pixie/src/pixie/blends.nim
2021-01-29 21:48:52 -06:00

669 lines
23 KiB
Nim

## Blending modes.
import chroma, math, common
when defined(amd64) and not defined(pixieNoSimd):
import nimsimd/sse2
# See https://www.w3.org/TR/compositing-1/
# See https://www.khronos.org/registry/OpenGL/extensions/KHR/KHR_blend_equation_advanced.txt
type
BlendMode* = enum
bmNormal
bmDarken
bmMultiply
bmLinearBurn
bmColorBurn
bmLighten
bmScreen
bmLinearDodge
bmColorDodge
bmOverlay
bmSoftLight
bmHardLight
bmDifference
bmExclusion
bmHue
bmSaturation
bmColor
bmLuminosity
bmMask ## Special blend mode that is used for masking
bmOverwrite ## Special that does not blend but copies the pixels from target.
bmSubtractMask ## Inverse mask
bmIntersectMask
bmExcludeMask
Blender* = proc(a, b: ColorRGBA): ColorRGBA
when defined(release):
{.push checks: off.}
proc min(a, b: uint32): uint32 {.inline.} =
if a < b: a else: b
proc max(a, b: uint32): uint32 {.inline.} =
if a > b: a else: b
proc screenPremultiplied(backdrop, source: uint32): uint8 {.inline.} =
(255 - ((255 - backdrop) * (255 - source)) div 255).uint8
proc hardLightPremultiplied(backdrop, source: uint32): uint8 {.inline.} =
if source <= 127:
((backdrop * 2 * source) div 255).uint8
else:
screenPremultiplied(backdrop, 2 * source - 255)
proc blendAlpha(backdrop, source: uint8): uint8 {.inline.} =
source + ((backdrop.uint32 * (255 - source)) div 255).uint8
proc tripleBlend(result: var ColorRGBA, backdrop, source: ColorRGBA) =
result.a = blendAlpha(backdrop.a, source.a)
if result.a == 0:
result = rgba(0, 0, 0, 0)
else:
let
t0 = (255 - backdrop.a.uint32) * source.a.uint32
t1 = (255 - source.a.uint32) * backdrop.a.uint32
t2 = 255.uint32 * 255
r = t0 * source.r + t1 * backdrop.r + t2 * result.r
g = t0 * source.g + t1 * backdrop.g + t2 * result.g
b = t0 * source.b + t1 * backdrop.b + t2 * result.b
result.r = (r div 255 div result.a).uint8
result.g = (g div 255 div result.a).uint8
result.b = (b div 255 div result.a).uint8
proc blendNormalPremultiplied*(backdrop, source: ColorRGBA): ColorRGBA {.inline.} =
if backdrop.a == 0:
return source
if source.a == 255:
return source
if source.a == 0:
return backdrop
let k = (255 - source.a.uint32)
result.r = source.r + ((backdrop.r.uint32 * k) div 255).uint8
result.g = source.g + ((backdrop.g.uint32 * k) div 255).uint8
result.b = source.b + ((backdrop.b.uint32 * k) div 255).uint8
result.a = blendAlpha(backdrop.a, source.a)
proc blendDarkenPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = min(backdrop.r, source.r)
result.g = min(backdrop.g, source.g)
result.b = min(backdrop.b, source.b)
result.tripleBlend(backdrop, source)
proc blendMultiplyPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = ((backdrop.r.uint32 * source.r) div 255).uint8
result.g = ((backdrop.g.uint32 * source.g) div 255).uint8
result.b = ((backdrop.b.uint32 * source.b) div 255).uint8
result.tripleBlend(backdrop, source)
proc blendLinearBurnPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = min(0, backdrop.r.uint32 + source.r.uint32 - 255).uint8
result.g = min(0, backdrop.g.uint32 + source.g.uint32 - 255).uint8
result.b = min(0, backdrop.b.uint32 + source.b.uint32 - 255).uint8
result.a = blendAlpha(backdrop.a, source.a)
proc blendLightenPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = max(backdrop.r, source.r)
result.g = max(backdrop.g, source.g)
result.b = max(backdrop.b, source.b)
result.a = blendAlpha(backdrop.a, source.a)
proc blendColorBurnPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
proc blend(backdrop, source: uint32): uint8 {.inline.} =
if backdrop == 255:
255.uint8
elif source == 0:
0
else:
255 - min(255, (255 * (255 - backdrop)) div source).uint8
result.r = blend(backdrop.r, source.r)
result.g = blend(backdrop.g, source.g)
result.b = blend(backdrop.b, source.b)
result.tripleBlend(backdrop, source)
