What technique/code is needed for contra style aiming?

[MarvinH]

Hello,

Are there any tutorials on doing 2D aiming in the style of Contra/Metal Slug? I’m not sure if this is an animation problem, or a code problem. Any insight would be awesome.

In those games, the aiming is done via the Directional pad. The character aims, and the bullet is instantiated based on the direction that the character is pointed in.

Here’s the effect I want:

1. Player presses up,left,right,right/up, left/up
2. The player character sprite moves in that direction
3. If the player presses the shoot key, the bullet moves in that direction

• How do I limit rotation to a 180 degree radius (either left,right,right/up,left/up)
  -Do I need to break down the character into two parts? (One body part for the aiming, one for the rest of the model that handles animations, collisions, etc)

-If the aiming ‘arm’ is parented to the main body, how would i make it face in the same direction that the player’s body is facing (IE left or right?)

I found a this forum, one of the forum commentaters breaks down the technique, but how do i implement it in code?

Example

Here is an example sprite sheet. The top row is the desired effect?

[robertbu]

Your question is too fuzzy. It potentially involves multiple issues, and you’ve not defined how you are going to do things like change the texture of the character or how you are going to move the character.

For setting the texture you can do:

• Use a Quad and an array of textures
• Use a Quad and a sprite sheet. Manipulate the material offset and scale.
• Use a Quad and a texture atlas and manipulate the uv coordinates of the quad.
• Use Unity’s new Sprite
• Use a third-party tool like NGUI or EZGUI

For movement you can:

• Direct movement through the use of the transform
• Use Rigidbody and 3D physics
• Use Rigidbody and 2D physics
• Use a character controller

---

I’m assuming from your sprite sheet, that you don’t really want the character to rotate, but instead want to change the texture of the character. Here is a bit of code to get you started. Based on the use of ‘Horizontal’ and ‘Vertical’ in the Input manager, it sets the direction. In a new project, ‘Horizontal’ and ‘Vertical’ are setup to use the ASDF and arrow keys. Per you question, it limits the direction. to Right, UpRight, Up, UpLeft, and Left. It reports ‘None’ for other directions or no input. Put it on a game object, hit play, and use the ASDF or Arrow keys:

using UnityEngine;
using System.Collections;

public class Directions: MonoBehaviour {

	enum Facing {Right, UpRight, Up, UpLeft, Left, None};
	
	void Update () {
		Vector3 direction = new Vector3(Input.GetAxis("Horizontal"), Input.GetAxis("Vertical"),0.0f );

		Debug.Log (FindFacing(direction));
	}

	Facing FindFacing(Vector3 direction) {
		if (direction == Vector3.zero)
			return Facing.None;

		float angle = Mathf.Atan2(direction.y, direction.x) * Mathf.Rad2Deg;
		Debug.Log ("Angle: "+angle);
		if (angle < 0.0f)
			angle = 360.0f + angle;
		
		angle += 22.5f;
		
		int i = (int)(angle / 45.0f);
		i = i % 8;

		if (i > 4)
			return Facing.None;

		return (Facing)i;
	}
}