EasyEmitter.cs

namespace Narfox.Utilities
{
    public enum EmitterScale
    {
        Small = 16,
        Medium = 64,
        Large = 256
    }

    public class EasyEmitter : Emitter
    {
        const float DefaultDrag = 3.5f;
        const float VelocityRangePercent = 0.5f;
        const float VelocitySizeCoefficient = 6f;
        const float StartingScaleCoefficient = 0.75f;
        const float ScaleRangePercent = 0.65f;
        const float RotationVelocity = 0.25f;
        const float PiFloat = (float)Math.PI;

        private static readonly Dictionary<EmitterScale, int> ExplosionParticlesPerScale = new Dictionary<EmitterScale, int>
        {
            {EmitterScale.Small, 8},
            {EmitterScale.Medium, 20},
            {EmitterScale.Large, 35}
        };

        private static readonly Dictionary<EmitterScale, int> ContrailParticlesPerScale = new Dictionary<EmitterScale, int>
        {
            {EmitterScale.Small, 2},
            {EmitterScale.Medium, 8},
            {EmitterScale.Large, 12}
        };

        public Color Color
        {
            get
            {
                return color;
            }
            set
            {
                color = value;

                EmissionSettings.Red = color.R / 255f;
                EmissionSettings.Green = color.G / 255f;
                EmissionSettings.Blue = color.B / 255f;
                EmissionSettings.ColorOperation = FlatRedBall.Graphics.ColorOperation.Modulate;
            }
        }

        SpriteList particles { get; set; } = new SpriteList();
        Vector3 lastEmissionPosition;
        EmitterScale emitterScale = EmitterScale.Medium;
        float emissionDistance = 0;
        Color color;

        private EasyEmitter() { }

        private static Vector2 GetTextureScale(AnimationChain particleChain)
        {
            var frame1 = particleChain[0];
            return new Vector2
            {
                X = frame1.Texture.Width * (frame1.RightCoordinate - frame1.LeftCoordinate) / 2f,
                Y = frame1.Texture.Height * (frame1.BottomCoordinate - frame1.TopCoordinate) / 2f
            };
        }

        public static EasyEmitter BuildExplosion(
            AnimationChain particleChain,
            EmitterScale scale = EmitterScale.Medium,
            float lifeSeconds = 1f,
            float wedgeDegrees = 360f,
            float scalePerSecond = 0f,
            float area = 1f)
        {
            var emitter = new EasyEmitter();
            emitter.emitterScale = scale;
            var textureScale = GetTextureScale(particleChain);
            var radialVelocity = (float)scale * VelocitySizeCoefficient * (1 - VelocityRangePercent);
            var radialRange = (float)scale * VelocitySizeCoefficient * VelocityRangePercent;

            emitter.EmissionSettings = new EmissionSettings
            {

                Alpha = 1f,
                AlphaRate = -1f / lifeSeconds,
                AnimationChain = particleChain,
                Animate = true,
                Drag = DefaultDrag,
                ScaleX = textureScale.X * StartingScaleCoefficient,
                ScaleY = textureScale.Y * StartingScaleCoefficient,
                ScaleXRange = textureScale.X * ScaleRangePercent,
                ScaleYRange = textureScale.Y * ScaleRangePercent,
                ScaleXVelocity = scalePerSecond,
                ScaleYVelocity = scalePerSecond,
                RotationZ = -PiFloat,
                RotationZRange = PiFloat * 2f,
                RotationZVelocity = -RotationVelocity,
                RotationZVelocityRange = RotationVelocity * 2f,
                RadialVelocity = radialVelocity,
                RadialVelocityRange = radialRange,
                VelocityRangeType = RangeType.Wedge,
                WedgeAngle = 0,
                WedgeSpread = wedgeDegrees * (PiFloat / 180f)
            };

            emitter.TimedEmission = false;
            emitter.SecondFrequency = 0.1f;
            emitter.RemovalEvent = Emitter.RemovalEventType.Alpha0;
            emitter.AreaEmission = AreaEmissionType.Rectangle;
            emitter.ScaleX = area / 2f;
            emitter.ScaleY = area / 2f;
            emitter.NumberPerEmission = ExplosionParticlesPerScale[scale];

            return emitter;
        }

        public static EasyEmitter BuildContrail(
            AnimationChain particleChain,
            EmitterScale scale = EmitterScale.Medium,
            float distance = 8f,
            float lifeSeconds = 3f,
            float scalePerSecond = 2f,
            float area = 1f)
        {
            var emitter = new EasyEmitter();
            emitter.emitterScale = scale;
            emitter.emissionDistance = distance;
            var textureScale = GetTextureScale(particleChain);
            emitter.EmissionSettings = new EmissionSettings
            {

                Alpha = 1f,
                AlphaRate = -1f / lifeSeconds,
                AnimationChain = particleChain,
                Animate = true,
                Drag = DefaultDrag,
                ScaleY = textureScale.Y * StartingScaleCoefficient,
                ScaleX = textureScale.X * StartingScaleCoefficient,
                ScaleYRange = textureScale.Y * StartingScaleCoefficient * ScaleRangePercent,
                ScaleXRange = textureScale.X * StartingScaleCoefficient * ScaleRangePercent,
                ScaleYVelocity = scalePerSecond,
                ScaleXVelocity = scalePerSecond,
                RotationZ = -PiFloat,
                RotationZRange = PiFloat * 2f,
                RotationZVelocity = -0.5f,
                RotationZVelocityRange = 1f,
                VelocityRangeType = RangeType.Radial
            };

            emitter.TimedEmission = false;
            emitter.RemovalEvent = Emitter.RemovalEventType.Alpha0;
            emitter.AreaEmission = AreaEmissionType.Rectangle;
            emitter.ScaleX = area / 2f;
            emitter.ScaleY = area / 2f;
            emitter.NumberPerEmission = ContrailParticlesPerScale[scale];

            return emitter;
        }

        public new SpriteList Emit()
        {
            particles.Clear();
            Emit(particles);

            return particles;
        }

        public void DistanceEmit()
        {
            var currentPos = Parent?.Position ?? Vector3.Zero;
            var vectorDelta = (currentPos - lastEmissionPosition).Length();
            var elapsedDistance = Math.Abs(vectorDelta);

            if (elapsedDistance >= emissionDistance)
            {
                this.Emit();
                lastEmissionPosition = currentPos;
            }
        }
    }
}