79 lines
1.4 KiB
Go
79 lines
1.4 KiB
Go
package wu
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import (
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"lab.zaar.be/thefish/alchemyst-go/engine/types"
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"math"
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)
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func ipart(x float64) float64 {
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return math.Floor(x)
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}
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func round(x float64) float64 {
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return ipart(x + .5)
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}
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func fpart(x float64) float64 {
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return x - ipart(x)
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}
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func rfpart(x float64) float64 {
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return 1 - fpart(x)
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}
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func (Layer types.Putable) WuLine(x1, y1, x2, y2 float64, w int) {
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dx := x2 - x1
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dy := y2 - y1
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ax := dx
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if ax < 0 {
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ax = -ax
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}
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ay := dy
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if ay < 0 {
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ay = -ay
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}
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var plot func(int, int, float64)
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if ax < ay {
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x1, y1 = y1, x1
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x2, y2 = y2, x2
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dx, dy = dy, dx
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plot = func(x, y int, c float64) {
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Layer.Put(y, x, uint8(255 * c))
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}
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} else {
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plot = func(x, y int, c float64) {
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Layer.Put(x, y, uint8(255 * c))
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}
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}
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if x2 < x1 {
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x1, x2 = x2, x1
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y1, y2 = y2, y1
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}
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gradient := dy / dx
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xend := round(x1)
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yend := y1 + gradient*(xend-x1)
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xgap := rfpart(x1 + .5)
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xpxl1 := int(xend)
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ypxl1 := int(ipart(yend))
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plot(xpxl1, ypxl1, rfpart(yend)*xgap)
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plot(xpxl1, ypxl1+1, fpart(yend)*xgap)
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intery := yend + gradient
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xend = round(x2)
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yend = y2 + gradient*(xend-x2)
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xgap = fpart(x2 + 0.5)
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xpxl2 := int(xend)
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ypxl2 := int(ipart(yend))
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plot(xpxl2, ypxl2, rfpart(yend)*xgap)
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plot(xpxl2, ypxl2+1, fpart(yend)*xgap)
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for x := xpxl1 + 1; x <= xpxl2-1; x++ {
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plot(x, int(ipart(intery)), rfpart(intery))
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plot(x, int(ipart(intery))+1, fpart(intery))
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intery = intery + gradient
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}
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}
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