72 lines
2.4 KiB
TypeScript
72 lines
2.4 KiB
TypeScript
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/** SkSL：分区上色（保留原图明暗与纹理，按 paintColorMap 叠色） */
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export const REGION_PAINT_SKSL = `
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uniform shader originTex;
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uniform shader paintColorTex;
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uniform shader lowFreqTex;
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uniform shader highFreqTex;
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uniform float colorBaseOpacity;
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uniform float lLightOpacity;
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uniform float textureOpacity;
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uniform float showOrigin;
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float luminance(half3 c) {
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return dot(c, half3(0.2126, 0.7152, 0.0722));
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}
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half3 setLuminance(float lum, half3 base) {
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float diff = lum - luminance(base);
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return base + diff;
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}
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half3 luminosityBlend(half3 base, half3 blend) {
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return setLuminance(luminance(blend), base);
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}
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half3 overlayBlend(half3 base, half3 blend) {
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half3 low = 2.0 * base * blend;
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half3 high = 1.0 - 2.0 * (1.0 - base) * (1.0 - blend);
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return mix(low, high, step(half3(0.5), base));
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}
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half4 main(float2 coord) {
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half4 origin = originTex.eval(coord);
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if (showOrigin > 0.5) {
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return origin;
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}
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half4 paintEntry = paintColorTex.eval(coord);
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// The paintColorMap uses Unpremul alpha: painted pixels → (R,G,B,255),
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// transparent pixels → (0,0,0,0). GPU bilinear sampling interpolates
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// straight-alpha values, so at boundaries rgb = trueColor * sampled.a
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// (contaminated with black from the transparent neighbour).
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//
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// Unpremultiply to recover the true paint color:
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// trueColor = sampled.rgb / sampled.a
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// This eliminates dark fringing at region boundaries.
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float pa = paintEntry.a + 0.0001;
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paintEntry.rgb /= pa;
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// Gate sub-pixel alpha to kill residual sampling noise.
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// Thresholds are deliberately low (≈1.3–3.8 in byte space) because
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// post-unpremul the RGB is correct at any alpha ≥ 0 — we only need
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// to suppress samples that contribute negligibly to the final blend.
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// Using *= preserves the smooth edge; higher-alpha samples pass through.
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paintEntry.a *= smoothstep(0.005, 0.015, paintEntry.a);
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half3 paintRgb = paintEntry.rgb;
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half lowL = lowFreqTex.eval(coord).r;
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half highL = highFreqTex.eval(coord).r;
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half3 base = paintRgb * colorBaseOpacity;
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half3 lit = luminosityBlend(base, half3(lowL));
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half3 withLight = mix(base, lit, lLightOpacity);
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half3 tex = overlayBlend(withLight, half3(highL));
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half3 finalRgb = mix(withLight, tex, textureOpacity);
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// Soft edge blend using the (feathered) alpha from the paint color map as coverage.
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half3 blended = mix(origin.rgb, finalRgb, paintEntry.a);
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return half4(blended, 1.0);
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}
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`;
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