#[set(everything)]
const constants: {
	N: float3x3;
	WVP: float4x4;
	tex_unpack: float;
};

struct vert_in {
	pos: float4;
	nor: float2;
	tex: float2;
}

struct vert_out {
	pos: float4;
	tex: float2;
	wnormal: float3;
}

fun mesh_posnortex_vert(input: vert_in): vert_out {
	var output: vert_out;
	output.pos = constants.WVP * float4(input.pos.xyz, 1.0);
	output.tex = input.tex * constants.tex_unpack;
	output.wnormal = normalize(constants.N * float3(input.nor.xy, input.pos.w));
	return output;
}

fun octahedron_wrap(v: float2): float2 {
	var a: float2;
	if (v.x >= 0.0) {
		a.x = 1.0;
	}
	else {
		a.x = -1.0;
	}

	if (v.y >= 0.0) {
		a.y = 1.0;
	}
	else {
		a.y = -1.0;
	}

	var r: float2;
	r.x = abs(v.y);
	r.y = abs(v.x);
	r.x = 1.0 - r.x;
	r.y = 1.0 - r.y;
	return r * a;

	// return (1.0 - abs(v.yx)) * (float2(v.x >= 0.0 ? 1.0 : -1.0, v.y >= 0.0 ? 1.0 : -1.0));
}

fun pack_f32_i16(f: float, i: uint): float {
	// GBuffer helper - Sebastien Lagarde
	// https://seblagarde.wordpress.com/2018/09/02/gbuffer-helper-packing-integer-and-float-together/
	// const num_bit_target: int = 16;
	// const num_bit_i: int = 4;
	// const prec: float = float(1 << num_bit_target);
	// const maxi: float = float(1 << num_bit_i);
	// const prec_minus_one: float = prec - 1.0;
	// const t1: float = ((prec / maxi) - 1.0) / prec_minus_one;
	// const t2: float = (prec / maxi) / prec_minus_one;
	// return t1 * f + t2 * float(i);
	return 0.062504762 * f + 0.062519999 * float(i);
}

fun mesh_posnortex_frag(input: vert_out): float4[2] {
	var n: float3 = normalize(input.wnormal);
	var basecol: float3 = float3(0.2, 0.2, 0.2) + input.tex.x * 0.0000001; // keep tex_coord
	var roughness: float = 0.4;
	var metallic: float = 0.0;
	var occlusion: float = 1.0;

	n /= abs(n.x) + abs(n.y) + abs(n.z);
	if (n.z >= 0.0) {
		n.xy = n.xy;
	}
	else {
		n.xy = octahedron_wrap(n.xy);
	}

	var matid: uint = 0;
	var color: float4[2];
	color[0].rgba = float4(n.xy, roughness, pack_f32_i16(metallic, matid));
	color[1].rgba = float4(basecol, occlusion);
	return color;
}

#[pipe]
struct pipe {
	vertex = mesh_posnortex_vert;
	fragment = mesh_posnortex_frag;
}