Accelerometer Example « cocos2d for iPhone

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Accelerometer Example

(6 posts) (4 voices)

Started 2 years ago by gametest
Latest reply from pabloruiz55

Tags:

accelerometer

gametest
Member

Hello,

My game is 2D. In my game i want move player tank with Accelerometer. I want to move tank in left,right,up and down directions only. So, i am using acceleration.x and acceleration.y only.

Following is my code to move tank. Now my problem is tank not moves smoothly. Gravity and kfilter are used in Accelerometer but i don't know how to use it.

Pls give me one example to solve this problem.

-(void)accelerometerUIAccelerometer *)accelerometer didAccelerateUIAcceleration *)acceleration
{

        float x = (float)acceleration.x;
        float y = (float)acceleration.y;

       if(y > 0.3) //Left
       {
               playertank.position = cpv(playertank.position.x - 2, playertank.position.y);
       }
       else if(y < -0.3) //Right
       {
                playertank.position = cpv(playertank.position.x + 2, playertank.position.y);
       }
       else if(x > -0.3)//up
       {
                playertank.position = cpv(playertank.position.x, playertank.position.y + 2);
       }
       else if(x < -0.7)//Down
       {
           playertank.position = cpv(playertank.position.x , playertank.position.y - 2);
       }
}

Thanks in advance.

Posted 2 years ago #

Kevin
Member

I'd create a variable to track the tank's direction, then set that variable in the accelerometer method, and move the tank in your game loop rather than moving the tank in the accelerometer call. Here's an example:

- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {

UIAccelerationValue x, y;
x = acceleration.x;
y = acceleration.y;

if (x > -0.3) {
tankDirectionX = 1; // or use an enum
}
else if (x < -0.7) {
tankDirectionX = -1;
}
else {
tankDirectionX = 0;
}
// do a similar check for tankDirectionY
}

Then in your game loop, move the tank based on its direction (and speed), do your bounds checking, collision detection, etc. Hope that helps.

Posted 2 years ago #
gametest
Member

I am moving tank with other function & change direction in accelerometer event.
but still I have problem. tank is not moving smoothly.

Pls help me to solve this problem. It is very important to move tank smoothly.

Posted 2 years ago #
Alchemist
Member

You have two problems:
1) You are manipulating speed directly so you loose smoothness
2) Your speed is too high (1 pixel per frame(?))

You must have speed in float values, and scale it down at some frame rate (say 25 fps).

To have better "handling" you should decrease velocity with some friction factor.

i.e.: Accelerometer accelerates speed to 0.3 pixel/s you add pos by speed in each axis (x and y) and de accelerate with some friction value.

In your refresh method you should reduce your "tank direction" by, say, 0.005 each frame (you must test values adequate to your scale of speed/position).

Posted 2 years ago #
gametest
Member

TThnks for quick reply. but i don't understand what u said. where I supposed to set frame.

I think code for accelerometer is working properly. I test the same thing in different application. It works properly. player tank moves smoothly.
I think the problem is due to memory. I use so many sprites as obstacle in my game.

I read somewhere AtlasSprite uses less memory than Sprite. My game is in cocos 2d v0.7. It has not AtlasSprite Class. I want to convert my application to version 0.8. I downloaded .tar file for that. but i don't know how to include it in my xcode.
I read article of it but i don't understand. I want version 0.7 and 0.8 both.

Can u pls give me how to install version 0.8.

Posted 2 years ago #
pabloruiz55
Member

If you already have your project set up, just replace the cocos2d files with the new ones from 0.8. Backup your project before just in case :P
There maybe somethings that could not work that have benn changed between versions, in my case i only had 1 or 2 deprecated functions that i had to replace.

Posted 2 years ago #

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