shader_type canvas_item;

uniform sampler2D screen_texture : hint_screen_texture, repeat_disable, filter_nearest;

// 效果控制参数
uniform float fisheye_strength : hint_range(0.0, 2.0) = 1.0;
uniform float curve_strength : hint_range(0.0, 2.0) = 1.0;
uniform float chromatic_aberration : hint_range(0.0, 0.01) = 0.002;
uniform float scanline_intensity : hint_range(0.0, 1.0) = 0.35;
uniform float scanline_speed : hint_range(0.0, 10.0) = 3.5;
uniform float vignette_intensity : hint_range(0.0, 1.0) = 0.3;
uniform float brightness : hint_range(0.5, 10.0) = 5.0;
uniform float distortion_amount : hint_range(0.0, 0.02) = 0.0017;
uniform vec3 color_shift = vec3(0.95, 1.05, 0.95);

// 优化后的鱼眼效果
vec2 apply_fisheye(vec2 uv) {
    vec2 centered = uv - 0.5;
    float dist = length(centered);

    // 避免除零和优化计算
    if (dist < 0.001) return uv;

    // 使用更高效的鱼眼公式
    float factor = 1.0 + (fisheye_strength - 1.0) * dist * dist;
    return 0.5 + centered * factor;
}

// 优化后的CRT曲线效果
vec2 apply_crt_curve(vec2 uv) {
    vec2 centered = (uv - 0.5) * 2.0;
    centered *= 1.1 * curve_strength;

    // 简化的曲线计算
    vec2 curve_factor;
    curve_factor.x = 1.0 + pow(abs(centered.y) * 0.2, 2.0);
    curve_factor.y = 1.0 + pow(abs(centered.x) * 0.25, 2.0);

    centered *= curve_factor;
    centered = centered * 0.5 + 0.5;

    // 边界调整
    return centered * 0.92 + 0.04;
}

// 优化的色差效果
vec3 sample_with_chromatic_aberration(sampler2D tex, vec2 uv, float offset) {
    vec3 color;
    color.r = texture(tex, uv + vec2(offset, 0.0)).r;
    color.g = texture(tex, uv).g;
    color.b = texture(tex, uv - vec2(offset, 0.0)).b;
    return color;
}

void fragment() {
    vec2 screen_uv = SCREEN_UV;

    // 应用畸变效果
    vec2 distorted_uv = apply_fisheye(screen_uv);
    distorted_uv = apply_crt_curve(distorted_uv);

    // 边界检查（提前返回以节省计算）
    if (distorted_uv.x < 0.0 || distorted_uv.x > 1.0 ||
        distorted_uv.y < 0.0 || distorted_uv.y > 1.0) {
        COLOR = vec4(0.0, 0.0, 0.0, 1.0);
    }
	else{
	    // 计算扭曲偏移
	    float time_factor = TIME * 0.3;
	    float distortion = sin(time_factor + distorted_uv.y * 21.0) *
	                      sin(TIME * 0.7 + distorted_uv.y * 29.0) *
	                      sin(0.3 + TIME * 0.33 + distorted_uv.y * 31.0) *
	                      distortion_amount;

	    // 采样并应用色差
	    vec2 sample_uv = distorted_uv + vec2(distortion, 0.0);
	    vec3 color = sample_with_chromatic_aberration(screen_texture, sample_uv, chromatic_aberration);

	    // 添加辉光效果（简化版）
	    vec3 glow = sample_with_chromatic_aberration(screen_texture, sample_uv * 0.75, chromatic_aberration * 1.5);
	    color += glow * 0.07;

	    // 色彩调整
	    color = clamp(color * 0.6 + 0.4 * color * color, 0.0, 1.0);

	    // 晕影效果
	    vec2 vignette_coord = distorted_uv * (1.0 - distorted_uv);
	    float vignette = pow(vignette_coord.x * vignette_coord.y * 16.0, vignette_intensity);
	    color *= vignette;

	    // 扫描线效果
	    float scanline = sin(distorted_uv.y * 1.0 / SCREEN_PIXEL_SIZE.y * 1.5 + TIME * scanline_speed);
	    scanline = clamp(scanline_intensity + scanline_intensity * scanline, 0.0, 1.0);
	    color *= 0.4 + 0.7 * pow(scanline, 1.7);

	    // 颜色偏移和亮度调整
	    color *= color_shift * brightness;

	    // CRT像素网格效果
	    float pixel_mask = 1.0 - 0.65 * step(0.5, mod(FRAGCOORD.x, 2.0));
	    color *= pixel_mask;

	    // 轻微的闪烁效果
	    color *= 1.0 + 0.01 * sin(TIME * 110.0);

	    COLOR = vec4(color, 1.0);
	}
}