feat(blend): add Greater blend mode

android/app/src/main/java/io/github/artcraftandroid/procraft/ui/Icons.kt

@@ -89,6 +89,7 @@ object PcIcons {
             "Linear Burn" to ours("blend-linear-burn", 26f, "M14.35 6.44L14.27 6.49L12.12 10.46L12.03 10.64L11.91 11.02L11.85 11.41L11.84 11.61L11.87 12L11.96 12.39L12.03 12.57L12.21 12.93L12.32 13.09L12.58 13.4L12.88 13.65L13.22 13.86L13.4 13.94L13.78 14.07L14.17 14.13L14.37 14.14L14.57 14.13L14.96 14.07L15.34 13.94L15.52 13.86L15.86 13.65L16.16 13.4L16.42 13.09L16.62 12.76L16.71 12.57L16.83 12.2L16.89 11.81L16.9 11.61L16.89 11.41L16.83 11.02L16.78 10.82L16.62 10.46L14.47 6.49L14.42 6.45ZM14.39 10.4L14.47 10.45L15.25 12.04L15.33 12.26L15.36 12.49L15.35 12.64L15.28 12.87L15.17 13.07L15.07 13.19L14.95 13.29L14.75 13.4L14.6 13.45L14.37 13.48L14.22 13.46L13.99 13.4L13.79 13.29L13.67 13.19L13.57 13.07L13.46 12.87L13.41 12.72L13.38 12.49L13.41 12.26L13.49 12.04L14.27 10.45L14.32 10.41ZM18.69 16.23L18.84 16.13L18.95 16L19.01 15.89L19.04 15.78L19.04 15.6L18.99 15.43L18.93 15.33L18.85 15.24L18.71 15.13L18.54 15.08L18.42 15.07L18.3 15.09L14.37 15.99L10.44 15.09L10.32 15.07L10.2 15.08L10.09 15.11L9.93 15.2L9.81 15.33L9.73 15.48L9.7 15.6L9.7 15.78L9.76 15.95L9.86 16.09L9.95 16.17L10.11 16.25L11.67 16.61L10.16 16.96L10 17.02L9.86 17.13L9.76 17.28L9.7 17.45L9.7 17.62L9.73 17.74L9.78 17.85L9.84 17.94L9.93 18.03L10.03 18.09L10.14 18.13L10.26 18.15L10.38 18.15L14.37 17.23L18.3 18.14L18.42 18.15L18.54 18.14L18.71 18.09L18.85 17.99L18.93 17.9L19.01 17.74L19.04 17.62L19.04 17.45L18.98 17.28L18.88 17.13L18.79 17.05L18.63 16.97L17.07 16.61Z"),
             "Darker Color" to ours("blend-darker-color", 26f, "M21.73 6.38L21.63 6.03L21.45 5.7L21.21 5.41L20.92 5.17L20.59 4.99L20.24 4.89L19.87 4.85L7.67 4.85L7.3 4.89L6.95 4.99L6.62 5.17L6.33 5.41L6.09 5.7L5.91 6.03L5.81 6.38L5.77 6.75L5.77 18.95L5.81 19.32L5.91 19.67L6.09 20L6.33 20.29L6.62 20.53L6.95 20.71L7.3 20.81L7.67 20.85L19.87 20.85L20.24 20.81L20.59 20.71L20.92 20.53L21.21 20.29L21.45 20L21.63 19.67L21.73 19.32L21.77 18.95L21.77 6.75ZM8.77 11.94L8.57 11.67L8.46 11.36L8.44 11.14L8.46 10.91L8.57 10.6L8.77 10.33L8.94 10.19L9.14 10.08L9.47 10L9.69 10L9.91 10.04L10.12 10.13L10.39 10.33L13.77 13.71L17.15 10.33L17.42 10.13L17.63 10.04L17.96 9.99L18.29 10.04L18.5 10.13L18.77 10.33L18.91 10.5L19.05 10.8L19.1 11.02L19.1 11.25L19.05 11.47L18.91 11.77L18.77 11.94L14.58 16.13L14.4 16.28L14.21 16.38L13.88 16.46L13.66 16.46L13.44 16.42L13.23 16.33L13.04 16.21Z"),
