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Use chroma's blends better. #494

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treeform merged 1 commit into from
Aug 4, 2022
Merged

Use chroma's blends better. #494

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124 changes: 5 additions & 119 deletions src/pixie/blends.nim
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Original file line number Diff line number Diff line change
Expand Up @@ -38,25 +38,6 @@ proc alphaFix(backdrop, source, mixed: ColorRGBA): ColorRGBA =
result.b = (b div a div 255).uint8
result.a = a.uint8

proc alphaFix(backdrop, source, mixed: Color): Color =
## After mixing an image, adjust its alpha value to be correct.
result.a = (source.a + backdrop.a * (1.0 - source.a))
if result.a == 0:
return

let
t0 = source.a * (1 - backdrop.a)
t1 = source.a * backdrop.a
t2 = (1 - source.a) * backdrop.a

result.r = t0 * source.r + t1 * mixed.r + t2 * backdrop.r
result.g = t0 * source.g + t1 * mixed.g + t2 * backdrop.g
result.b = t0 * source.b + t1 * mixed.b + t2 * backdrop.b

result.r /= result.a
result.g /= result.a
result.b /= result.a

proc blendAlpha*(backdrop, source: uint8): uint8 {.inline.} =
## Blends alphas of backdrop, source.
source + ((backdrop.uint32 * (255 - source)) div 255).uint8
Expand All @@ -76,65 +57,6 @@ proc hardLight(
else:
screen(backdropColor, sourceColor)

proc softLight(backdrop, source: float32): float32 {.inline.} =
## Pegtop
(1 - 2 * source) * backdrop ^ 2 + 2 * source * backdrop

proc `+`(c: Color, v: float32): Color {.inline.} =
result.r = c.r + v
result.g = c.g + v
result.b = c.b + v
result.a = c.a + v

proc `+`(v: float32, c: Color): Color {.inline.} =
c + v

proc `*`(c: Color, v: float32): Color {.inline.} =
result.r = c.r * v
result.g = c.g * v
result.b = c.b * v
result.a = c.a * v

proc `/`(c: Color, v: float32): Color {.inline.} =
result.r = c.r / v
result.g = c.g / v
result.b = c.b / v
result.a = c.a / v

proc `-`(c: Color, v: float32): Color {.inline.} =
result.r = c.r - v
result.g = c.g - v
result.b = c.b - v
result.a = c.a - v

proc Lum(C: Color): float32 {.inline.} =
0.3 * C.r + 0.59 * C.g + 0.11 * C.b

proc ClipColor(C: var Color) {.inline.} =
let
L = Lum(C)
n = min([C.r, C.g, C.b])
x = max([C.r, C.g, C.b])
if n < 0:
C = L + (((C - L) * L) / (L - n))
if x > 1:
C = L + (((C - L) * (1 - L)) / (x - L))

proc SetLum(C: Color, l: float32): Color {.inline.} =
let d = l - Lum(C)
result.r = C.r + d
result.g = C.g + d
result.b = C.b + d
ClipColor(result)

proc Sat(C: Color): float32 {.inline.} =
max([C.r, C.g, C.b]) - min([C.r, C.g, C.b])

proc SetSat(C: Color, s: float32): Color {.inline.} =
let satC = Sat(C)
if satC > 0:
result = (C - min([C.r, C.g, C.b])) * s / satC

proc blendNormal*(backdrop, source: ColorRGBX): ColorRGBX {.inline.} =
if backdrop.a == 0 or source.a == 255:
return source
Expand Down Expand Up @@ -257,27 +179,7 @@ proc blendOverlay*(backdrop, source: ColorRGBX): ColorRGBX =
result.a = blendAlpha(backdrop.a, source.a)

proc blendSoftLight*(backdrop, source: ColorRGBX): ColorRGBX =
# proc softLight(backdrop, source: int32): uint8 {.inline.} =
# ## Pegtop
# (
# ((255 - 2 * source) * backdrop ^ 2) div 255 ^ 2 +
# (2 * source * backdrop) div 255
# ).uint8

let
backdrop = backdrop.rgba()
source = source.rgba()

let
b = backdrop.color
s = source.color
var blended: Color
blended.r = softLight(b.r, s.r)
blended.g = softLight(b.g, s.g)
blended.b = softLight(b.b, s.b)
blended = alphaFix(b, s, blended)

result = blended.rgbx()
blendSoftLight(backdrop.color, source.color).rgbx

proc blendHardLight*(backdrop, source: ColorRGBX): ColorRGBX =
result.r = hardLight(backdrop.r, backdrop.a, source.r, source.a)
Expand Down Expand Up @@ -311,32 +213,16 @@ proc blendExclusion*(backdrop, source: ColorRGBX): ColorRGBX =
result.a = blendAlpha(backdrop.a, source.a)

proc blendColor*(backdrop, source: ColorRGBX): ColorRGBX =
let
backdrop = backdrop.rgba().color
source = source.rgba().color
blended = SetLum(source, Lum(backdrop))
result = alphaFix(backdrop, source, blended).rgba.rgbx()
blendColor(backdrop.color, source.color).rgbx

proc blendLuminosity*(backdrop, source: ColorRGBX): ColorRGBX =
let
backdrop = backdrop.rgba().color
source = source.rgba().color
blended = SetLum(backdrop, Lum(source))
result = alphaFix(backdrop, source, blended).rgba.rgbx()
blendLuminosity(backdrop.color, source.color).rgbx

proc blendHue*(backdrop, source: ColorRGBX): ColorRGBX =
let
backdrop = backdrop.rgba().color
source = source.rgba().color
blended = SetLum(SetSat(source, Sat(backdrop)), Lum(backdrop))
result = alphaFix(backdrop, source, blended).rgba.rgbx()
blendHue(backdrop.color, source.color).rgbx

proc blendSaturation*(backdrop, source: ColorRGBX): ColorRGBX =
let
backdrop = backdrop.rgba().color
source = source.rgba().color
blended = SetLum(SetSat(backdrop, Sat(source)), Lum(backdrop))
result = alphaFix(backdrop, source, blended).rgba.rgbx()
blendSaturation(backdrop.color, source.color).rgbx

proc blendMask*(backdrop, source: ColorRGBX): ColorRGBX {.inline.} =
let k = source.a.uint32
Expand Down