/**
 * Shared PBR WGSL functions and light loop code.
 * Concatenated into both shader.ts (standard PBR), terrain-shader.ts (splat PBR),
 * and custom shader codegen.
 */
/** Scene struct definitions shared by PBR, terrain, and custom shaders. */
export declare const SCENE_STRUCTS_WGSL = "\nstruct DirLight {\n  direction: vec4<f32>,\n  color: vec4<f32>,\n};\n\nstruct PointLight {\n  position: vec4<f32>,  // xyz=position, w=range\n  color: vec4<f32>,     // rgb=color, w=intensity\n};\n\nstruct SpotLight {\n  position: vec4<f32>,   // xyz=position, w=range\n  direction: vec4<f32>,  // xyz=direction, w=outerCos\n  color: vec4<f32>,      // rgb=color, w=intensity\n  extra: vec4<f32>,      // x=innerCos\n};\n\nstruct SceneUniforms {\n  cameraPos: vec4<f32>,  // xyz=position, w=time (seconds)\n  numDirLights: u32,\n  numPointLights: u32,\n  numSpotLights: u32,\n  _pad1: u32,\n  dirLights: array<DirLight, 4>,\n  pointLights: array<PointLight, 4>,\n  spotLights: array<SpotLight, 4>,\n  fogEnabled: u32,\n  fogMode: u32,\n  fogDensity: f32,\n  fogStart: f32,\n  fogEnd: f32,\n  cameraNear: f32,\n  cameraFar: f32,\n  _fogPad2: f32,\n  fogColor: vec4<f32>,\n};\n";
/** PBR helper functions: GGX distribution, geometry, Fresnel, computePBR, computeTBN */
export declare const PBR_FUNCTIONS_WGSL = "\n// GGX/Trowbridge-Reitz normal distribution\nfn distributionGGX(N: vec3<f32>, H: vec3<f32>, roughness: f32) -> f32 {\n  let a = roughness * roughness;\n  let a2 = a * a;\n  let NdotH = max(dot(N, H), 0.0);\n  let NdotH2 = NdotH * NdotH;\n  let denom = NdotH2 * (a2 - 1.0) + 1.0;\n  return a2 / (PI * denom * denom);\n}\n\n// Schlick-GGX geometry function\nfn geometrySchlickGGX(NdotV: f32, roughness: f32) -> f32 {\n  let r = roughness + 1.0;\n  let k = (r * r) / 8.0;\n  return NdotV / (NdotV * (1.0 - k) + k);\n}\n\n// Smith's geometry function\nfn geometrySmith(N: vec3<f32>, V: vec3<f32>, L: vec3<f32>, roughness: f32) -> f32 {\n  let NdotV = max(dot(N, V), 0.0);\n  let NdotL = max(dot(N, L), 0.0);\n  return geometrySchlickGGX(NdotV, roughness) * geometrySchlickGGX(NdotL, roughness);\n}\n\n// Fresnel-Schlick approximation\nfn fresnelSchlick(cosTheta: f32, F0: vec3<f32>) -> vec3<f32> {\n  return F0 + (1.0 - F0) * pow(clamp(1.0 - cosTheta, 0.0, 1.0), 5.0);\n}\n\n// Compute PBR contribution from a single light direction\nfn computePBR(\n  N: vec3<f32>, V: vec3<f32>, L: vec3<f32>,\n  albedo: vec3<f32>, metallic: f32, roughness: f32,\n  F0: vec3<f32>, radiance: vec3<f32>,\n) -> vec3<f32> {\n  let H = normalize(V + L);\n  let NDF = distributionGGX(N, H, roughness);\n  let G = geometrySmith(N, V, L, roughness);\n  let F = fresnelSchlick(max(dot(H, V), 0.0), F0);\n\n  let numerator = NDF * G * F;\n  let denominator = 4.0 * max(dot(N, V), 0.0) * max(dot(N, L), 0.0) + 0.0001;\n  let specular = numerator / denominator;\n\n  let kS = F;\n  let kD = (vec3<f32>(1.0) - kS) * (1.0 - metallic);\n  let NdotL = max(dot(N, L), 0.0);\n\n  return (kD * albedo / PI + specular) * radiance * NdotL;\n}\n\n// Compute cotangent-frame TBN from screen-space derivatives\nfn computeTBN(worldPos: vec3<f32>, worldNormal: vec3<f32>, uv: vec2<f32>) -> mat3x3<f32> {\n  let dp1 = dpdx(worldPos);\n  let dp2 = dpdy(worldPos);\n  let duv1 = dpdx(uv);\n  let duv2 = dpdy(uv);\n  let T = normalize(dp1 * duv2.y - dp2 * duv1.y);\n  let B = normalize(dp2 * duv1.x - dp1 * duv2.x);\n  let N = normalize(worldNormal);\n  return mat3x3(T, B, N);\n}\n";
/** Light loop WGSL: iterates dir/point/spot lights with PBR + shadow sampling.
