn back, and I still noticed differences when moving my cursor even a single pixel. .


Further, I took screencaps for an extreme case where my cursor was on a different monitor than the game window, and ran several iterations where I kept my cursor in the same location, or moved it slightly. By my calculations (based on measuring distance from screencaps) the game was able to create a different result (score 32960 vs 31520) based on a one pixel difference in height (544 vs 545 pixels) over a distance of approximately 1,284 pixels of width. This works out to be an angular difference of 0.03 degrees.


I'd say that for any practical purposes, you can expect to employ the same general strategy on the same level repeatedly and expect wildly varying results. The level of sensitivity in the controls is so extreme that there's no practical way to get it to do the same thing twice. This is exacerbated by the fact that if you're playing on a touchscreen, it would be extraordinarily difficult to reproduce the same movements down to the individual pixel.


Answer from user agent86 at gaming.stackexchange.com.



[BACK]

Is there a secret way to get some character skins in Soul Knight? Is there a secret way to get some character skins in Soul Knight?

Posted On: August 19, 2023
I'm quite new to playing Soul Knight, and I find it quite enjoyable and entertaining. I see that there are skins in the game, but I just can't afford to buy one. Is there a secret thing o...[More]


Can I disable DLC in Dead Cells? Can I disable DLC in Dead Cells?

Posted On: April 6, 2023
I purchased Dead Cells on Steam with all the DLC and am finding the experience to be overwhelming. Can I disable the DLC to only play with the original content? If yes, how would disabling the DLC imp...[More]


Whats a good strategy to get the Flower Power achievement? Whats a good strategy to get the Flower Power achievement?

Posted On: August 5, 2023
I'm playing Plants vs. Zombies on the iPhone and one of the achievements is "Flower Power: Keep 10 Twin Sunflowers Alive in a Single Level". I've tried on many different levels &mdas...[More]


Oof Oof

Posted On: December 17, 2024
Question from user Ferocs at BaldursGate3 at reddit.com.Answer:the issue with wylls story was not lack of effort. he has a ton of characters and narrative beats, its just not very engaging for enough ...[More]


Unsupported resolution in Mirrors Edge Unsupported resolution in Mirrors Edge

Posted On: January 24, 2023
I just installed the game, Mirror's Edge but unfortunately my LCD monitor isn't supporting its default resolution. My LCD monitor's resolution is 1024x768 60Hz. Question from user Te...[More]


Is there any way into the Abandoned the Zelda Hebra Mine forge tower? Is there any way into the Abandoned the Zelda Hebra Mine forge tower?

Posted On: July 7, 2023
In the Abandoned Hebra Mine, on top of the forge construct tower there is some unusual smoke coming out of the chimney. Is there any way into this tower? Or is there nothing more to it?. I've d...[More]


How do I take down a ufo without damaging it? How do I take down a ufo without damaging it?

Posted On: November 28, 2023
I've been looking for a way to take down a UFO without doing any (or little damage) to it as possible. I haven't found any research that would help me either. My question is, is there some wea...[More]


Is there an odds calculator for the starting hand in YuGiOh Master Duel? Is there an odds calculator for the starting hand in YuGiOh Master Duel?

Posted On: March 10, 2023
I play a Blue Eyes deck (handtraps count is still not complete) of 40 cards, here is my main deck list. BEWD x3. Sage with Eyes of Blue x3. White Stone of the Ancients x3. Maxx "C&quo...[More]


How can I teleport to an unloaded entity in Minecraft? How can I teleport to an unloaded entity in Minecraft?

Posted On: June 21, 2023
I am using invisible invulnerable ArmorStands to create "warps" and "homes" in a map. The idea is that I can spawn them in with a specific name, and then teleport a player back to ...[More]


[Warning: Spoiler] I feel so alone in liking Natsai in Hogwarts [Warning: Spoiler] I feel so alone in liking Natsai in Hogwarts

Posted On: June 24, 2023
I feel like I'm in the twilight zone because I seem to be liking characters in this game that aren't liked by most players. I like Natty the most, and then Ominis and Poppy. Though Poppy is...[More]