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.NumContacts)
                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)
                {
                    need_sound = false;

                    // reuse the existing sound source
                    sounds[i].Enabled = true;
                    sounds[i].Gain = MathLib.Saturate(volume);
                    sounds[i].WorldTransform = MathLib.Translate(position);
                    Engine.sound.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.Occlusion = 0;
                s.MinDistance = 10.0f;
                s.MaxDistance = 100.0f;
                s.Gain = MathLib.Saturate(volume);
                s.WorldTransform = 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.SetMaterial("mesh_base", "*");
            object_mesh.WorldTransform = 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.AddContactCallback(contact_callback);

        }

        public override bool 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 true;
        }

        public override bool 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 true;
        }

        public override bool Render()
        {

            return true;
        }

        public override bool Flush()
        {

            return true;
        }
        // end of the main loop

        public override bool Shutdown()
        {

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


            return true;
        }

        public override bool Destroy()
        {

            return true;
        }

        public override bool Save(Stream stream)
        {

            return true;
        }

        public override bool Restore(Stream stream)
        {

            return true;
        }
    }
}