fix(memory-shader): 修复调频模糊导致 alpha 变透明并优化移动端采样

Co-authored-by: Cursor <cursoragent@cursor.com>

Assets/Shader/Shader/MemoryTuningSprite.shader

@@ -114,7 +114,9 @@ Shader "AibisDream/MemoryTuningSprite"
             {
                 half pixels = max(1.0, lerp(_PixelMax, _PixelMin, strength));
                 pixels = lerp(pixels, max(1.0, density), step(0.001, density));
-                float2 aspectPixels = float2(pixels, max(1.0, pixels * _MainTex_TexelSize.z / _MainTex_TexelSize.w));
+                float texW = max(1.0, _MainTex_TexelSize.z);
+                float texH = max(1.0, abs(_MainTex_TexelSize.w));
+                float2 aspectPixels = float2(pixels, max(1.0, pixels * texW / texH));
                 return round((uv - 0.5) * aspectPixels) / aspectPixels + 0.5;
             }
 
@@ -130,7 +132,8 @@ Shader "AibisDream/MemoryTuningSprite"
                 return uv + side * wave * volFxStrength * edgeMask;
             }
 
-            half4 BlurSample(float2 uv, half strength)
+            // 仅模糊 RGB；alpha 由调用方取自中心采样，避免图集透明边被混进导致整图变透明（移动端常见）。
+            half3 BlurRgb(float2 uv, half strength)
             {
                 float angle = radians(111.0);
                 float radial = distance(uv, 0.5) * 0.0026;
@@ -138,16 +141,22 @@ Shader "AibisDream/MemoryTuningSprite"
                 float2 stepDir = normalize(float2(sin(angle), cos(angle)));
                 float2 stepUv = stepDir * stepSize;
 
-                half4 col = SampleSprite(uv) * 0.18;
-                col += SampleSprite(uv + stepUv * 1.0) * 0.15;
-                col += SampleSprite(uv - stepUv * 1.0) * 0.15;
-                col += SampleSprite(uv + stepUv * 2.0) * 0.12;
-                col += SampleSprite(uv - stepUv * 2.0) * 0.12;
-                col += SampleSprite(uv + stepUv * 3.0) * 0.09;
-                col += SampleSprite(uv - stepUv * 3.0) * 0.09;
-                col += SampleSprite(uv + stepUv * 4.0) * 0.05;
-                col += SampleSprite(uv - stepUv * 4.0) * 0.05;
-                return col;
+#if defined(SHADER_API_MOBILE)
+                half3 rgb = SampleSprite(uv).rgb * 0.34;
+                rgb += SampleSprite(uv + stepUv).rgb * 0.33;
+                rgb += SampleSprite(uv - stepUv).rgb * 0.33;
+#else
+                half3 rgb = SampleSprite(uv).rgb * 0.18;
+                rgb += SampleSprite(uv + stepUv).rgb * 0.15;
+                rgb += SampleSprite(uv - stepUv).rgb * 0.15;
+                rgb += SampleSprite(uv + stepUv * 2.0).rgb * 0.12;
+                rgb += SampleSprite(uv - stepUv * 2.0).rgb * 0.12;
+                rgb += SampleSprite(uv + stepUv * 3.0).rgb * 0.09;
+                rgb += SampleSprite(uv - stepUv * 3.0).rgb * 0.09;
+                rgb += SampleSprite(uv + stepUv * 4.0).rgb * 0.05;
+                rgb += SampleSprite(uv - stepUv * 4.0).rgb * 0.05;
+#endif
+                return rgb;
             }
 
             half4 ChromaticSample(float2 uv, half4 source, half strength)
@@ -164,7 +173,9 @@ Shader "AibisDream/MemoryTuningSprite"
                 half3 splitRgb = (colA.rgb + colB.rgb) * 0.5865;
                 half splitAlpha = max(max(colA.a, colB.a), source.a);
                 half4 splitCol = half4(splitRgb, splitAlpha);
-                return lerp(source, splitCol, 0.85 * response);
+                half4 result = lerp(source, splitCol, 0.85 * response);
+                result.a = source.a;
+                return result;
             }
 
             half4 frag(Varyings input) : SV_Target
@@ -187,9 +198,12 @@ Shader "AibisDream/MemoryTuningSprite"
                 float2 pixelUv = PixelSnap(uv, pixelate, _PixelatePixelDensity);
                 uv = lerp(uv, pixelUv, pixelate);
 
-                half4 col = lerp(SampleSprite(uv), BlurSample(uv, blur), blur);
+                half4 sharp = SampleSprite(uv);
+                half3 rgb = lerp(sharp.rgb, BlurRgb(uv, blur), blur);
+                half4 col = half4(rgb, sharp.a);
                 col = ChromaticSample(uv, col, clarity);
-                col *= input.color;
+                col.a *= input.color.a;
+                col.rgb *= input.color.rgb;
                 return col;
             }
             ENDHLSL