sanspie
5eb1832907
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34 lines
834 B
Go
34 lines
834 B
Go
package asset
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import (
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"math"
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"sync"
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"aego/gpu"
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"aego/render/texture"
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)
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var particlePuff = sync.OnceValue(func() *texture.Data { return particleMask(false) })
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var particleStreak = sync.OnceValue(func() *texture.Data { return particleMask(true) })
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func particleMask(streak bool) *texture.Data {
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const n = 24
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pixels := make([]byte, n*n*4)
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for y := 0; y < n; y++ {
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for x := 0; x < n; x++ {
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dx, dy := (float64(x)+.5)*2/n-1, (float64(y)+.5)*2/n-1
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if streak {
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dx *= 5.5
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} else {
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dx += .07 * math.Cos(8*dy)
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}
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r := math.Sqrt(dx*dx + dy*dy)
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v := min(max(1-r, 0)*1.5, 1.)
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b := byte(255*v*v*(3-2*v) + .5)
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i := 4 * (n*y + x)
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pixels[i], pixels[i+1], pixels[i+2], pixels[i+3] = b, b, b, b
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}
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}
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return &texture.Data{Width: n, Height: n, Format: gpu.TexRGBA8, Pixels: pixels, Premultiplied: true}
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}
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