 *  Expects: N, V, albedo, metallic, roughness, F0, worldPosition in scope. Writes to Lo. */
export declare const LIGHT_LOOP_WGSL = "\n  // Directional lights\n  for (var i = 0u; i < scene.numDirLights; i = i + 1u) {\n    let light = scene.dirLights[i];\n    let L = normalize(-light.direction.xyz);\n    let intensity = light.color.w;\n    let radiance = light.color.rgb * intensity;\n    var contribution = computePBR(N, V, L, albedo, metallic, roughness, F0, radiance);\n    let dirSlot = shadow.dirLightToSlot[i];\n    if (dirSlot != 0xFFFFFFFFu) {\n      contribution = contribution * sampleDirShadow(dirSlot, worldPosition, N, length(worldPosition - scene.cameraPos.xyz));\n    }\n    Lo = Lo + contribution;\n  }\n\n  // Point lights\n  for (var i = 0u; i < scene.numPointLights; i = i + 1u) {\n    let light = scene.pointLights[i];\n    let lightPos = light.position.xyz;\n    let range = light.position.w;\n    let intensity = light.color.w;\n\n    let toLight = lightPos - worldPosition;\n    let dist = length(toLight);\n    let L = toLight / max(dist, 0.0001);\n\n    // Smooth distance attenuation with range cutoff\n    let attenuation = max(1.0 - (dist * dist) / (range * range), 0.0);\n    let radiance = light.color.rgb * intensity * attenuation * attenuation;\n\n    var contribution = computePBR(N, V, L, albedo, metallic, roughness, F0, radiance);\n    let pointSlot = shadow.pointLightToSlot[i];\n    if (pointSlot != 0xFFFFFFFFu) {\n      contribution = contribution * samplePointShadow(pointSlot, worldPosition, N);\n    }\n    Lo = Lo + contribution;\n  }\n\n  // Spot lights\n  for (var i = 0u; i < scene.numSpotLights; i = i + 1u) {\n    let light = scene.spotLights[i];\n    let lightPos = light.position.xyz;\n    let range = light.position.w;\n    let spotDir = light.direction.xyz;\n    let outerCos = light.direction.w;\n    let innerCos = light.extra.x;\n    let intensity = light.color.w;\n\n    let toLight = lightPos - worldPosition;\n    let dist = length(toLight);\n    let L = toLight / max(dist, 0.0001);\n\n    // Distance attenuation (same as point light)\n    let distAtt = max(1.0 - (dist * dist) / (range * range), 0.0);\n\n    // Cone attenuation: smoothstep between outer and inner cosines\n    let cosAngle = dot(-L, spotDir);\n    let coneAtt = smoothstep(outerCos, innerCos, cosAngle);\n\n    let attenuation = distAtt * distAtt * coneAtt;\n    let radiance = light.color.rgb * intensity * attenuation;\n\n    var contribution = computePBR(N, V, L, albedo, metallic, roughness, F0, radiance);\n    let spotSlot = shadow.spotLightToSlot[i];\n    if (spotSlot != 0xFFFFFFFFu) {\n      contribution = contribution * sampleSpotShadow(spotSlot, worldPosition, N);\n    }\n    Lo = Lo + contribution;\n  }\n";
/** Fog calculation WGSL. Expects: scene, worldPosition, color in scope. Modifies color. */
export declare const FOG_WGSL = "\n  // Distance fog\n  if (scene.fogEnabled != 0u) {\n    let fogDist = length(scene.cameraPos.xyz - worldPosition);\n    var fogFactor: f32;\n    if (scene.fogMode == 0u) {\n      // Linear\n      fogFactor = saturate((scene.fogEnd - fogDist) / (scene.fogEnd - scene.fogStart));\n    } else {\n      // Exponential\u00B2\n      let d = scene.fogDensity * fogDist;\n      fogFactor = exp(-(d * d));\n    }\n    color = mix(scene.fogColor.rgb, color, fogFactor);\n  }\n";
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