libGDX weird sprite rotation error

Newbie & Debugging Questions
#1

I am currently working on a project where the character’s arm is rotated around based on the mouse’s location, using Math.atan2(). My problem is, I want the player to be holding weapons in their hand, and it gets a little weird. I’m using the sprite class for rotated images, so I have to position and then rotate the sprite in question. Currently, this is accomplished by this:

primaryWeaponl.setRotation(aimAngle + 90);
		primaryWeaponl.setPosition(
				playerScreenX + armXDis
						+ (float) Math.sin(Math.toRadians(aimAngle))
						* (characterArm.getHeight()), 
				playerScreenY + armYDis
						- (float) Math.cos(Math.toRadians(aimAngle))
						* characterArm.getHeight());

my issue is that when I position the image, it looks just fine:

http://imageshack.us/a/img541/134/error1f.png

http://imageshack.us/a/img515/186/error2es.png

but when I add in the rotation (the first line):

http://imageshack.us/a/img515/8813/error4w.png

http://imageshack.us/a/img577/6536/error3mo.png

I’m not sure what is causing this, but any help would be great ( sorry for the image shapes, I simply cropped them by hand :-\ ) could it be a problem with the sprite class? I’ve tried setting the origin for rotation, but it doesn’t seem to help.

#2

You’ll need to set the sprite origin to the point you want to rotate around. The origin is relative to the sprite’s position (the bottom left corner).

#3

For some reason, setting the sprite origin is doing nothing for me. I set it to (Sprite.getWidth() - 8, 6) ( the location of the handle) and I’m still having the same issue, in the exact same location.

#4

Be sure you are calling sprite.draw(batch) and not batch.draw(sprite). This is an unfortunate API gotcha (Sprite is-a TextureRegion and should have used composition instead, can’t change it now).

#5

I have been using sprite.draw, I’m really not sure what I’m doing wrong. Would it be helpful if I posted the entire render() loop? in the create() loop it sets the player’s arm’s origin just fine, so I’m not sure what the error here is :confused:

#6

Yes of course.

#7

Here it is:
http://pastebin.java-gaming.org/43eff31693d

#8

Don’t call new in your render method.

You are changing the primaryWeaponl position based on the rotation angle. Just set the position, origin, and rotation, then draw.

I recommend creating a simpler test case where you can experiment more easily. You can use this as a base:
https://code.google.com/p/libgdx/wiki/GettingHelp#Barebones_SpriteBatch

#9

Thanks nate, i’ll just use the bare-bones and then see wht my issue is. Thanks :slight_smile:

EDIT: decided to go the easy route since this has been bugging me for the past few days, and it looks nicer than it ever could the other way.