             "Normal" to ours("blend-normal", 26f, "M21.92 12.8L21.88 12.01L21.76 11.22L21.57 10.45L21.3 9.7L20.96 8.98L20.55 8.3L20.08 7.66L19.55 7.07L18.96 6.54L18.32 6.07L17.64 5.66L16.92 5.32L16.17 5.05L15.4 4.86L14.61 4.74L13.82 4.7L13.03 4.74L12.24 4.86L11.47 5.05L10.72 5.32L10 5.66L9.32 6.07L8.68 6.54L8.09 7.07L7.56 7.66L7.09 8.3L6.68 8.98L6.34 9.7L6.07 10.45L5.88 11.22L5.76 12.01L5.72 12.8L5.76 13.59L5.88 14.38L6.07 15.15L6.34 15.9L6.68 16.62L7.09 17.3L7.56 17.94L8.09 18.53L8.68 19.06L9.32 19.53L10 19.94L10.72 20.28L11.47 20.55L12.24 20.74L13.03 20.86L13.82 20.9L14.61 20.86L15.4 20.74L16.17 20.55L16.92 20.28L17.64 19.94L18.32 19.53L18.96 19.06L19.55 18.53L20.08 17.94L20.55 17.3L20.96 16.62L21.3 15.9L21.57 15.15L21.76 14.38L21.88 13.59Z"),
+            "Greater" to ours("blend-greater", 26f, "M12.1 7.02L11.53 6.99L10.96 7.02L10.4 7.1L9.84 7.24L9.31 7.43L8.79 7.68L8.3 7.97L7.84 8.31L7.42 8.69L7.04 9.11L6.7 9.57L6.41 10.06L6.16 10.58L5.97 11.11L5.83 11.67L5.75 12.23L5.72 12.8L5.75 13.37L5.83 13.93L5.97 14.49L6.16 15.02L6.41 15.54L6.7 16.03L7.04 16.49L7.42 16.91L7.84 17.29L8.3 17.63L8.79 17.92L9.31 18.17L9.84 18.36L10.4 18.5L10.96 18.58L11.53 18.61L12.1 18.58L12.66 18.5L13.12 18.39L12.6 18.08L12.24 17.82L11.92 17.55L11.38 17.02L10.71 16.94L10.3 16.84L9.91 16.7L9.54 16.53L9.18 16.31L8.85 16.07L8.54 15.79L8.26 15.48L8.02 15.15L7.8 14.79L7.63 14.42L7.49 14.03L7.39 13.62L7.33 13.21L7.3 12.8L7.33 12.39L7.39 11.98L7.49 11.57L7.63 11.18L7.8 10.81L8.02 10.45L8.26 10.12L8.54 9.81L8.85 9.53L9.18 9.29L9.54 9.07L9.91 8.9L10.3 8.76L10.71 8.66L11.38 8.58L11.92 8.05L12.24 7.78L12.6 7.52L13.12 7.21L12.66 7.1ZM21.92 12.8L21.87 12.04L21.72 11.3L21.61 10.93L21.32 10.23L21.14 9.89L20.72 9.26L20.22 8.69L19.94 8.43L19.34 7.97L19.01 7.77L18.68 7.59L17.98 7.3L17.61 7.19L16.87 7.04L16.11 6.99L15.73 7L15.35 7.04L14.61 7.19L13.89 7.43L13.54 7.59L12.88 7.97L12.57 8.19L12 8.69L11.74 8.97L11.5 9.26L11.08 9.89L10.74 10.58L10.61 10.93L10.41 11.67L10.35 12.04L10.3 12.8L10.31 13.18L10.35 13.56L10.5 14.3L10.74 15.02L10.9 15.37L11.28 16.03L11.5 16.34L12 16.91L12.28 17.17L12.88 17.63L13.2 17.83L13.54 18.01L14.24 18.3L14.61 18.41L15.35 18.56L15.73 18.6L16.49 18.6L17.24 18.5L17.61 18.41L17.98 18.3L18.68 18.01L19.01 17.83L19.65 17.41L19.94 17.17L20.48 16.63L20.94 16.03L21.14 15.71L21.48 15.02L21.61 14.67L21.72 14.3L21.87 13.56Z"),
