Playing Sounds on Collisions

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Unigine;

#if UNIGINE_DOUBLE
using Vec3 = Unigine.dvec3;
using Vec4 = Unigine.dvec4;
using Mat4 = Unigine.dmat4;
#else
    using Vec3 = Unigine.vec3;
    using Vec4 = Unigine.vec4;
    using Mat4 = Unigine.mat4;
#endif

namespace UnigineApp
{
	class AppWorldLogic : WorldLogic
	{
		// World logic, it takes effect only when the world is loaded.
		// These methods are called right after corresponding world script's (UnigineScript) methods.

        public struct ContactArguments
	    {
           public Body body;
           public int num;

           public ContactArguments(Body body, int num)
		    {
			    this.body = body;
			    this.num = num;
		    }
	    };

        public List<ContactArguments> callbacks = new List<ContactArguments>();
        public List<SoundSource> sounds = new List<SoundSource>();

		public AppWorldLogic()
		{
		}

        public void contact_callback(Body body, int num)
        {
            callbacks.Add(new ContactArguments(body, num));
        }

        public void contact_callback_handler(Body body, int num)
        {

	        if (num >= body.getNumContacts())
		        return;

	        // get coordinates of the contact point
	        Vec3 position = body.getContactPoint(num);
	        // get the relative impulse in the contact point
	        float impulse = body.getContactImpulse(num);
	        // calculate volume of the sound played for the contact
	        float volume = impulse * 0.5f - 1.0f;

	        // a flag indicating that no sounds have played yet
	        bool need_sound = true;
			
	        for (int i = 0; i < sounds.Count; i++)
	        {
		        if (sounds[i].isPlaying() == 0)
		        {
			        need_sound = false;

			        // reuse the existing sound source
			        sounds[i].setEnabled(1);
			        sounds[i].setGain(MathLib.saturate(volume));
			        sounds[i].setWorldTransform(MathLib.translate(position));
					Sound.get().renderWorld(1);
			        sounds[i].play();
			        break;
		        }
	        }
	        if (need_sound)
	        {
		        // create a new sound source
		        SoundSource s = new SoundSource("static_impact_00.wav");
		        // specify necessary settings for the sound source
		        s.setOcclusion(0);
		        s.setMinDistance(10.0f);
		        s.setMaxDistance(100.0f);
                s.setGain(MathLib.saturate(volume));
                s.setWorldTransform(MathLib.translate(position));
		        // play the sound source
		        s.play();

		        // append the sound to the vector of the playing sounds
		        sounds.Add(s);
	        }
        }
		
		// method creating a box mesh with a physical body
        public void create_box(Vec3 position) 
        {

	        Mesh mesh = new Mesh();
	        mesh.addBoxSurface("box_0", new vec3(0.5f));
	        ObjectMeshStatic object_mesh = new ObjectMeshStatic(mesh);
	        object_mesh.release();
	        Editor.get().addNode(object_mesh.getNode());
	        object_mesh.setMaterial("mesh_base", "*");
	        object_mesh.setProperty("surface_base", "*");
	        object_mesh.setWorldTransform(MathLib.translate(position));

	        BodyRigid body = new BodyRigid(object_mesh.getObject());
	        new ShapeBox(body.getBody(), new vec3(0.5f));
			// set a callback function that is run when a contact with the box occurs
	        body.setContactCallback(contact_callback);

        }

		public override int init()
		{

			// create box meshes
			for (int i = -5; i <= 5; i++)
			{
				create_box(new Vec3(0.0f, i * 2.0f, 8.0f + i * 1.0f));
			}
			// create another box mesh
	        create_box(new Vec3(5.0f, 10.0f, 50.0f));

	        sounds.Clear();
	        callbacks.Clear();

			return 1;
		}

		public override int update()
		{
			
            if (callbacks.Count > 0)
	        {
				for (int i = 0; i < callbacks.Count; i++)
				{
					contact_callback_handler(callbacks[i].body, callbacks[i].num);
					callbacks.Remove(callbacks[i]);
				}
				callbacks.Clear();
	        }

			return 1;
		}

		public override int render()
		{

			return 1;
		}

		public override int flush()
		{

			return 1;
		}
		// end of the main loop

		public override int shutdown()
		{

            foreach (var s in sounds)
                s.clearPtr();
            sounds.Clear();


			return 1;
		}

		public override int destroy()
		{

			return 1;
		}

		public override int save(Stream stream)
		{

			return 1;
		}

		public override int restore(Stream stream)
		{

			return 1;
		}
	}
}