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3 replies to this topic

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#1
Members - Reputation: **108**

Posted 07 August 2012 - 11:53 AM

I was trying to figure out how to make a sprite always look at the players current position. My problem is I am not sure how to check which way the sprite is facing in relation to the players position and adjust him accordingly. I would be grateful if I could get any suggestions as to how to start approaching this.

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#4
Members - Reputation: **585**

Posted 07 August 2012 - 02:32 PM

I'll assume you are using c# and XNA. You should use Math.atan2(x2-x1,y2-y1) instead of atan(dx/dy) so you don't have to worry about special case dy=0 and don't have to find wich side the target is. Also what I like to use in cases like these I like to use the following code.

This should always turn to the direction that is closer to the target. Deadzone is the amount of radians(you get radians from degrees with degrees/360*(2*PI)) the seeker can be off course before it starts to correct its course and should always be between 0 and PI radians(0 and 180 degrees) for this to work correctly.

If there are any errors in the code or elsewhere I blame the late hours.

targetangle=Math.Atan2(target.x-this.x,target.y-this.y)//get the angle to the target turnangle=targetangle-currentangle;//get the difference between the current angle and the target angle if(turnangle>2*Math.PI)//make sure to wrap the angle between 0 and 2PI turnangle-=2*Math.PI if(turnangle<0) turnagnel+=2*Math.PI if(turnangle<Math.PI&&turnangle>Deadzone){//Check wich side you should turn to get to your target. turnright(); } else if(turnangle>Math.PI&&turnangle<(2*Math.PI)-Deadzone) { turnleft(); }

This should always turn to the direction that is closer to the target. Deadzone is the amount of radians(you get radians from degrees with degrees/360*(2*PI)) the seeker can be off course before it starts to correct its course and should always be between 0 and PI radians(0 and 180 degrees) for this to work correctly.

If there are any errors in the code or elsewhere I blame the late hours.

**Edited by PunCrathod, 07 August 2012 - 02:45 PM.**