             "Lighten" to ours("blend-lighten", 26f, "M14.89 3.81L14.76 3.53L14.55 3.3L14.28 3.13L13.97 3.06L13.66 3.07L13.37 3.18L13.11 3.37L12.98 3.53L12.88 3.71L12.82 3.91L12.8 4.12L12.8 6.44L12.82 6.65L12.88 6.85L13.04 7.12L13.19 7.27L13.46 7.43L13.66 7.49L13.87 7.51L14.08 7.49L14.28 7.43L14.46 7.33L14.63 7.2L14.76 7.03L14.86 6.85L14.92 6.65L14.94 6.44L14.94 4.12ZM20.99 7.18L21.1 6.89L21.11 6.58L21.04 6.27L20.94 6.09L20.8 5.92L20.55 5.74L20.26 5.63L19.94 5.62L19.64 5.69L19.45 5.79L19.29 5.92L17.65 7.56L17.52 7.73L17.42 7.91L17.34 8.21L17.34 8.42L17.42 8.73L17.52 8.91L17.65 9.08L17.81 9.21L18 9.31L18.2 9.37L18.41 9.39L18.62 9.37L18.82 9.31L19 9.21L19.16 9.08L20.8 7.44ZM8.2 5.74L7.9 5.63L7.59 5.62L7.28 5.69L7.01 5.85L6.87 6L6.75 6.18L6.64 6.47L6.63 6.79L6.7 7.09L6.8 7.27L6.94 7.44L8.58 9.08L8.74 9.21L8.92 9.31L9.23 9.38L9.44 9.38L9.74 9.31L9.93 9.21L10.09 9.08L10.22 8.91L10.32 8.73L10.38 8.53L10.4 8.32L10.38 8.11L10.32 7.91L10.22 7.73L10.09 7.56L8.45 5.92ZM4.82 11.83L4.54 11.97L4.31 12.18L4.15 12.45L4.07 12.75L4.09 13.07L4.19 13.36L4.38 13.61L4.54 13.75L4.73 13.85L4.93 13.91L5.13 13.93L7.45 13.93L7.66 13.91L7.86 13.85L8.13 13.68L8.34 13.45L8.44 13.27L8.5 13.07L8.52 12.86L8.5 12.65L8.44 12.45L8.34 12.26L8.21 12.1L8.05 11.97L7.86 11.87L7.66 11.81L7.45 11.79L5.13 11.79ZM17.79 11.67L17.66 11.29L17.49 10.92L17.28 10.58L17.04 10.26L16.77 9.96L16.47 9.69L16.15 9.45L15.8 9.24L15.44 9.07L15.06 8.93L14.67 8.84L14.27 8.78L13.87 8.76L13.47 8.78L13.07 8.84L12.68 8.93L12.3 9.07L11.94 9.24L11.59 9.45L11.27 9.69L10.97 9.96L10.7 10.26L10.46 10.58L10.25 10.92L10.08 11.29L9.95 11.67L9.85 12.06L9.79 12.46L9.77 12.86L9.79 13.26L9.85 13.66L9.95 14.05L10.08 14.43L10.25 14.79L10.46 15.14L10.7 15.46L10.97 15.76L11.27 16.03L11.59 16.27L11.94 16.47L12.3 16.65L12.68 16.78L13.07 16.88L13.47 16.94L13.87 16.96L14.27 16.94L14.67 16.88L15.06 16.78L15.44 16.65L15.8 16.47L16.15 16.27L16.47 16.03L16.77 15.76L17.04 15.46L17.28 15.14L17.49 14.79L17.66 14.43L17.79 14.05L17.89 13.66L17.95 13.26L17.97 12.86L17.95 12.46L17.89 12.06ZM22.92 13.88L23.2 13.75L23.43 13.54L23.59 13.27L23.67 12.96L23.67 12.75L23.63 12.55L23.49 12.26L23.28 12.03L23.01 11.87L22.81 11.81L22.61 11.79L20.29 11.79L20.08 11.81L19.88 11.87L19.61 12.03L19.4 12.26L19.3 12.45L19.24 12.65L19.22 12.86L19.24 13.07L19.3 13.27L19.4 13.45L19.53 13.61L19.69 13.75L19.88 13.85L20.08 13.91L20.29 13.93L22.61 13.93ZM6.75 18.53L6.64 18.83L6.63 19.14L6.7 19.44L6.87 19.71L7.1 19.92L7.38 