#[set(everything)]
const constants: {
	vignette_strength: float;
	grain_strength: float;
	tonemap_strength: float; // 0.0 or 1.0
	lut_size: float;
};

#[set(everything)]
const sampler_linear: sampler;

#[set(everything)]
const tex: tex2d;

#[set(everything)]
const lut_tex: tex2d;

// #[set(everything)]
// const histogram: tex2d;

struct vert_in {
	pos: float2;
}

struct vert_out {
	pos: float4;
	tex: float2;
}

fun compositor_pass_vert(input: vert_in): vert_out {
	var output: vert_out;
	output.tex = input.pos.xy * 0.5 + 0.5;
	output.tex.y = 1.0 - output.tex.y;
	output.pos = float4(input.pos.xy, 0.0, 1.0);
	return output;
}

fun tonemap_filmic(color: float3): float3 {
	// Based on Filmic Tonemapping Operators http://filmicgames.com/archives/75
	// var x: float3 = max(float3(0.0, 0.0, 0.0), color - 0.004);
	var x: float3;
	x.x = max(0.0, color.x - 0.004);
	x.y = max(0.0, color.y - 0.004);
	x.z = max(0.0, color.z - 0.004);
	return (x * (x * 6.2 + 0.5)) / (x * (x * 6.2 + 1.7) + 0.06);
}

fun compositor_pass_frag(input: vert_out): float4 {
	var color: float4 = sample_lod(tex, sampler_linear, input.tex, 0.0);

	// Static grain
	var x: float = (input.tex.x + 4.0) * (input.tex.y + 4.0) * 10.0;
	var g: float = (((x % 13.0) + 1.0) * ((x % 123.0) + 1.0) % 0.01) - 0.005;
	color.rgb = color.rgb + (float3(g, g, g) * constants.grain_strength);

	// Vignette
	color.rgb = color.rgb * ((1.0 - constants.vignette_strength) + constants.vignette_strength * pow(16.0 * input.tex.x * input.tex.y * (1.0 - input.tex.x) * (1.0 - input.tex.y), 0.2));

	// Auto exposure
	// const auto_exposure_strength: float = 1.0;
	// var expo: float = 2.0 - clamp(length(sample_lod(histogram, sampler_linear, float2(0.5, 0.5), 0.0).rgb), 0.0, 1.0);
	// color.rgb *= pow(expo, auto_exposure_strength * 2.0);

	if (constants.lut_size > 0.0) {
		// .cube lut color grading
		color.rgb = pow3(max3(color.rgb, float3(0.0, 0.0, 0.0)), float3(0.4545, 0.4545, 0.4545));
		var r_s: float = min(max(color.x, 0.0), 1.0) * (constants.lut_size - 1.0);
		var g_s: float = min(max(color.y, 0.0), 1.0) * (constants.lut_size - 1.0);
		var b_s: float = min(max(color.z, 0.0), 1.0) * (constants.lut_size - 1.0);
		var b0: float = floor(b_s);
		var b1: float = min(b0 + 1.0, constants.lut_size - 1.0);
		var b_frac: float = b_s - b0;
		var strip_w: float = constants.lut_size * constants.lut_size;
		var u0: float = (b0 * constants.lut_size + r_s + 0.5) / strip_w;
		var u1: float = (b1 * constants.lut_size + r_s + 0.5) / strip_w;
		var v: float = (g_s + 0.5) / constants.lut_size;
		var s0: float4 = sample_lod(lut_tex, sampler_linear, float2(u0, v), 0.0);
		var s1: float4 = sample_lod(lut_tex, sampler_linear, float2(u1, v), 0.0);
		color.rgb = lerp3(s0.rgb, s1.rgb, float3(b_frac, b_frac, b_frac));
	}
	else {
		// Tonemap with gamma
		color.rgb = lerp3(color.rgb, tonemap_filmic(color.rgb), constants.tonemap_strength);
	}

	return color;
}

#[pipe]
struct pipe {
	vertex = compositor_pass_vert;
	fragment = compositor_pass_frag;
}