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tomo-old/artist/circlebordered.go
2023-01-24 15:35:00 -05:00

34 lines
829 B
Go

package artist
import "math"
import "image/color"
// EllipticallyBordered is a pattern with a border and a fill that is elliptical
// in shape.
type EllipticallyBordered struct {
Fill Pattern
Stroke
}
// AtWhen satisfies the Pattern interface.
func (pattern EllipticallyBordered) AtWhen (x, y, width, height int) (c color.RGBA) {
xf := (float64(x) + 0.5) / float64(width ) * 2 - 1
yf := (float64(y) + 0.5) / float64(height) * 2 - 1
distance := math.Sqrt(xf * xf + yf * yf)
var radius float64
if width < height {
// vertical
radius = 1 - float64(pattern.Weight * 2) / float64(width)
} else {
// horizontal
radius = 1 - float64(pattern.Weight * 2) / float64(height)
}
if distance < radius {
return pattern.Fill.AtWhen(x, y, width, height)
} else {
return pattern.Stroke.AtWhen(x, y, width, height)
}
}