20.06L7.59 20.1L7.8 20.1L8.1 20.02L8.29 19.92L8.45 19.79L10.09 18.15L10.22 17.99L10.32 17.8L10.4 17.5L10.4 17.29L10.32 16.99L10.22 16.8L10.09 16.64L9.93 16.51L9.74 16.41L9.54 16.35L9.33 16.33L9.12 16.35L8.92 16.41L8.74 16.51L8.58 16.64L6.94 18.28ZM19.64 20.02L19.94 20.1L20.26 20.08L20.55 19.98L20.8 19.79L20.99 19.54L21.1 19.24L21.11 18.93L21.04 18.63L20.94 18.44L20.8 18.28L19.16 16.64L19 16.51L18.72 16.37L18.51 16.33L18.3 16.33L18 16.41L17.81 16.51L17.65 16.64L17.52 16.8L17.42 16.99L17.36 17.19L17.34 17.4L17.36 17.6L17.42 17.8L17.52 17.99L17.65 18.15L19.29 19.79L19.45 19.92ZM12.88 22L13.04 22.27L13.28 22.48L13.56 22.62L13.87 22.66L14.18 22.62L14.46 22.48L14.7 22.27L14.86 22L14.92 21.8L14.94 21.59L14.94 19.28L14.92 19.07L14.86 18.87L14.7 18.6L14.46 18.39L14.28 18.29L14.08 18.23L13.87 18.21L13.66 18.23L13.46 18.29L13.28 18.39L13.11 18.52L12.98 18.68L12.88 18.87L12.82 19.07L12.8 19.28L12.8 21.59L12.82 21.8Z"),
             "Screen" to ours("blend-screen", 26f, "M14.82 5.08L14.69 4.92L14.52 4.78L14.34 4.68L14.13 4.62L13.92 4.6L13.71 4.62L13.5 4.68L13.32 4.78L13.15 4.92L13.02 5.08L12.92 5.27L12.86 5.47L12.83 5.69L12.86 5.9L12.92 6.1L13.02 6.29L13.15 6.45L13.32 6.59L13.5 6.69L13.71 6.75L13.92 6.77L14.13 6.75L14.34 6.69L14.52 6.59L14.69 6.45L14.82 6.29L14.92 6.1L14.98 5.9L15.01 5.69L14.98 5.47L14.92 5.27ZM19.78 7.14L19.65 6.97L19.48 6.84L19.3 6.74L19.09 6.68L18.88 6.65L18.67 6.68L18.46 6.74L18.28 6.84L18.11 6.97L17.98 7.14L17.88 7.32L17.82 7.53L17.79 7.74L17.82 7.95L17.88 8.16L17.98 8.34L18.11 8.51L18.28 8.64L18.46 8.74L18.67 8.8L18.88 8.83L19.09 8.8L19.3 8.74L19.48 8.64L19.65 8.51L19.78 8.34L19.88 8.16L19.94 7.95L19.97 7.74L19.94 7.53L19.88 7.32ZM9.86 7.14L9.73 6.97L9.56 6.84L9.38 6.74L9.17 6.68L8.96 6.65L8.75 6.68L8.54 6.74L8.36 6.84L8.19 6.97L8.06 7.14L7.96 7.32L7.9 7.53L7.87 7.74L7.9 7.95L7.96 8.16L8.06 8.34L8.19 8.51L8.36 8.64L8.54 8.74L8.75 8.8L8.96 8.83L9.17 8.8L9.38 8.74L9.56 8.64L9.73 8.51L9.86 8.34L9.96 8.16L10.02 7.95L10.05 7.74L10.02 7.53L9.96 7.32ZM17.89 12.18L17.79 11.66L17.62 11.17L17.51 10.93L17.25 10.47L16.93 10.06L16.75 9.87L16.36 9.52L16.15 9.37L15.69 9.11L15.45 9L14.96 8.83L14.7 8.77L14.18 8.7L13.92 8.69L13.66 8.7L13.14 8.77L12.88 8.83L12.39 9L11.92 9.23L11.69 9.37L11.48 9.52L11.09 9.87L10.74 10.26L10.59 10.47L10.45 10.7L10.22 11.17L10.05 11.66L9.99 11.92L9.92 12.44L9.91 12.7L9.95 13.22L9.99 13.48L10.12 13.99L10.22 14.23L10.45 14.7L10.59 14.93L10.74 15.14L11.09 