31 lines
753 B
Go
31 lines
753 B
Go
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package artist
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import "math"
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import "image/color"
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// Dotted is a pattern that produces a grid of circles.
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type Dotted struct {
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Background Pattern
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Foreground Pattern
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Size int
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Spacing int
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}
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// AtWhen satisfies the Pattern interface.
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func (pattern Dotted) AtWhen (x, y, width, height int) (c color.RGBA) {
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xm := x % pattern.Spacing
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ym := y % pattern.Spacing
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if xm < 0 { xm += pattern.Spacing }
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if ym < 0 { xm += pattern.Spacing }
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radius := float64(pattern.Size) / 2
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spacing := float64(pattern.Spacing) / 2 - 0.5
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xf := float64(xm) - spacing
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yf := float64(ym) - spacing
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if math.Sqrt(xf * xf + yf * yf) > radius {
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return pattern.Background.AtWhen(x, y, width, height)
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} else {
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return pattern.Foreground.AtWhen(x, y, width, height)
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}
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}
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