46 lines
1.4 KiB
Go
46 lines
1.4 KiB
Go
package artist
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import "image/color"
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// Gradient is a pattern that interpolates between two colors.
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type Gradient struct {
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First Pattern
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Second Pattern
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Orientation
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}
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// AtWhen satisfies the Pattern interface.
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func (pattern Gradient) AtWhen (x, y, width, height int) (c color.RGBA) {
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var position float64
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switch pattern.Orientation {
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case OrientationVertical:
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position = float64(y) / float64(height)
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case OrientationDiagonalRight:
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position = (float64(width - x) / float64(width) +
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float64(y) / float64(height)) / 2
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case OrientationHorizontal:
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position = float64(x) / float64(width)
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case OrientationDiagonalLeft:
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position = (float64(x) / float64(width) +
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float64(y) / float64(height)) / 2
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}
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firstColor := pattern.First.AtWhen(x, y, width, height)
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secondColor := pattern.Second.AtWhen(x, y, width, height)
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return LerpRGBA(firstColor, secondColor, position)
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}
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// Lerp linearally interpolates between two integer values.
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func Lerp (first, second int, fac float64) (n int) {
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return int(float64(first) * (1 - fac) + float64(second) * fac)
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}
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// LerpRGBA linearally interpolates between two color.RGBA values.
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func LerpRGBA (first, second color.RGBA, fac float64) (c color.RGBA) {
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return color.RGBA {
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R: uint8(Lerp(int(first.R), int(second.R), fac)),
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G: uint8(Lerp(int(first.G), int(second.G), fac)),
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B: uint8(Lerp(int(first.G), int(second.B), fac)),
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}
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}
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