15.53L11.48 15.88L11.69 16.03L12.15 16.29L12.39 16.4L12.88 16.57L13.14 16.63L13.4 16.67L13.92 16.71L14.44 16.67L14.7 16.63L14.96 16.57L15.45 16.4L15.92 16.17L16.15 16.03L16.56 15.71L16.75 15.53L16.93 15.34L17.25 14.93L17.39 14.7L17.62 14.23L17.79 13.74L17.85 13.48L17.89 13.22L17.93 12.7ZM21.84 12.1L21.7 11.93L21.54 11.8L21.35 11.7L21.15 11.64L20.93 11.61L20.72 11.64L20.52 11.7L20.33 11.8L20.17 11.93L20.03 12.1L19.93 12.28L19.87 12.49L19.85 12.7L19.87 12.91L19.93 13.12L20.03 13.3L20.17 13.47L20.33 13.6L20.52 13.7L20.72 13.76L20.93 13.79L21.15 13.76L21.35 13.7L21.54 13.6L21.7 13.47L21.84 13.3L21.94 13.12L22 12.91L22.02 12.7L22 12.49L21.94 12.28ZM7.81 12.1L7.67 11.93L7.51 11.8L7.32 11.7L7.12 11.64L6.91 11.61L6.69 11.64L6.49 11.7L6.3 11.8L6.14 11.93L6 12.1L5.9 12.28L5.84 12.49L5.82 12.7L5.84 12.91L5.9 13.12L6 13.3L6.14 13.47L6.3 13.6L6.49 13.7L6.69 13.76L6.91 13.79L7.12 13.76L7.32 13.7L7.51 13.6L7.67 13.47L7.81 13.3L7.91 13.12L7.97 12.91L7.99 12.7L7.97 12.49L7.91 12.28ZM9.86 17.06L9.73 16.89L9.56 16.76L9.38 16.66L9.17 16.6L8.96 16.57L8.75 16.6L8.54 16.66L8.36 16.76L8.19 16.89L8.06 17.06L7.96 17.24L7.9 17.45L7.87 17.66L7.9 17.87L7.96 18.08L8.06 18.26L8.19 18.43L8.36 18.56L8.54 18.66L8.75 18.72L8.96 18.75L9.17 18.72L9.38 18.66L9.56 18.56L9.73 18.43L9.86 18.26L9.96 18.08L10.02 17.87L10.05 17.66L10.02 17.45L9.96 17.24ZM19.65 16.89L19.48 16.76L19.3 16.66L19.09 16.6L18.88 16.57L18.67 16.6L18.46 16.66L18.28 16.76L18.11 16.89L17.98 17.06L17.88 17.24L17.82 17.45L17.79 17.66L17.82 17.87L17.88 18.08L17.98 18.26L18.11 18.43L18.28 18.56L18.46 18.66L18.67 18.72L18.88 18.75L19.09 18.72L19.3 18.66L19.48 18.56L19.65 18.43L19.78 18.26L19.88 18.08L19.94 17.87L19.97 17.66L19.94 17.45L19.88 17.24L19.78 17.06ZM14.69 18.95L14.52 18.81L14.34 18.71L14.13 18.65L13.92 18.63L13.71 18.65L13.5 18.71L13.32 18.81L13.15 18.95L13.02 19.11L12.92 19.3L12.86 19.5L12.83 19.71L12.86 19.93L12.92 20.13L13.02 20.32L13.15 20.48L13.32 20.62L13.5 20.72L13.71 20.78L13.92 20.8L14.13 20.78L14.34 20.72L14.52 20.62L14.69 20.48L14.82 20.32L14.92 20.13L14.98 19.93L15.01 19.71L14.98 19.5L14.92 19.3L14.82 19.11Z"),
             "Color Dodge" to ours("blend-color-dodge", 26f, "M13.72 4.98L12.07 11.04L6.07 12.66L6 12.71L5.98 12.77L6.01 12.85L6.07 12.88L12.07 14.5L13.69 20.5L13.72 20.56L13.8 20.59L13.88 20.56L13.91 20.5L15.53 14.5L21.53 12.88L21.59 12.85L21.62 12.77L21.59 12.69L21.53 12.66L15.53 11.04L13.91 5.04L13.88 4.98L13.8 4.95Z"),

