Adding gravity to sprites in canvas

[Makaya_France-Bray]

I am making a game which the goal is when the user clicks the button, a ball (which is the imageSprite, not the preloaded ball) will move up, generally naturally, and back down with the looks of a gravitational pull. how would i be able to do that without it being glitchy? also ball cannot touch the edges of the canvas or game over.

the only thing I can find is pointInDirection, but it would point the ball and not move it. i think rotate and speed would have to be involved? can i get help on how to implement this

thanks
makaya

[Makaya_France-Bray]

also, how would i be able to toggle a countdown when the start button is pressed, in relation to the ball moving? gravity would have to be implemented first, obviously, but the if-then would be complex ?

[ABG]

See the third link in

FAQ Section: Canvas, Sprites, Balls, Animation

Sprite Origin Docs - @Taifun Scott Ferguson Easing Demo Gravity Exercise from the defunct Scott Ferguson Library Transparent Color Number 16777215 on Canvas - @Ryan_Patridge Fit Canvas to Image using JavaScript - TimAI2 Off Screen Visible Canvas trick - Italo Canvas larger than screen - Scott Ferguson Color extraction - Scott Ferguson Flood Fill - Scott Ferguson Gradients sample - Italo Multi Touch Pixelation - Italo Rotate an ImageSprite on a Canvas Sprite Cannibalism - Scott Fergu…

[ABG]

@Makaya_France-Bray

how would i be able to toggle a countdown

See the second link in

Faq Section: Clock

Guide - How to Use the Clock - Alaqmar Bohori Countdown timers datetime formats How to get UTC with datetime format Z How to keep app running after screen goes off - Taifun Multi-day timer display - Ergin An Instant is not a Duration is not a milliseconds - ABG, TimAI2, Anke You can't store Instants in TinyDB - @Taifun

[Makaya_France-Bray]

would you be able to explain the code blocks in the 2nd link? also how would i be able to keep the ball in the air, as that is another problem.

[ABG]

Please read the chapter on doing animated apps in
http://www.appinventor.org/book2

and do a couple of the animation tutorials.

[Makaya_France-Bray]

okay, thank you. will do.

[Makaya_France-Bray]

would i need to include velocity if the movement is only up and down, or only include speed?

[ABG]

Velocity is the combination of speed and direction, by definition.

Where did you see the term velocity used?

[Makaya_France-Bray]

here, in the first redirect you gave me. i am also using that as guidance.

[Makaya_France-Bray]

this is what i have right now

[ABG]

Try using two global variables, ballSpeedX and ballSpeedY.

Let gravity affect ballSpeedY.

[Makaya_France-Bray]

In that case, would I delete the variable ballSpeed altogether, or would I need a separate speed variable as well? sorry, I'm new to this I'm just trying to understand the best I can

[ABG]

@Makaya_France-Bray

or would I need a separate speed variable as well?

This is from

I’m making a 2D platformer (How do you make a Ball or Sprite 'jump'?)

You can't loop to wait. Here is a relevant project from the defunct Scott Ferguson graphics library: https://groups.google.com/g/app-inventor-developers-library/c/aPctM06_Kuo GravityExercise.aia (4.4 KB) [blocks] (My attempts at flinging with a trackball were mostly futile, but I got a bounce or two out of it.)

Notice how the X and Y are changed separately, under different influences.

[Makaya_France-Bray]

so change that in my updateBallPos procedure? that has the most similar code there

[ABG]

Sure, try it.

You're allowed and encouraged to experiment.