#version 450

// Tonemap pass：HDR（+bloom）→ 显示空间，兼调试视图路由上屏。
// 这是显示变换的显式建模（对齐 UE/Unity：HDR SceneColor → tonemapper → UI）。
// ACES = Narkowicz 拟合（线性域映射到 [0,1]），可经 push constant 关闭
// 退回纯 gamma（旧观感）。
//
// 调试视图：pc.debugView 整型路由到已绑定的中间目标（绑定超集静态成立，
// 运行时零重绑）。HDR 域资源过同一套 exposure/tonemap 保证观感可比；
// LDR 类（velocity/深度）直接可视化。

layout(location = 0) in vec2 fragUV;
layout(location = 0) out vec4 outColor;

layout(set = 0, binding = 0) uniform sampler2D taaImage;         // TAA 后 HDR（主输入）
layout(set = 0, binding = 1) uniform sampler2D bloomImage;
layout(set = 0, binding = 2) uniform sampler2D temporalDiffImage;
layout(set = 0, binding = 3) uniform sampler2D rawHdrImage;      // Forward 直出（TAA 前）
layout(set = 0, binding = 4) uniform sampler2D velocityImage;
layout(set = 0, binding = 5) uniform sampler2D shadowMap0Image;  // D32 深度（r 分量）
layout(set = 0, binding = 6) uniform sampler2D shadowMap1Image;
layout(set = 0, binding = 7) uniform sampler2D shadowMap2Image;
// 环境调试视图源（随环境切换重绑，静态绑定超集）
layout(set = 0, binding = 8) uniform samplerCube envCubeImage;
layout(set = 0, binding = 9) uniform samplerCube irradianceImage;
layout(set = 0, binding = 10) uniform samplerCube prefilterImage;
layout(set = 0, binding = 11) uniform sampler2D brdfLutImage;

// 与 Passes::DebugView 枚举同步（FullscreenGpu.h）
const int VIEW_FINAL        = 0;
const int VIEW_TEMPORALDIFF = 1;
const int VIEW_RAW_HDR      = 2;
const int VIEW_TAA          = 3;
const int VIEW_BLOOM        = 4;
const int VIEW_VELOCITY     = 5;
const int VIEW_SHADOW0      = 6;
const int VIEW_SHADOW1      = 7;
const int VIEW_SHADOW2      = 8;
const int VIEW_ENV_CUBE     = 9;
const int VIEW_IRRADIANCE   = 10;
const int VIEW_PREFILTER    = 11;
const int VIEW_BRDF_LUT     = 12;

// 全屏 pass 通用 push（16B，程序级统一声明，VUID-08878）
layout(push_constant) uniform PushConstants {
    float exposure;      // 曝光系数
    float aces;          // >0.5 启用 ACES 曲线，否则纯 gamma
    float bloomStrength; // bloom 叠加强度（0 = 关闭）
    float debugView;     // 调试视图枚举（整型经 float 传）
} pc;

vec3 acesFilm(vec3 x) {
    return clamp((x * (2.51 * x + 0.03)) / (x * (2.43 * x + 0.59) + 0.14), 0.0, 1.0);
}

vec3 tonemap(vec3 hdr) {
    hdr *= pc.exposure;
    vec3 mapped = (pc.aces > 0.5) ? acesFilm(hdr) : clamp(hdr, 0.0, 1.0);
    return pow(mapped, vec3(1.0 / 2.2));
}

// 深度可视化：反相（近=白，与调试截图风格一致）
vec3 depthView(sampler2D depthImage) {
    float d = texture(depthImage, fragUV).r;
    return vec3(pow(1.0 - d, 2.2));
}

// 全屏 uv → 球面方向（cube 调试视图的经纬展开：横向经度、纵向极角）
vec3 latLongDir(vec2 uv) {
    float phi = (uv.x * 2.0 - 1.0) * 3.14159265358979;     // -π..π 经度
    float theta = (1.0 - uv.y) * 3.14159265358979;         // 0..π 极角（顶=天顶）
    return vec3(sin(theta) * cos(phi), cos(theta), sin(theta) * sin(phi));
}

// cube 视图统一走 tonemap（HDR 域，观感与场景一致）；
// prefilter 纵向映射 mip 链（上锐下糙，直观验证 roughness 分级）
vec3 cubeView(samplerCube cube, float lod) {
    return tonemap(textureLod(cube, latLongDir(fragUV), lod).rgb);
}

void main() {
    int view = int(pc.debugView + 0.5);

    // ---- 调试视图路由 ----
    if (view != VIEW_FINAL) {
        switch (view) {
        case VIEW_TEMPORALDIFF: {
            // 帧历史差异：静止=黑，运动边缘发光
            vec3 d = clamp(texture(temporalDiffImage, fragUV).rgb, 0.0, 1.0);
            outColor = vec4(pow(d, vec3(1.0 / 2.2)), 1.0);
            return;
        }
        case VIEW_RAW_HDR:   outColor = vec4(tonemap(texture(rawHdrImage, fragUV).rgb), 1.0); return;
        case VIEW_TAA:       outColor = vec4(tonemap(texture(taaImage, fragUV).rgb), 1.0); return;
        case VIEW_BLOOM:     outColor = vec4(tonemap(texture(bloomImage, fragUV).rgb * 4.0), 1.0); return;
        case VIEW_VELOCITY: {
            // |velocity| × 增益：静止=黑，运动越快越亮
            vec2 vel = texture(velocityImage, fragUV).xy;
            float mag = clamp(length(vel) * 8.0, 0.0, 1.0);
            outColor = vec4(vec3(mag), 1.0);
            return;
        }
        case VIEW_SHADOW0:   outColor = vec4(depthView(shadowMap0Image), 1.0); return;
        case VIEW_SHADOW1:   outColor = vec4(depthView(shadowMap1Image), 1.0); return;
        case VIEW_SHADOW2:   outColor = vec4(depthView(shadowMap2Image), 1.0); return;
        case VIEW_ENV_CUBE:    outColor = vec4(cubeView(envCubeImage, 0.0), 1.0); return;
        case VIEW_IRRADIANCE:  outColor = vec4(cubeView(irradianceImage, 0.0), 1.0); return;
        case VIEW_PREFILTER:   outColor = vec4(cubeView(prefilterImage, fragUV.y * 4.0), 1.0); return;
        case VIEW_BRDF_LUT: {
            // LUT 是 (F 缩放, F 偏置) 双通道，R/G 直读可视化
            vec2 ab = texture(brdfLutImage, fragUV).rg;
            outColor = vec4(ab, 0.0, 1.0);
            return;
        }
        }
    }

    // ---- 正常路径：TAA 后 HDR + bloom 叠加 → tonemap ----
    vec4 hdrTex = texture(taaImage, fragUV);
    vec3 hdr = hdrTex.rgb + texture(bloomImage, fragUV).rgb * pc.bloomStrength;

    outColor = vec4(tonemap(hdr) * hdrTex.a, hdrTex.a);
}