diff options
Diffstat (limited to 'gfx/wr/wrench/reftests/blend/difference-transparent-ref.yaml')
| -rw-r--r-- | gfx/wr/wrench/reftests/blend/difference-transparent-ref.yaml | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/gfx/wr/wrench/reftests/blend/difference-transparent-ref.yaml b/gfx/wr/wrench/reftests/blend/difference-transparent-ref.yaml new file mode 100644 index 0000000000..8ed801fb15 --- /dev/null +++ b/gfx/wr/wrench/reftests/blend/difference-transparent-ref.yaml @@ -0,0 +1,23 @@ +--- +root: + items: + - type: rect + bounds: [0, 0, 100, 100] + + # First blend black rect with green in place + # Cs = (1 - αb) x Cs + αb x B(Cb, Cs) + # B(Cb, Cs) = | Cb - Cs | = (0, 0, 0) + # 0.5 * (0, 255, 0) + 0.5 * (0, 0, 0) = (0, 127.5, 0) + # + # Now, composite the resulting color with src-over; the alpha is the original alpha for the top layer + # while the color is the blending result + # co = αs x Fa x Cs + αb x Fb x Cb - this is premultiplied + # αo = αs + αb x (1 – αs) + # Source over: Fa = 1; Fb = 1 – αs + # co = 0.5 * 1 * (0, 127.5, 0) + 0.5 * 0.5 * (0, 255, 0) = (0, 63.5, 0) + 0.25 * (0, 255, 0) = (0, 127.5, 0) + # ao = 0.5 + 0.5 * 0.5 = 0.75 + # Co = co/ao = (0, 127.5, 0) / 0.75 + # + # Now alpha composite on white background + # co = 0.75 * 1 * (0, 127.5, 0) / 0.75 + 1 * 0.25 * (255, 255, 255) = (0, 127.5, 0) + (63.75, 63.75, 63.75) = (63.75, 159, 63.75) = (64, 191, 64) + color: [64, 191, 64] |