Moving Sprite « cocos2d for iPhone

Moving Sprite

(5 posts) (3 voices)

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Jack Here
Member

I have a sprite I want to move around the screen like in the game geometry-wars. I can rotate my sprite just fine but to move it based on where it is pointing I can not. My problem, I think, lies in this bit of code:

spriteObject.position.x = spriteObject.position.x + speed*cos(move_angle);
spriteObject.position.y = spriteObject.position.y + speed*sin(move_angle);

I keep getting syntax errors, invalid Ivalue error to be exact. How do you set the position on a sprite?

Posted 2 years ago #
Codemattic
Moderator

bc you can only use dot notation on the left side of an assign with object pointers. Try:

[spriteObject setPosition:ccp(
spriteObject.position.x + speed*cos(move_angle),
spriteObject.position.y + speed*sin(move_angle)
)];

Posted 2 years ago #
Jack Here
Member

Well that doesnt give me any errors but, it doesnt move the way i want either. Has to be something else Im doing wrong. Thanks for the help though.

Posted 2 years ago #
Codemattic
Moderator

speed is a float and your move_angle is in radians, right ;)
also, use cosf and sinf instead - although that isnt your problem here.

Posted 2 years ago #
newacct
Member

or equivalently

spriteObject.position = ccp(
spriteObject.position.x + speed*cos(move_angle),
spriteObject.position.y + speed*sin(move_angle)
);

or better,

spriteObject.position = ccpAdd(spriteObject.position, ccpMult(ccpForAngle(move_angle), speed));

Posted 2 years ago #

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