#region File Description
//-----------------------------------------------------------------------------
// ParticleSystemSettings.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion

#region Using Statements
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
#endregion

namespace ParticlesSettings
{
    /// <summary>
    /// Used to specify the method of acceleration for a particle system.
    /// </summary>
    public enum AccelerationMode
    {
        /// <summary>
        /// The particle system does not use acceleration.
        /// </summary>
        None,

        /// <summary>
        /// The particle system computes the acceleration by using the
        /// MinAccelerationScale and MaxAccelerationScale values to compute a random
        /// scalar value which is then multiplied by the direction of the particles.
        /// </summary>
        Scalar,

        /// <summary>
        /// The particle system computes the acceleration by using the EndVelocity
        /// value and solving the equation vt = v0 + (a0 * t) for a0. See
        /// ParticleSystem.cs for more details.
        /// </summary>
        EndVelocity,

        /// <summary>
        /// The particle system computes the acceleration by using the
        /// MinAccelerationVector and MaxAccelerationVector values to compute a random
        /// vector value which is used as the acceleration of the particles.
        /// </summary>
        Vector
    }

    /// <summary>
    /// Settings class describes all the tweakable options used
    /// to control the appearance of a particle system. Many of the
    /// settings are marked with an attribute that makes them optional
    /// so that XML files can be simpler if they wish to use the default
    /// values.
    /// </summary>
    public class ParticleSystemSettings
    {
        // Sets the range of particles used for each "effect" when the particle system
        // is used.
        public int MinNumParticles;
        public int MaxNumParticles;

        // Name of the texture used by this particle system.  
        public string TextureFilename = null;

        // MinDirectionAngle and MaxDirectionAngle are used to control the possible
        // directions of motion for the particles. We use degrees instead of radians
        // for the settings to make it easier to construct the XML. The ParticleSystem
        // will convert these to radians as it needs.
        [ContentSerializer(Optional = true)]
        public float MinDirectionAngle = 0;
        [ContentSerializer(Optional = true)]
        public float MaxDirectionAngle = 360;
                
        // MinInitialSpeed and MaxInitialSpeed are used to control the initial speed
        // of the particles.      
        public float MinInitialSpeed;
        public float MaxInitialSpeed;

        // Sets the mode for computing the acceleration of the particles.
        public AccelerationMode AccelerationMode = AccelerationMode.None;

        // Controls how the particle velocity will change over their lifetime. If set
        // to 1, particles will keep going at the same speed as when they were created.
        // If set to 0, particles will come to a complete stop right before they die.
        // Values greater than 1 make the particles speed up over time. This field is
        // used when using the AccelerationMode.EndVelocity mode.
        [ContentSerializer(Optional = true)]
        public float EndVelocity = 1f;

        // Controls the minimum and maximum acceleration for the particle when using the
        // AccelerationMode.Scalar mode.
        [ContentSerializer(Optional = true)]
        public float MinAccelerationScale = 0;
        [ContentSerializer(Optional = true)]
        public float MaxAccelerationScale = 0;

        // Controls the minimum and maximum acceleration for the particle when using the
        // AccelerationMode.Vector mode.
        [ContentSerializer(Optional = true)]
        public Vector2 MinAccelerationVector = Vector2.Zero;
        [ContentSerializer(Optional = true)]
        public Vector2 MaxAccelerationVector = Vector2.Zero;

        // Controls how much particles are influenced by the velocity of the object
        // which created them. AddParticles takes in a Vector2 which is the base velocity
        // for the particles being created. That velocity is first multiplied by this
        // EmitterVelocitySensitivity to determine how much the particles are actually
        // affected by that velocity.
        [ContentSerializer(Optional = true)]
        public float EmitterVelocitySensitivity = 0;

        // Range of values controlling how fast the particles rotate. Again, these
        // values should be in degrees for easier XML authoring.
        [ContentSerializer(Optional = true)]
        public float MinRotationSpeed = 0;
        [ContentSerializer(Optional = true)]
        public float MaxRotationSpeed = 0;
                
        // Range of values controlling how long a particle will last.
        public float MinLifetime;
        public float MaxLifetime;

        // Range of values controlling how big the particles are
        [ContentSerializer(Optional = true)]
        public float MinSize = 1;
        [ContentSerializer(Optional = true)]
        public float MaxSize = 1;
                
        // Controls the gravity applied to the particles. This can pull particles down
        // to simulate gravity, up for effects like smoke, or any other direction.        
        [ContentSerializer(Optional = true)]
        public Vector2 Gravity = Vector2.Zero;

        // Alpha blending settings. Our default gives us a BlendState equivalent to
        // BlendState.AlphaBlend which is suitable for many particle effects.
        [ContentSerializer(Optional = true)]
        public Blend SourceBlend = Blend.One;
        [ContentSerializer(Optional = true)]
        public Blend DestinationBlend = Blend.InverseSourceAlpha;
    }
}