assets/icons/slots.tsv

@@ -213,6 +213,7 @@ blend-color-burn	26	26	7.56	4.8	21.47	20.5
 blend-linear-burn	26	26	9.7	4.85	19.04	19.74
 blend-darker-color	26	26	5.77	4.85	21.77	20.85
 blend-normal	26	26	5.72	4.7	21.92	20.9
+blend-greater	26	26	5.72	4.7	21.92	20.9
 blend-lighten	26	26	4.07	2.81	23.67	22.91
 blend-screen	26	26	5.82	4.6	22.02	20.8
 blend-color-dodge	26	26	5.96	4.95	21.64	20.59

crates/core/src/tests.rs

@@ -774,7 +774,7 @@ fn merge_duplicate_blend_and_locks() {
     assert_eq!(s.layers().len(), 2);
     assert!(s.set_layer_blend(copy, procraft_engine::document::BlendMode::Multiply.id()));
     assert!(!s.set_layer_blend(copy, 999));
-    assert_eq!(crate::layers::blend_modes().len(), 27);
+    assert_eq!(crate::layers::blend_modes().len(), 28);
     assert!(s.merge_down(copy));
     assert_eq!(s.layers().len(), 1);
     // red multiplied by red is still red

crates/engine/src/document.rs

@@ -38,12 +38,13 @@ pub enum BlendMode {
     Saturation,
     Color,
     Luminosity,
+    Greater,
 }
 
 impl BlendMode {
     /// Every mode, in the order the layer panel lists them (grouped: darken, normal, lighten,
     /// contrast, difference, colour).
-    pub const ALL: [BlendMode; 27] = [
+    pub const ALL: [BlendMode; 28] = [
         BlendMode::Multiply,
         BlendMode::Darken,
         BlendMode::Shade,
@@ -71,10 +72,11 @@ impl BlendMode {
         BlendMode::Saturation,
         BlendMode::Color,
         BlendMode::Luminosity,
+        BlendMode::Greater,
     ];
 
     /// The highest of the modes' numbers.
-    pub const MAX_ID: u32 = 26;
+    pub const MAX_ID: u32 = 30;
 
     /// The renderer's number for the mode (stable: shaders switch on it).
     pub fn id(self) -> u32 {
@@ -106,6 +108,7 @@ impl BlendMode {
             BlendMode::Color => 24,
             BlendMode::Luminosity => 25,
             BlendMode::Shade => 26,
+            BlendMode::Greater => 30,
         }
     }
 
@@ -142,6 +145,7 @@ impl BlendMode {
             BlendMode::Saturation => "Saturation",
             BlendMode::Color => "Color",
             BlendMode::Luminosity => "Luminosity",
+            BlendMode::Greater => "Greater",
         }
     }
 }

crates/engine/src/formats.rs

@@ -407,6 +407,8 @@ fn blend_key(mode: BlendMode) -> &'static [u8; 4] {
         BlendMode::Saturation => b"sat ",
         BlendMode::Color => b"colr",
         BlendMode::Luminosity => b"lum ",
+        // procreate has not "greater", "normal" is the nearest
+        BlendMode::Greater => b"norm",
     }
 }
 

crates/engine/src/native.rs

@@ -1629,6 +1629,11 @@ mod tests {
     #[test]
     fn every_blend_mode_has_its_number() {
         for m in BlendMode::ALL {
+            // Procreate has no Greater mode: it saves as Normal
+            if m == BlendMode::Greater {
+                assert_eq!(blend_from(blend_to(m)), BlendMode::Normal);
+                continue;
+            }
             assert_eq!(blend_from(blend_to(m)), m, "{m:?}");
         }
         assert_eq!(

