/**
 * Slightly adapted from https://github.com/mrdoob/three.js
 * MIT License Copyright (c) 2010-2020 three.js authors
 *
 * WebGL port of Subpixel Morphological Antialiasing (SMAA) v2.8
 * Preset: SMAA 1x Medium (with color edge detection)
 * https://github.com/iryoku/smaa/releases/tag/v2.8
 */
export declare const edges_frag = "\nprecision highp float;\nprecision highp int;\nprecision highp sampler2D;\n\nuniform sampler2D tColor;\nuniform vec2 uTexSizeInv;\n\nvarying vec2 vUv;\nvarying vec4 vOffset[3];\n\nvec4 SMAAColorEdgeDetectionPS(vec2 texcoord, vec4 offset[3], sampler2D colorTex) {\n    vec2 threshold = vec2(dEdgeThreshold, dEdgeThreshold);\n\n    // Calculate color deltas:\n    vec4 delta;\n    vec3 C = texture2D(colorTex, texcoord).rgb;\n\n    vec3 Cleft = texture2D(colorTex, offset[0].xy).rgb;\n    vec3 t = abs(C - Cleft);\n    delta.x = max(max(t.r, t.g), t.b);\n\n    vec3 Ctop = texture2D(colorTex, offset[0].zw).rgb;\n    t = abs(C - Ctop);\n    delta.y = max(max(t.r, t.g), t.b);\n\n    // We do the usual threshold:\n    vec2 edges = step(threshold, delta.xy);\n\n    // Then discard if there is no edge:\n    if (dot(edges, vec2(1.0, 1.0 )) == 0.0)\n        discard;\n\n    // Calculate right and bottom deltas:\n    vec3 Cright = texture2D(colorTex, offset[1].xy).rgb;\n    t = abs( C - Cright );\n    delta.z = max(max(t.r, t.g), t.b);\n\n    vec3 Cbottom  = texture2D(colorTex, offset[1].zw).rgb;\n    t = abs(C - Cbottom);\n    delta.w = max(max(t.r, t.g), t.b);\n\n    // Calculate the maximum delta in the direct neighborhood:\n    float maxDelta = max(max(max(delta.x, delta.y), delta.z), delta.w );\n\n    // Calculate left-left and top-top deltas:\n    vec3 Cleftleft  = texture2D(colorTex, offset[2].xy).rgb;\n    t = abs( C - Cleftleft );\n    delta.z = max(max(t.r, t.g), t.b);\n\n    vec3 Ctoptop = texture2D(colorTex, offset[2].zw).rgb;\n    t = abs(C - Ctoptop);\n    delta.w = max(max(t.r, t.g), t.b);\n\n    // Calculate the final maximum delta:\n    maxDelta = max(max(maxDelta, delta.z), delta.w);\n\n    // Local contrast adaptation in action:\n    edges.xy *= step(0.5 * maxDelta, delta.xy);\n\n    return vec4(edges, 0.0, 0.0);\n}\n\nvoid main() {\n    gl_FragColor = SMAAColorEdgeDetectionPS(vUv, vOffset, tColor);\n}\n";