proc blendScreenPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = screenPremultiplied(backdrop.r, source.r)
result.g = screenPremultiplied(backdrop.g, source.g)
result.b = screenPremultiplied(backdrop.b, source.b)
result.a = blendAlpha(backdrop.a, source.a)
proc blendLinearDodgePremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = min(backdrop.r.uint32 + source.r, 255).uint8
result.g = min(backdrop.g.uint32 + source.g, 255).uint8
result.b = min(backdrop.b.uint32 + source.b, 255).uint8
result.a = blendAlpha(backdrop.a, source.a)
proc blendColorDodgePremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
proc blend(backdrop, source: uint32): uint8 {.inline.} =
if backdrop == 0:
0.uint8
elif source == 255:
255
else:
min(255, (255 * backdrop) div (255 - source)).uint8
result.r = blend(backdrop.r, source.r)
result.g = blend(backdrop.g, source.g)
result.b = blend(backdrop.b, source.b)
result.a = blendAlpha(backdrop.a, source.a)
proc blendOverlayPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = hardLightPremultiplied(source.r, backdrop.r)
result.g = hardLightPremultiplied(source.g, backdrop.g)
result.b = hardLightPremultiplied(source.b, backdrop.b)
result.a = blendAlpha(backdrop.a, source.a)
proc blendHardLightyPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = hardLightPremultiplied(backdrop.r, source.r)
result.g = hardLightPremultiplied(backdrop.g, source.g)
result.b = hardLightPremultiplied(backdrop.b, source.b)
result.a = blendAlpha(backdrop.a, source.a)
proc blendDifferencePremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
result.r = max(backdrop.r, source.r) - min(backdrop.r, source.r)
result.g = max(backdrop.g, source.g) - min(backdrop.g, source.g)
result.b = max(backdrop.b, source.b) - min(backdrop.b, source.b)
result.a = blendAlpha(backdrop.a, source.a)
proc blendExclusionPremultiplied(backdrop, source: ColorRGBA): ColorRGBA =
proc blend(backdrop, source: uint32): uint8 {.inline.} =
max(0, backdrop + source - (2 * backdrop * source) div 255).uint8
result.r = blend(backdrop.r.uint32, source.r.uint32)
result.g = blend(backdrop.g.uint32, source.g.uint32)
result.b = blend(backdrop.b.uint32, source.b.uint32)
result.a = blendAlpha(backdrop.a, source.a)
when defined(amd64) and not defined(pixieNoSimd):
proc blendNormalPremultiplied*(backdrop, source: M128i): M128i {.inline.} =
let
alphaMask = mm_set1_epi32(cast[int32](0xff000000))
oddMask = mm_set1_epi16(cast[int16](0xff00))
div255 = mm_set1_epi16(cast[int16](0x8081))
# Shortcuts didn't help (backdrop.a == 0, source.a == 0, source.a == 255)
var
sourceAlpha = mm_and_si128(source, alphaMask)
backdropEven = mm_slli_epi16(backdrop, 8)
backdropOdd = mm_and_si128(backdrop, oddMask)
sourceAlpha = mm_or_si128(sourceAlpha, mm_srli_epi32(sourceAlpha, 16))
let k = mm_sub_epi32(
mm_set1_epi32(cast[int32]([0.uint8, 255, 0, 255])),
sourceAlpha
)
backdropEven = mm_mulhi_epu16(backdropEven, k)
backdropOdd = mm_mulhi_epu16(backdropOdd, k)
backdropEven = mm_srli_epi16(mm_mulhi_epu16(backdropEven, div255), 7)
backdropOdd = mm_srli_epi16(mm_mulhi_epu16(backdropOdd, div255), 7)
mm_add_epi8(
source,
mm_or_si128(backdropEven, mm_slli_epi16(backdropOdd, 8))
)
when defined(release):
{.pop.}
proc `+`*(a, b: Color): Color {.inline.} =
result.r = a.r + b.r
result.g = a.g + b.g
result.b = a.b + b.b
result.a = a.a + b.a
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 `*`*(v: float32, target: Color): Color {.inline.} =
target * 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 screen(backdrop, source: float32): float32 {.inline.} =
# 1 - (1 - backdrop) * (1 - source)
# proc hardLight(backdrop, source: float32): float32 {.inline.} =
# if source <= 0.5:
# backdrop * 2 * source
# else:
# screen(backdrop, 2 * source - 1)
proc softLight(backdrop, source: float32): float32 {.inline.} =
