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osu-lazer/osu.Game/Graphics/ParticleExplosion.cs
2020-11-19 18:46:19 +09:00

145 lines
4.9 KiB
C#

// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
using System;
using System.Collections.Generic;
using osu.Framework.Graphics;
using osu.Framework.Graphics.OpenGL.Vertices;
using osu.Framework.Graphics.Primitives;
using osu.Framework.Graphics.Sprites;
using osu.Framework.Graphics.Textures;
using osu.Framework.Utils;
using osuTK;
namespace osu.Game.Graphics
{
/// <summary>
/// An explosion of textured particles based on how osu-stable randomises the explosion pattern.
/// </summary>
public class ParticleExplosion : Sprite
{
private readonly int particleCount;
private readonly double duration;
private double startTime;
private readonly List<ParticlePart> parts = new List<ParticlePart>();
public ParticleExplosion(Texture texture, int particleCount, double duration)
{
Texture = texture;
this.particleCount = particleCount;
this.duration = duration;
Blending = BlendingParameters.Additive;
}
protected override void LoadComplete()
{
base.LoadComplete();
Restart();
}
/// <summary>
/// Restart the animation from the current point in time.
/// Supports transform time offset chaining.
/// </summary>
public void Restart()
{
startTime = TransformStartTime;
this.FadeOutFromOne(duration);
parts.Clear();
for (int i = 0; i < particleCount; i++)
parts.Add(new ParticlePart(duration));
}
protected override void Update()
{
base.Update();
Invalidate(Invalidation.DrawNode);
}
protected override DrawNode CreateDrawNode() => new ParticleExplosionDrawNode(this);
private class ParticleExplosionDrawNode : SpriteDrawNode
{
private readonly List<ParticlePart> parts = new List<ParticlePart>();
private ParticleExplosion source => (ParticleExplosion)Source;
private double startTime;
private double currentTime;
private Vector2 sourceSize;
public ParticleExplosionDrawNode(Sprite source)
: base(source)
{
}
public override void ApplyState()
{
base.ApplyState();
parts.Clear();
parts.AddRange(source.parts);
sourceSize = source.Size;
startTime = source.startTime;
currentTime = source.Time.Current;
}
protected override void Blit(Action<TexturedVertex2D> vertexAction)
{
var time = currentTime - startTime;
foreach (var p in parts)
{
Vector2 pos = p.PositionAtTime(time);
float alpha = p.AlphaAtTime(time);
var rect = new RectangleF(
pos.X * sourceSize.X - Texture.DisplayWidth / 2,
pos.Y * sourceSize.Y - Texture.DisplayHeight / 2,
Texture.DisplayWidth,
Texture.DisplayHeight);
// convert to screen space.
var quad = new Quad(
Vector2Extensions.Transform(rect.TopLeft, DrawInfo.Matrix),
Vector2Extensions.Transform(rect.TopRight, DrawInfo.Matrix),
Vector2Extensions.Transform(rect.BottomLeft, DrawInfo.Matrix),
Vector2Extensions.Transform(rect.BottomRight, DrawInfo.Matrix)
);
DrawQuad(Texture, quad, DrawColourInfo.Colour.MultiplyAlpha(alpha), null, vertexAction,
new Vector2(InflationAmount.X / DrawRectangle.Width, InflationAmount.Y / DrawRectangle.Height),
null, TextureCoords);
}
}
}
private readonly struct ParticlePart
{
private readonly double duration;
private readonly float direction;
private readonly float distance;
public ParticlePart(double availableDuration)
{
distance = RNG.NextSingle(0.5f);
duration = RNG.NextDouble(availableDuration / 3, availableDuration);
direction = RNG.NextSingle(0, MathF.PI * 2);
}
public float AlphaAtTime(double time) => 1 - progressAtTime(time);
public Vector2 PositionAtTime(double time)
{
var travelledDistance = distance * progressAtTime(time);
return new Vector2(0.5f) + travelledDistance * new Vector2(MathF.Sin(direction), MathF.Cos(direction));
}
private float progressAtTime(double time) => (float)Math.Clamp(time / duration, 0, 1);
}
}
}