protected override void Draw(CanvasDrawingSession drawingSession
#if WINDOWS_UWP
, CanvasSpriteBatch spriteBatch
#endif
)
{
// 逆向遍历队列，可以让新粒子绘制在旧粒子下方，这样当很多粒子在同一个位置生成时，效果较好
for (int i = ActiveParticles.Count - 1; i >= 0; i--)
{
Particle particle = ActiveParticles[i];
// NormalizedLifeTime 是一个0到1之间的值，用来表示粒子在生命周期中的进度，这个值接近0或接近1时，
// 粒子将会渐隐/渐显，使用它来计算粒子的透明度和缩放
float normalizedLifetime = particle.TimeSinceStart / 4;
if (normalizedLifetime > 1)
{
normalizedLifetime = 1;
}
// We want particles to fade in and fade out, so we'll calculate alpha to be
// (normalizedLifetime) * (1 - normalizedLifetime). This way, when normalizedLifetime
// is 0 or 1, alpha is 0. The maximum value is at normalizedLifetime = .5, and is:
//
// (normalizedLifetime) * (1-normalizedLifetime)
// (.5) * (1-.5)
// .25
//
// Since we want the maximum alpha to be 1, not .25, we'll scale the entire equation by 4.
float alpha = (float)EasingHelper.QuinticEase(Windows.UI.Xaml.Media.Animation.EasingMode.EaseOut, normalizedLifetime);
var x = particle.ScaleX;
var y = particle.ScaleY;
// Make particles grow as they age.
// They'll start at 75% of their size, and increase to 100% once they're finished.
if (isImmersive)
{
alpha *= 0.8f;
x *= 1.2f;
y *= 1.2f;
}
#if WINDOWS_UWP
if (spriteBatch != null)
{
spriteBatch.Draw(smokeSurfaces[particle.Key], particle.Position, new Vector4(1, 1, 1, alpha), bitmapCenter,
particle.Rotation, new Vector2(x, y), CanvasSpriteFlip.None);
}
else
#endif
{
// Compute a transform matrix for this particle.
var transform = Matrix3x2.CreateRotation(particle.Rotation, bitmapCenter) *
Matrix3x2.CreateScale(x, y, bitmapCenter) *
Matrix3x2.CreateTranslation(particle.Position - bitmapCenter);
// Draw the particle.
drawingSession.DrawImage(smokeSurfaces[particle.Key], 0, 0, bitmapBounds, alpha, CanvasImageInterpolation.Linear, new Matrix4x4(transform));
}
}
}
public void Update()
{
if (surfaceLoaded)
{
if (nowFrame < inFrames)
{
var progress = nowFrame / (float)inFrames;
progress = (float)EasingHelper.QuinticEase(Windows.UI.Xaml.Media.Animation.EasingMode.EaseOut, progress);
position.X = (float)(xOffset * (progress - 0.5)) / 2;
position.Y = (float)(yOffset * (progress - 0.5)) / 2;
opcity = 0.8f * progress;
}
nowFrame++;
rotation = 0.000174532922222222f * nowFrame;
}
}
public void update(Vector2 size)
{
if (tempSurface != null && canDraw)
{
scale.X = (float)(size.X / bound.Width > size.Y / bound.Height ? size.X / bound.Width : size.Y / bound.Height);
scale.Y = scale.X;
position = size / 2;
if (isImmersive)
{
nowFrame++;
if (nowFrame <= inFrames)
{
opacity = (float)EasingHelper.QuinticEase(Windows.UI.Xaml.Media.Animation.EasingMode.EaseOut, (double)nowFrame / inFrames);
}
}
else if (nowFrame != 0)
{
nowFrame -= 1;
opacity = (float)EasingHelper.QuinticEase(Windows.UI.Xaml.Media.Animation.EasingMode.EaseOut, (double)nowFrame / inFrames);
if (nowFrame == 0)
{
canDraw = false;
}
}
if (enableBlur)
{
blurFrame++;
if (blurFrame <= inFrames)
{
blur.BlurAmount = blurAmount * (float)EasingHelper.CircleEase(Windows.UI.Xaml.Media.Animation.EasingMode.EaseOut, (double)blurFrame / inFrames);
}
}
else if (blurFrame != 0)
{
blurFrame--;
blur.BlurAmount = blurAmount * (float)EasingHelper.CircleEase(Windows.UI.Xaml.Media.Animation.EasingMode.EaseIn, (double)blurFrame / inFrames);
}
}
}
private double GetElasticFactor(double percent)
{
return(ElasticFactor * (1 - EasingHelper.QuinticEase(EasingMode.EaseOut, percent)));
}
