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100 Days of VR: Day 9 Setting up a Weapon

Josh Chang

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Welcome back to day 9!

Were you wondering why there was a large gap between today and the last post? Well that’s because I went to participate in the Seattle AR/VR hackaton #6!

The hackathon was 3 days long and it took me 2 days to recover from it! Check out my hackathon postmortem!

With the hackathon over, I’m back to my regularly scheduled daily posting! Yay!

Continuing from where we last left off,

The next thing to do is to attach a weapon to our character and then add the game logic for shooting.

As usual let’s get to it!

Adding our Weapon

In our current state, we just have our character:

We need to add a weapon and from my research, in most games, when a player shoots, it’s not actually from the gun, it’s from the camera’s center view.

Not only that, we don’t actually shoot any projectiles as that can become computationally expensive. Instead, we just fire a Raycast and if we hit, we do some gun animation effect to make it appear that the bullets are coming from the gun.

For larger weapons like rocket launchers we have to create the projectiles, but for a fast shooting weapon like an assault rifle or pistol we can just use a Raycast.

Creating our weapon

The first thing we should do is create our “gun”. I’m sure we can grab a gun asset from the game store, but instead, I’m going to first create a simple cube that’ll represent our weapon. I’m sure later on we can just attach the asset and *most likely* everything will be fine. Probably…

First let’s create a Cube and make it the child of our Main Camera. I’m going to name it Gun. I set the transform to these values:

  • Position: (0.25, -0.5, 1)
  • Scale: (0.25, 0.25, 1)

Make sure to disable/remove the Box Collider that gets created with the Cube. If we have it, our player object will collide with the gun causing unintended consequences.

With our addition, we should have something like this:

 
0*SGrgLsUcGYoRqmzd.png

if we look at our Game tab, we should see something like this:

 
0*VTKvMcH4lzzHnEVf.png

Next, we can add some particle effect or something along the lines of that to give the illusion that we’re firing.

I won’t lie and say I know exactly what I’m doing (I don’t), but for now, I’m going to create a simple Particle system and attach it to the tip of the gun.

My intention is that I’ll play the particle effect when we fire and stop it when we stop.

So the first thing that we need to do is to create a new Particle System and make it the child of Gun.

I did some configuration settings such as changing the Z position to 0.2

And here’s the rest of the configurations:

  • Duration: 1
  • Looping: unchecked
  • Start Lifetime: 0.05
  • Start Speed: 5
  • Start Size: 1
  • Start Color: Yellow
  • Play Awake: unchecked

Here’s what it’ll look like and the settings. It doesn’t look great, but I’m sure if we had a material asset we could make this better.

 
0*pTRPpAqFVbvXxZTh.png

Adding the Shooting Script

Next up, I created the shooting script and attached it to our Main Camera. The script will be called PlayerShootingController.

Here’s what a simple shooting script would look like:

 
using UnityEngine;
public class PlayerShootingController : MonoBehaviour
{
    public float Range = 100;
    private Camera _camera;
    private ParticleSystem _particle;
	void Start () {
	    _camera = Camera.main;
	    _particle = GetComponentInChildren<ParticleSystem>();
	}
	
	void Update () {
        
	    if (Input.GetMouseButton(0))
	    {
            Ray ray = _camera.ScreenPointToRay(Input.mousePosition);
            RaycastHit hit = new RaycastHit();
	        if (Physics.Raycast(ray, out hit, Range))
	        {
	            print("hit " + hit.collider.gameObject);
	            _particle.Play();
            }
	    }
	}
}
 

Nothing in this code is particularly complex. We just created a Ray from wherever our mouse is located at and then if we were to hit something, we would print what we hit and play our particle system.

 
0*N0grjDiX3yjR-iLL.png

We want to do more like create a layer mask for our raycast to collide with (such as the Shootable layer), but that’s for another day.

End of Day 8

That’s it for today! Short? Yeah I know, great right?

To summarize what we accomplished today: we created the beginning of our shooting system.

We added a fake gun that is a child of the camera so that whenever we move our mouse, the gun will stay in front of our camera.

Then we added a particle system that will generate particles whenever we shoot.

In the future, I’d like to go back and figure out how to make the particles look more realistic: probably by using better materials for the particle system, but we’ll figure that out when we get there.

Finally, we created a script that will shoot raycasts to where our mouse is pointing at in the screen. We should really make that the center, but that’s something we can fix tomorrow.

Well, it’s been a long day, I’ll see you all tomorrow!

Original Day 9

Visit the 100 Days of VR main page



2 Comments


Recommended Comments

It's true that guns in most games draw rays to get the impact, although they often cast from the gun for accuracy. To do this in Unity parent a empty where the gun barrel ends and use it's transforms for starting the ray.

You need that empty for the projectile particle and for the muzzle flash also. The mesh for the muzzle flash will look like this:

Spoiler

MuzzleFlashMesh.thumb.jpg.9bd6d581e64e50c9ad205032ab3d51eb.jpg


You will draw a flash fire on the planes. In this image you can see a muzzle flash paused:

Spoiler


latest?cb=20141122031144

call-of-dutywwii-e3-screenshots-01.jpg?i

 

The rules for muzzle flashes is the same for explosions: Keep it bright with a clear color outline. Keep it on screen for as few frames as possible and focus more on the effect than the fire.

As you can see in the above images the flash and explosion look cheap even on the one edited for advertising. This is because you need 16-32 frames to do a proper flash or explosion. Making those 32 sprites at 2048 so they match the world would result in a sprite sheet larger than  4096 by 4096.

So often explosions and muzzle flashes are made from 1024 by 1024 * 16 sprites. Resulting in lower quality than the rest of the game. By focusing more on the recoil of the gun or the effect of the explosion you get better looking game.

 

Keep up the good work.

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Thanks for the insightful comment, I really appreciate it! I'll keep this in mind when I move on to working with a real gun model!

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