34 lines
785 B
Go
34 lines
785 B
Go
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package artist
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import "image/color"
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// Checkered is a pattern that produces a grid of two alternating colors.
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type Checkered struct {
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First Pattern
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Second Pattern
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CellWidth, CellHeight int
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}
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// AtWhen satisfies the Pattern interface.
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func (pattern Checkered) AtWhen (x, y, width, height int) (c color.RGBA) {
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twidth := pattern.CellWidth * 2
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theight := pattern.CellHeight * 2
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x %= twidth
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y %= theight
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if x < 0 { x += twidth }
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if y < 0 { x += theight }
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n := 0
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if x >= pattern.CellWidth { n ++ }
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if y >= pattern.CellHeight { n ++ }
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x %= pattern.CellWidth
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y %= pattern.CellHeight
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if n % 2 == 0 {
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return pattern.First.AtWhen(x, y, pattern.CellWidth, pattern.CellHeight)
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} else {
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return pattern.Second.AtWhen(x, y, pattern.CellWidth, pattern.CellHeight)
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}
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}
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