crates/engine/src/studio.rs

@@ -318,8 +318,8 @@ impl Brush {
             // blend modes are kept by number (as the layers' are numbered; a grain's own and behind
             // past them)
             "blend_mode" | "burnt_blend" => {
-                let id = value.round().clamp(0.0, BRUSH_BEHIND as f32);
-                let known = id <= BlendMode::MAX_ID as f32 || id == BRUSH_BEHIND as f32;
+                let id = value.round().clamp(0.0, BlendMode::MAX_ID as f32);
+                let known = BlendMode::from_id(id as u32).is_some() || id == BRUSH_BEHIND as f32;
                 self.extra.insert(key.to_owned(), if known { id } else { 0.0 });
             }
             // the grain's and a dual brush's second's: a layer mode or the grain's own heights

crates/gpu/src/canvas.rs

@@ -286,6 +286,11 @@ impl StrokeStyle {
         }
     }
 
+    fn brush_blend(value: f32) -> u32 {
+        let id = value.round().clamp(0.0, BlendMode::MAX_ID as f32) as u32;
+        if BlendMode::from_id(id).is_some() || id == BRUSH_BEHIND { id } else { 0 }
+    }
+
     /// A stroke drawn with `brush`'s shape, grain and rendering.
     pub fn for_brush(
         brush: &Brush,
@@ -329,10 +334,10 @@ impl StrokeStyle {
             grade: if wet { brush.setting("wet_grade").clamp(-1.0, 1.0) } else { 0.0 },
             blur: if wet { brush.setting("wet_blur").clamp(0.0, 1.0) } else { 0.0 },
             wet_jitter: if wet { brush.setting("wet_jitter").clamp(0.0, 1.0) } else { 0.0 },
-            blend: brush.setting("blend_mode").round().clamp(0.0, BRUSH_BEHIND as f32) as u32,
+            blend: Self::brush_blend(brush.setting("blend_mode")),
             blur_jitter: if wet { brush.setting("wet_blur_jitter").clamp(0.0, 1.0) } else { 0.0 },
             grain_blend: brush.setting("grain_blend").round().clamp(0.0, GRAIN_LINEAR_HEIGHT as f32) as u32,
-            burnt_blend: brush.setting("burnt_blend").round().clamp(0.0, BRUSH_BEHIND as f32) as u32,
+            burnt_blend: Self::brush_blend(brush.setting("burnt_blend")),
             // a brush's rotation turns its grain the other way to the shaders' angle
             // the editors' turn of the image, the whole grain with it (the rotation control is
             // each stamp's own: `Stamp::grain_turn`)

crates/gpu/src/shaders/blend.wgsl

@@ -220,9 +220,40 @@ fn blend(b: vec4<f32>, s: vec4<f32>, mode: u32) -> vec4<f32> {
     if (mode == 29u) {
         return b + s * (1.0 - b.a);
     }
+    if (mode == 30u) {
+      return blend_greater(b, s);
+    }
     let cb = unpremultiply(b);
     let cs = unpremultiply(s);
     let mixed = clamp(blend_rgb(cb, cs, mode), vec3<f32>(0.0), vec3<f32>(1.0));
     let rgb = s.a * (1.0 - b.a) * cs + s.a * b.a * mixed + (1.0 - s.a) * b.rgb;
     return vec4<f32>(rgb, s.a + b.a * (1.0 - s.a));
 }
+
+// Standard Greater/Max Alpha Blend for premultiplied targets
+fn blend_greater(b: vec4<f32>, s: vec4<f32>) -> vec4<f32> {
+    let dA = b.a;
+    let sa = s.a;
+
+    // Early exit if background is fully opaque or source is completely transparent
+    if (dA >= 1.0 || sa <= 0.0) {
+        return b;
+    }
+
+    // Target alpha is determined by the greater of the two layers
+    let target_a = max(dA, sa);
+
+    // Unpremultiply both inputs to operate in straight (unassociated) color space
+    let color_b = select(vec3<f32>(0.0), b.rgb / dA, dA > 0.0);
+    let color_s = select(vec3<f32>(0.0), s.rgb / sa, sa > 0.0);
+
+    // Calculate normalized weight based on relative alpha contribution
+    let total_a = dA + sa;
+    let weight = select(0.5, sa / total_a, total_a > 0.0);
+
+    // Blend in straight RGB space
+    let blended_rgb = mix(color_b, color_s, weight);
+
+    // Re-premultiply by the target alpha for output consistency
+    return vec4<f32>(blended_rgb * target_a, target_a);
+}