155 lines
3.9 KiB
Go
155 lines
3.9 KiB
Go
package compositor
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import (
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"image"
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"math"
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)
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// DrawMetallicSheen 绘制对角金属反光梯度（screen 混合）
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// 复刻 laserBatchExport.js 中 drawMetallicSheen
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func DrawMetallicSheen(dst *image.NRGBA, cfg GratingConfig) {
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cw := dst.Bounds().Dx()
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ch := dst.Bounds().Dy()
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deg := cfg.SheenBandAngle
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if deg == 0 {
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deg = 135
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}
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// 与色带垂直方向
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deg += 90
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rad := deg * math.Pi / 180
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diag := math.Sqrt(float64(cw*cw + ch*ch))
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cx := float64(cw) / 2
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cy := float64(ch) / 2
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x0 := cx - math.Cos(rad)*diag/2
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y0 := cy - math.Sin(rad)*diag/2
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x1 := cx + math.Cos(rad)*diag/2
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y1 := cy + math.Sin(rad)*diag/2
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alpha := 0.22
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for y := 0; y < ch; y++ {
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for x := 0; x < cw; x++ {
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// 计算投影位置 0-1
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t := projectPointOnLine(float64(x), float64(y), x0, y0, x1, y1)
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// 中间带高亮，两端透明
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var brightness float64
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if t > 0.30 && t < 0.70 {
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// 高亮区域：余弦波
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brightness = math.Cos((t-0.50)/0.20*math.Pi) * 0.5
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if brightness < 0 {
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brightness = 0
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}
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}
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if brightness < 0.01 {
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continue
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}
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applyScreenPixel(dst, x, y, 220.0/255.0, 230.0/255.0, 240.0/255.0, brightness*alpha)
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}
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}
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}
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func projectPointOnLine(px, py, lx0, ly0, lx1, ly1 float64) float64 {
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dx := lx1 - lx0
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dy := ly1 - ly0
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lenSq := dx*dx + dy*dy
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if lenSq < 0.001 {
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return 0.5
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}
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t := ((px-lx0)*dx + (py-ly0)*dy) / lenSq
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return clamp01(t)
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}
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// DrawFrostMatte 磨砂哑光层
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// 复刻 laserBatchExport.js 中 drawFrostMatte
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func DrawFrostMatte(dst *image.NRGBA, variantIndex int) {
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cw := dst.Bounds().Dx()
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ch := dst.Bounds().Dy()
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frost := 0.18 // 固定强度
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// 颗粒噪声
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seed := variantIndex*1201 + 77
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n := int(3500 + frost*7500)
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for k := 0; k < n; k++ {
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seed = (seed*9301 + 49297) % 233280
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x := seed % cw
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seed = (seed*9301 + 49297) % 233280
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y := seed % ch
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seed = (seed*9301 + 49297) % 233280
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v := 190 + seed%65
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a := 0.022 + float64(seed%55)/1000.0
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idx := dst.PixOffset(x, y)
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// soft-light 混合简化
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factor := a * (0.35 + frost*0.25)
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dst.Pix[idx] = uint8(clamp01(float64(dst.Pix[idx])/255.0 + float64(v)*factor/255.0) * 255)
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dst.Pix[idx+1] = uint8(clamp01(float64(dst.Pix[idx+1])/255.0 + float64(v)*factor/255.0) * 255)
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dst.Pix[idx+2] = uint8(clamp01(float64(dst.Pix[idx+2])/255.0 + float64(v+6)*factor/255.0) * 255)
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}
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}
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// DrawFilmGrain 胶片颗粒
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// 复刻 laserBatchExport.js 中 drawFilmGrain
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func DrawFilmGrain(dst *image.NRGBA, variantIndex int) {
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cw := dst.Bounds().Dx()
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ch := dst.Bounds().Dy()
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maxDots := 8
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seed := variantIndex*313 + 17
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for i := 0; i < maxDots; i++ {
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seed = (seed*1103515245 + 12345) & 0x7fffffff
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fx := float64(seed) / float64(0x7fffffff) * float64(cw)
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seed = (seed*1103515245 + 12345) & 0x7fffffff
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fy := float64(seed) / float64(0x7fffffff) * float64(ch)
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x := int(fx)
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y := int(fy)
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if x < 0 || x >= cw || y < 0 || y >= ch {
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continue
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}
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seed = (seed*1103515245 + 12345) & 0x7fffffff
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radius := float64(seed)/float64(0x7fffffff)*1.5 + 0.3
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alpha := 0.08 + float64(seed%12)/100.0
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drawSoftDot(dst, x, y, int(radius), alpha)
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}
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}
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func drawSoftDot(dst *image.NRGBA, cx, cy, radius int, alpha float64) {
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for dy := -radius; dy <= radius; dy++ {
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for dx := -radius; dx <= radius; dx++ {
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if dx*dx+dy*dy > radius*radius {
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continue
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}
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px, py := cx+dx, cy+dy
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if px < 0 || px >= dst.Bounds().Dx() || py < 0 || py >= dst.Bounds().Dy() {
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continue
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}
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dist := math.Sqrt(float64(dx*dx + dy*dy))
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fade := 1 - dist/float64(radius)
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idx := dst.PixOffset(px, py)
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sc := alpha * fade
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dst.Pix[idx] = uint8(clamp01(float64(dst.Pix[idx])/255.0 + 1.0*sc) * 255)
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dst.Pix[idx+1] = uint8(clamp01(float64(dst.Pix[idx+1])/255.0 + 1.0*sc) * 255)
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dst.Pix[idx+2] = uint8(clamp01(float64(dst.Pix[idx+2])/255.0 + 1.0*sc) * 255)
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}
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}
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}
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// DrawGratingFinish 光栅 finish：颗粒 + 磨砂
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func DrawGratingFinish(dst *image.NRGBA, variantIndex int) {
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DrawFilmGrain(dst, variantIndex)
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DrawFrostMatte(dst, variantIndex)
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}
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