#version 450

// Bloom 高斯模糊：可分离 9-tap，方向由 push 给出（H/V 各跑一次）。
// 源图为半分辨率，线性采样 + 权重对应的偏移天然抗锯齿。

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

layout(set = 0, binding = 0) uniform sampler2D srcImage;

layout(push_constant) uniform PushConstants {
    float exposure;   // 未用（程序级统一布局）
    float stepX;      // param0: UV 步长 x（水平 pass = 1/width，垂直 = 0）
    float stepY;      // param1: UV 步长 y
    float _pad0;
} pc;

const float weights[5] = float[](0.227027, 0.1945946, 0.1216216, 0.054054, 0.016216);

void main() {
    vec2 off = vec2(pc.stepX, pc.stepY);

    vec3 c = texture(srcImage, fragUV).rgb * weights[0];
    for (int i = 1; i < 5; ++i) {
        c += texture(srcImage, fragUV + off * float(i)).rgb * weights[i];
        c += texture(srcImage, fragUV - off * float(i)).rgb * weights[i];
    }
    outColor = vec4(c, 1.0);
}