fix: replace CLAMP_TO_EDGE with MIRRORED_REPEAT for ambient texture

CLAMP_TO_EDGE stretched edge pixels when ambient shader UVs exceeded
[0,1] range, creating visible dark rectangles on simple/dark artwork
(e.g. Metallica's black album). MIRRORED_REPEAT seamlessly mirrors
the texture instead. Also removed the hard clamp() in the fragment
shader so the mirrored wrapping actually takes effect.

src/lib/immersive/shaders/ambient.frag

@@ -42,8 +42,8 @@ vec3 sampleLayer(vec2 uv, vec2 offset, float scale, float rotation) {
     vec2 scaledUV = center + (rotatedUV - center) * scale;
     // Apply offset
     scaledUV += offset;
-    // Clamp to valid range
-    scaledUV = clamp(scaledUV, 0.0, 1.0);
+    // Let GL_MIRRORED_REPEAT handle out-of-range UVs seamlessly
+    // (no hard clamp — avoids visible edge rectangles on dark artwork)
     return texture(u_texture, scaledUV).rgb;
 }
 

src/lib/immersive/utils/webgl-utils.ts

@@ -167,9 +167,11 @@ export function createTextureFromImage(
 
   gl.bindTexture(gl.TEXTURE_2D, texture);
 
-  // Set texture parameters for smooth scaling
-  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
-  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
+  // Mirrored repeat: when ambient shader UVs exceed [0,1] range,
+  // the texture mirrors back smoothly instead of stretching edge pixels
+  // (CLAMP_TO_EDGE caused visible dark rectangles on simple/dark artwork)
+  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.MIRRORED_REPEAT);
+  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.MIRRORED_REPEAT);
   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);