## Pegtop
(1 - 2 * source) * backdrop ^ 2 + 2 * source * backdrop
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 alphaFix(backdrop, source, mixed: Color): Color =
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 blendNormalFloats*(backdrop, source: Color): Color {.inline.} =
# result = source
# result = alphaFix(backdrop, source, result)
# proc blendDarkenFloats*(backdrop, source: Color): Color {.inline.} =
# result.r = min(backdrop.r, source.r)
# result.g = min(backdrop.g, source.g)
# result.b = min(backdrop.b, source.b)
# result = alphaFix(backdrop, source, result)
# proc blendMultiplyFloats*(backdrop, source: Color): Color {.inline.} =
# result.r = backdrop.r * source.r
# result.g = backdrop.g * source.g
# result.b = backdrop.b * source.b
# result = alphaFix(backdrop, source, result)
# proc blendLinearBurnFloats*(backdrop, source: Color): Color {.inline.} =
# result.r = backdrop.r + source.r - 1
# result.g = backdrop.g + source.g - 1
# result.b = backdrop.b + source.b - 1
# result = alphaFix(backdrop, source, result)
# proc blendColorBurnFloats*(backdrop, source: Color): Color {.inline.} =
# proc blend(backdrop, source: float32): float32 {.inline.} =
# if backdrop == 1:
# 1.0
# elif source == 0:
# 0.0
# else:
# 1.0 - min(1, (1 - backdrop) / source)
# result.r = blend(backdrop.r, source.r)
# result.g = blend(backdrop.g, source.g)
# result.b = blend(backdrop.b, source.b)
# result = alphaFix(backdrop, source, result)
# proc blendLightenFloats*(backdrop, source: Color): Color {.inline.} =
# result.r = max(backdrop.r, source.r)
# result.g = max(backdrop.g, source.g)
# result.b = max(backdrop.b, source.b)
# result = alphaFix(backdrop, source, result)
# proc blendScreenFloats*(backdrop, source: Color): Color {.inline.} =
# result.r = screen(backdrop.r, source.r)
# result.g = screen(backdrop.g, source.g)
# result.b = screen(backdrop.b, source.b)
# result = alphaFix(backdrop, source, result)
# proc blendLinearDodgeFloats*(backdrop, source: Color): Color {.inline.} =
# result.r = backdrop.r + source.r
# result.g = backdrop.g + source.g
# result.b = backdrop.b + source.b
# result = alphaFix(backdrop, source, result)
# proc blendColorDodgeFloats*(backdrop, source: Color): Color {.inline.} =
# proc blend(backdrop, source: float32): float32 {.inline.} =
# if backdrop == 0:
# 0.0
# elif source == 1:
# 1.0
# else:
# min(1, backdrop / (1 - source))
# result.r = blend(backdrop.r, source.r)
# result.g = blend(backdrop.g, source.g)
# result.b = blend(backdrop.b, source.b)
# result = alphaFix(backdrop, source, result)
# proc blendOverlayFloats*(backdrop, source: Color): Color {.inline.} =
# result.r = hardLight(source.r, backdrop.r)
# result.g = hardLight(source.g, backdrop.g)
# result.b = hardLight(source.b, backdrop.b)
# result = alphaFix(backdrop, source, result)
# proc blendHardLightFloats*(backdrop, source: Color): Color {.inline.} =
# result.r = hardLight(backdrop.r, source.r)
# result.g = hardLight(backdrop.g, source.g)
# result.b = hardLight(backdrop.b, source.b)
# result = alphaFix(backdrop, source, result)
proc blendSoftLightFloats*(backdrop, source: Color): Color {.inline.} =
result.r = softLight(backdrop.r, source.r)
result.g = softLight(backdrop.g, source.g)
result.b = softLight(backdrop.b, source.b)
result = alphaFix(backdrop, source, result)
# proc blendDifferenceFloats*(backdrop, source: Color): Color {.inline.} =
# result.r = abs(backdrop.r - source.r)
# result.g = abs(backdrop.g - source.g)
# result.b = abs(backdrop.b - source.b)
# result = alphaFix(backdrop, source, result)
# proc blendExclusionFloats*(backdrop, source: Color): Color {.inline.} =
# proc blend(backdrop, source: float32): float32 {.inline.} =
# backdrop + source - 2 * backdrop * source
# result.r = blend(backdrop.r, source.r)
# result.g = blend(backdrop.g, source.g)
# result.b = blend(backdrop.b, source.b)
# result = alphaFix(backdrop, source, result)
proc blendColorFloats*(backdrop, source: Color): Color {.inline.} =
