alice-teacher Screen flickers when moving accellerating camera

[Vanderhyde, James]

Don, thanks. Decreasing the duration does cause less flicker. But it also changes the nice feel of acceleration and deceleration caused by the stacking up of the key events. The duration is the amount of time it takes to reach top speed, so setting the the duration to 0 causes instantaneous acceleration. It feels very different.

I know Alice 3 is not a game engine, and using stacking up of key events to achieve acceleration is kind of a hack. I don’t know how the students came up with it. I will share this solution with them to see if it is acceptable.

James
—
James Vanderhyde
Associate Professor and Department Chair
Computer Science
Saint Xavier University
3700 W. 103rd St.
Chicago, IL 60655
773-298-3454

On Apr 20, 2021, at 7:51 AM, Donald Slater via alice-teachers <alice-teachers at lists.andrew.cmu.edu<mailto:alice-teachers at lists.andrew.cmu.edu>> wrote:

James,
From the development Team…

The key repeat speed of 30 per second (per key) combined with the default 1 second animation can stack up a few too many transformations.
They should get less flicker by lowering the duration of each animation to 0.25 or 0.1 second, or even 0. The effective motion won't be much changed.

We are looking at some of the assumptions regarding our defaults. Thank you for bringing this to our attention…

Take care and be well,

Don Slater

Alice Project

On Apr 17, 2021, at 12:27 PM, Vanderhyde, James <vanderhyde at sxu.edu<mailto:vanderhyde at sxu.edu>> wrote:

Some of my students are making car race games. They came up with a way to do player control or the car using the COMBINE option on the keyboard event with a move forward duration 1. It actually has a very nice feel of acceleration, because the combined movement instructions stack up until a max speed is hit due to the fixed frame rate.

However, something weird happens when you set the camera’s vehicle property to the car. The screen flickers as the camera accelerates. I’m attaching an Alice program that exhibits the behavior. Use up arrow to move forward and right arrow to turn. The flicker occurs sporadically, but more frequently if you try turning. The flicker also happens just moving the camera, so it does not seem to be connected to the vehicle. But the vehicle makes it worse, it seems.

Alice 3.6.0.1 +build .500
MacOS Mojave 10.14.6
Intel Core i7
Intel Iris Pro graphics

James
—
James Vanderhyde
Associate Professor and Department Chair
Computer Science
Saint Xavier University
3700 W. 103rd St.
Chicago, IL 60655
773-298-3454
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