Rotation Advice Needed

KevinCross

Hi

I'm moving a car along an x axis with swipes and want the car to rotate/tilt the angle you've swiped based on the distance you've swiped. If you've swiped only a little distance from the left side of the car it will tilt a little to the left, and if you swipe quickly for a longer distance the car tilts a lot more to the left. And likewise for right swipes.

I've got the left swipes working and the tilting is working perfectly, but when it tilts right it spins around completely, and probably happens at the end of the interpolate duration of 0.1. I'm using Interpolate to rotate the car and it seems to be treating any angles less than 0 as a complete rotation and spins the car right round rather than moving -5 or -10 degrees from 0.

This is my left angle formula

(10/100)*(( game.Screen.Size.Width /100)*( game.Car X - game.Touch X ))

This is the formula I'm using for right turns

-((10/100)*(( game.Screen.Size.Width /100)*( game.Touch X - game.Car X )))

It does tilt right but quite often it spins around a full 360 degrees until game.Touch X = game.Car X which is when the angle is 0 and the car is facing straight up.

Does anyone have an idea how I can rotate an actor right (minus numbers) using interpolate without it doing complete spins please?

Here's a video of the problem in action

RThurman

@KevinCross -- It good that you have it sorted out and working how you like. I hope you don't mind me sharing some tips and ideas for others who might view this thread.

First, I'd suggest to make any graphics to always point to 0 degrees. In GameSalad that is straight to the right ---->. Then things can rotate based on their true starting point. So, for example, one would make a car graphic to point to the right (0 degrees) before bringing it into an actor (that points to 0 degrees by default.) Then one can manually rotate it to 90 degrees (straight up) in the scene.

Next, its probably best to set up some kind of difference measure and then base the actor's movements based upon the difference between the desired state and its current state. For example, you want to base things off of the difference between the actor's X and the mouse's X. In general the equation would be: difference = mouse.X - actor.X

Then it becomes easier to use some general algorithms for getting things to move. They could look like this:

When mouse down
-- Constrain Attribute: self.difference To: game.Mouse.Position.X-self.Position.X
-- Constrain Attribute: self.Position.X To: self.Position.X +(.075*self.difference )
-- Constrain Attribute: self.Rotation To: 90-(.5*self.difference )

Note: Self.difference is a 'real' attribute. The .075 and the .5 can be adjusted to get the effect you are after. They are dampeners that help 'soften' the movements.

Anyway, I hope these ideas might be useful.

KevinCross

Sorted it! I had rules on the car that if it was flagged as right then Interpolate to the angle and likewise for left, but all I really needed was a constrain attribute on the car, constraining it to the car angle attribute calculated from those two formulas above.

KevinCross

Spoke too soon, it's still flipping flipping >.<

EDIT: It flips when the angle is greater than -1 i.e. -0.4 or -0.7 etc. A bit weird but automatically setting the angle to 0 if it's greater than -1 sorts it. I'm confident it's working how I want it to now.

KevinCross

Thanks for the tips @RThurman. I'll take a copy of my project and will replace my code with yours to see it how feels, and whether or not yours is easy enough to eventually introduce the speed of the car to affect the movement and turning angles.

I'm guessing with your example I'd still need to set up a block for each left and right, as left would be self.Position.X - mouse.Position.X and right would be the reverse sum mouse.Position.X - self.Position.X

I'll give the graphics pointing to the right thing a go too.

RThurman

Here is a quick example.

Also no need to set up left and right rules. It just rotates based upon mouse.X.

KevinCross

Wow that's perfect! Thank you.

In my example I have an invisible actor used as a tracking pad so that it won't follow the mouse in the whole window but you've helped enough to get the best of both worlds.

Thanks for your help!

RThurman

You are welcome. Glad you've found it useful.