koobas.hobune.stream
shoot cannon in the direction barrel is facing
I am teaching myself unity 3d 4.3 so i can create 2D game. As a practice i am writing scorched earth. It is 2D and I rotate the gun barrel, around Z-axis. Lets say it is pointing to right, up 45 degree. Now I created a bullet as child of the barrel. I have code
GameObject newBullet = (GameObject)Instantiate(originalBullet, originalBullet.transform.position, originalBullet.transform.rotation);
newBullet.rigidbody2D.AddForce(new Vector2(1,1) * 250);
Original bullet is placed right in front of the barrel and i clone it. I am having problem with AddForce. Vector2(1,1) is hardcoded to 45 world-degree, but how do I get the direction of the barrel in relation to the world?
Also, is there a good example i can look at it for writing tank shooting game?
Thanks
You should look at the barrel's transform to know it's direction. Depending on how you setup the barrel object it can be either transform.forward, transform.up or transform.right
If you need a Vector2 type then code should look something like:
Vector2 vBarrelDir = new Vector2(transform.up.x,transform.up.y);
newBullet.rigidbody2D.AddForce(vBarrelDir * 250f);
thanks that did it. I still don't understand why it works. per doc, transform.up is green axis, which in my case Y-axis. why is getting .x and .y of y-axis give the direction i want? I believe the better question is, how do i tell which direction the barrel is facing? Is it usually z direction? in that case, shouldn't i have used transform.forward?
Yes, transform.forward would make more sense - but you have to realize unity can't really tell which direction is "forward" on any given mesh ... it's just a fancy name for the object's Z-Axis.
It really depends how your local coordinates are setup in the mesh. When you select your barrel object, you can see it's local coordinate system with the 3 colored arrows as the principal axes of that coordinate system.
If you are the one who made the model (in 3DS-$$anonymous$$ax/$$anonymous$$aya/Blender) you can easily rotate the object so it aligns with the Z-Axis. But it really is not required. There may be some unity scripts that can do that as well ...
