/**
 * BoxShadow SDF 쉐이더
 * Rectangle(0.0)과 Ellipse(1.0) 모두를 지원합니다.
 */
export declare const shadowVertex = "\n  attribute vec2 position;\n  attribute vec2 uv;\n  uniform mat4 uModelMatrix;\n  uniform mat4 uViewMatrix;\n  uniform mat4 uProjectionMatrix;\n  varying vec2 vUV;\n\n  void main() {\n    vUV = uv;\n    gl_Position = uProjectionMatrix * uViewMatrix * uModelMatrix * vec4(position, 0.0, 1.0);\n  }\n";
export declare const shadowFragment = "\n  precision highp float;\n  uniform vec4 uColor;\n  uniform float uOpacity;\n  uniform vec2 uSize;      // Quad size (includes blur padding)\n  uniform vec2 uBoxSize;   // Actual object size (w, h)\n  uniform vec2 uOffset;    // [offsetX, offsetY]\n  uniform float uBlur;\n  uniform float uSpread;\n  uniform float uIsEllipse;\n  uniform vec4 uBorderRadius; // [TR, BR, TL, BL]\n  varying vec2 vUV;\n\n  float sdRoundedBox(vec2 p, vec2 b, vec4 r) {\n    r.xy = (p.x > 0.0) ? r.xy : r.zw;\n    r.x  = (p.y > 0.0) ? r.x  : r.y;\n    vec2 q = abs(p) - b + r.x;\n    return min(max(q.x, q.y), 0.0) + length(max(q, 0.0)) - r.x;\n  }\n\n  void main() {\n    // p is pixel mapped: center of the object is (0,0)\n    vec2 p = (vUV - 0.5) * uSize;\n    \n    // Shadow center is offset from the object center\n    // We negate uOffset.y because WebGL UV +y is typically UP, whereas CSS offset +y is DOWN.\n    vec2 shadowP = p - vec2(uOffset.x, -uOffset.y);\n    \n    float d = 0.0;\n    float innerMask = 0.0;\n    vec2 radius = uBoxSize * 0.5;\n\n    if (uIsEllipse > 0.5) {\n      if (radius.x <= 0.0 || radius.y <= 0.0) {\n         discard;\n      }\n      vec2 scaledShadowP = shadowP / radius;\n      d = (length(scaledShadowP) - 1.0) * min(radius.x, radius.y);\n      \n      vec2 scaledInnerP = p / radius;\n      innerMask = (length(scaledInnerP) - 1.0) * min(radius.x, radius.y);\n    } else {\n      d = sdRoundedBox(shadowP, radius, uBorderRadius);\n      innerMask = sdRoundedBox(p, radius, uBorderRadius);\n    }\n\n    // Apply shadow spread\n    d -= uSpread;\n\n    float alpha = 1.0;\n    if (uBlur > 0.0) {\n      alpha = 1.0 - smoothstep(-uBlur, uBlur, d);\n    } else {\n      alpha = step(d, 0.0);\n    }\n\n    // Discard pixels that are INSIDE the actual box! (Hollow out the center)\n    if (innerMask <= 0.0) discard;\n\n    if (alpha <= 0.0) discard;\n\n    float finalAlpha = uColor.a * uOpacity * alpha;\n    gl_FragColor = vec4(uColor.rgb * finalAlpha, finalAlpha);\n  }\n";