result = SetLum(source, Lum(backdrop))
result = alphaFix(backdrop, source, result)
proc blendLuminosityFloats*(backdrop, source: Color): Color {.inline.} =
result = SetLum(backdrop, Lum(source))
result = alphaFix(backdrop, source, result)
proc blendHueFloats*(backdrop, source: Color): Color {.inline.} =
result = SetLum(SetSat(source, Sat(backdrop)), Lum(backdrop))
result = alphaFix(backdrop, source, result)
proc blendSaturationFloats*(backdrop, source: Color): Color {.inline.} =
result = SetLum(SetSat(backdrop, Sat(source)), Lum(backdrop))
result = alphaFix(backdrop, source, result)
# proc blendMaskFloats*(backdrop, source: Color): Color {.inline.} =
# result = backdrop
# result.a = min(backdrop.a, source.a)
# proc blendSubtractMaskFloats*(backdrop, source: Color): Color {.inline.} =
# result = backdrop
# result.a = backdrop.a * (1 - source.a)
# proc blendIntersectMaskFloats*(backdrop, source: Color): Color {.inline.} =
# result = backdrop
# result.a = backdrop.a * source.a
# proc blendExcludeMaskFloats*(backdrop, source: Color): Color {.inline.} =
# result = backdrop
# result.a = abs(backdrop.a - source.a)
# proc blendOverwriteFloats*(backdrop, source: Color): Color {.inline.} =
# source
when defined(amd64) and not defined(pixieNoSimd):
proc alphaFix(backdrop, source: ColorRGBA, vb, vs, vm: M128): ColorRGBA =
let
sa = source.a.float32
ba = backdrop.a.float32
a = sa + ba * (255 - sa) / 255
if a == 0:
return
let
t0 = mm_set1_ps(sa * (255 - ba))
t1 = mm_set1_ps(sa * ba)
t2 = mm_set1_ps((255 - sa) * ba)
va = mm_set1_ps(a)
v255 = mm_set1_ps(255)
values = cast[array[4, uint32]](
mm_cvtps_epi32((t0 * vs + t1 * vm + t2 * vb) / va / v255)
)
result.r = values[0].uint8
result.g = values[1].uint8
result.b = values[2].uint8
result.a = a.uint8
proc alphaFix(backdrop, source, mixed: ColorRGBA): ColorRGBA {.inline.} =
if backdrop.a == 0 and source.a == 0:
return
let
vb = mm_setr_ps(backdrop.r.float32, backdrop.g.float32, backdrop.b.float32, 0)
vs = mm_setr_ps(source.r.float32, source.g.float32, source.b.float32, 0)
vm = mm_setr_ps(mixed.r.float32, mixed.g.float32, mixed.b.float32, 0)
alphaFix(backdrop, source, vb, vs, vm)
else:
proc alphaFix(backdrop, source, mixed: ColorRGBA): ColorRGBA {.inline.} =
let
sa = source.a.uint32
ba = backdrop.a.uint32
t0 = sa * (255 - ba)
t1 = sa * ba
t2 = (255 - sa) * ba
let
r = t0 * source.r.uint32 + t1 * mixed.r.uint32 + t2 * backdrop.r.uint32
g = t0 * source.g.uint32 + t1 * mixed.g.uint32 + t2 * backdrop.g.uint32
b = t0 * source.b.uint32 + t1 * mixed.b.uint32 + t2 * backdrop.b.uint32
a = sa + ba * (255 - sa) div 255
if a == 0:
return
result.r = (r div a div 255).uint8
result.g = (g div a div 255).uint8
result.b = (b div a div 255).uint8
result.a = a.uint8
proc blendNormal(backdrop, source: ColorRGBA): ColorRGBA =
blendNormalPremultiplied(
backdrop.toPremultipliedAlpha(),
source.toPremultipliedAlpha()
).toStraightAlpha()
proc blendDarken(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendDarkenPremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendMultiply(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendMultiplyPremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendLinearBurn(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendLinearBurnPremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendColorBurn(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendColorBurnPremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendLighten(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendLightenPremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendScreen(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendScreenPremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendLinearDodge(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendLinearDodgePremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendColorDodge(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendColorDodgePremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendOverlay(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendOverlayPremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendHardLight(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendHardLightyPremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendSoftLight(backdrop, source: ColorRGBA): ColorRGBA =
when defined(amd64) and not defined(pixieNoSimd):
let
vb = mm_setr_ps(backdrop.r.float32, backdrop.g.float32, backdrop.b.float32, 0)
vs = mm_setr_ps(source.r.float32, source.g.float32, source.b.float32, 0)
v2 = mm_set1_ps(2)
v255 = mm_set1_ps(255)
v255sq = mm_set1_ps(255 * 255)
vm = ((v255 - v2 * vs) * vb * vb) / v255sq + (v2 * vs * vb) / v255
values = cast[array[4, uint32]](mm_cvtps_epi32(vm))
result.r = values[0].uint8
result.g = values[1].uint8
result.b = values[2].uint8
result = alphaFix(backdrop, source, vb, vs, vm)
else:
blendSoftLightFloats(backdrop.color, source.color).rgba
# proc softLight(backdrop, source: int32): uint8 {.inline.} =
# ## Pegtop
# (
# ((255 - 2 * source) * (backdrop ^ 2)) div (255 ^ 2) +
# (2 * source * backdrop) div 255
# ).uint8
# result.r = softLight(backdrop.r.int32, source.r.int32)
# result.g = softLight(backdrop.g.int32, source.g.int32)
# result.b = softLight(backdrop.b.int32, source.b.int32)
# result = alphaFix(backdrop, source, result)
proc blendDifference(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendDifferencePremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendExclusion(backdrop, source: ColorRGBA): ColorRGBA =
let
backdrop = backdrop.toPremultipliedAlpha()
source = source.toPremultipliedAlpha()
result = blendExclusionPremultiplied(backdrop, source)
result = result.toStraightAlpha()
proc blendColor(backdrop, source: ColorRGBA): ColorRGBA =
blendColorFloats(backdrop.color, source.color).rgba
proc blendLuminosity(backdrop, source: ColorRGBA): ColorRGBA =
blendLuminosityFloats(backdrop.color, source.color).rgba
proc blendHue(backdrop, source: ColorRGBA): ColorRGBA =
blendHueFloats(backdrop.color, source.color).rgba
proc blendSaturation(backdrop, source: ColorRGBA): ColorRGBA =
blendSaturationFloats(backdrop.color, source.color).rgba
proc blendMask(backdrop, source: ColorRGBA): ColorRGBA =
result = backdrop
result.a = min(backdrop.a, source.a)
proc blendSubtractMask(backdrop, source: ColorRGBA): ColorRGBA =
result = backdrop
result.a = max(0, (backdrop.a.uint32 * (255 - source.a.uint32)) div 255).uint8
proc blendIntersectMask(backdrop, source: ColorRGBA): ColorRGBA =
result = backdrop
result.a = ((backdrop.a.uint32 * (source.a.uint32)) div 255).uint8
proc blendExcludeMask(backdrop, source: ColorRGBA): ColorRGBA =
result = backdrop
result.a = max(backdrop.a, source.a) - min(backdrop.a, source.a)
proc blendOverwrite(backdrop, source: ColorRGBA): ColorRGBA =
source
proc blender*(blendMode: BlendMode): Blender =
case blendMode
of bmNormal: blendNormal
of bmDarken: blendDarken
of bmMultiply: blendMultiply
of bmLinearBurn: blendLinearBurn
of bmColorBurn: blendColorBurn
of bmLighten: blendLighten
of bmScreen: blendScreen
of bmLinearDodge: blendLinearDodge
of bmColorDodge: blendColorDodge
of bmOverlay: blendOverlay
of bmSoftLight: blendSoftLight
of bmHardLight: blendHardLight
of bmDifference: blendDifference
of bmExclusion: blendExclusion
of bmHue: blendHue
of bmSaturation: blendSaturation
of bmColor: blendColor
of bmLuminosity: blendLuminosity
of bmMask: blendMask
of bmOverwrite: blendOverwrite
of bmSubtractMask: blendSubtractMask
of bmIntersectMask: blendIntersectMask
of bmExcludeMask: blendExcludeMask