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Is there a good way to apply a force to an object in chipmunk/spacemanager based on that objects rotation or angle (apply it in that direction, automatic)?
I have not found out a way yet since i use ccp(0,200); (cocos positions) to apply the force: [ballSprite applyForce:ccp(0,200)];
How do you do it?
Thanks in advance! (as usual ;D)
You use the rotation to calculate the force on x and y (with sin and cos).
Something like that:
float radians = CC_DEGREES_TO_RADIANS([anObject rotation]);
float _dx = cosf(radians) * somePower;
float _dy = sinf(radians) * somePower;
cpBodyApplyImpulse(aBody, ccp(_dx, _dy), [anObject position]);It's simple enough:
//Get the normalized direction vector
CGPoint dir = ccpForAngle(CC_DEGREES_TO_RADIANS(ballSprite.rotation));
//multiply that by 200 to get a force of 200 in that direction
[ballSprite applyForce:ccpMult(dir, 200)];Depending on how your sprite is oriented, you may have to negate the rotation or add 90 degrees or something....
[Edit:] - By the way, forces are cumulative so you may be wanting to "resetForces" or instead be calling applyImpulse...
@xmawiel - Does it always apply the impulse in the same direction? The code without the +- 90 is designed to launch the ball in whatever direction its rotation is set at. The 90 degrees offset was just in case you drew your spaceship or whatever pointing upwards instead of directly to the right.
xmawiel
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Nice video, hmm so it looks like it's just always launching upwards, perhaps you shouldn't be using the ballSprite's rotation property to get the impulse vector... is there anything else you can use? some information from the slingshot that would give you a better vector? You could even get a good vector by taking the point at the midpoint of the two slingshot prongs and doing this:
CGPoint dir = ccpNormalize(ccpSub(prongMidPt, ballSprite.position));You must log in to post.