#[set(everything)]
const constants: {
	texel_size: float2;
};

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

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

struct vert_in {
	pos: float2;
}

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

fun depth_to_normal_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 depth_to_normal_pass_frag(input: vert_out): float4 {
	var ts: float2 = constants.texel_size;
	var h00: float = sample_lod(height_map, sampler_linear, input.tex + float2(-2.0, -2.0) * ts, 0.0).r;
	var h01: float = sample_lod(height_map, sampler_linear, input.tex + float2(-1.0, -2.0) * ts, 0.0).r;
	var h02: float = sample_lod(height_map, sampler_linear, input.tex + float2( 0.0, -2.0) * ts, 0.0).r;
	var h03: float = sample_lod(height_map, sampler_linear, input.tex + float2( 1.0, -2.0) * ts, 0.0).r;
	var h04: float = sample_lod(height_map, sampler_linear, input.tex + float2( 2.0, -2.0) * ts, 0.0).r;
	var h10: float = sample_lod(height_map, sampler_linear, input.tex + float2(-2.0, -1.0) * ts, 0.0).r;
	var h11: float = sample_lod(height_map, sampler_linear, input.tex + float2(-1.0, -1.0) * ts, 0.0).r;
	var h12: float = sample_lod(height_map, sampler_linear, input.tex + float2( 0.0, -1.0) * ts, 0.0).r;
	var h13: float = sample_lod(height_map, sampler_linear, input.tex + float2( 1.0, -1.0) * ts, 0.0).r;
	var h14: float = sample_lod(height_map, sampler_linear, input.tex + float2( 2.0, -1.0) * ts, 0.0).r;
	var h20: float = sample_lod(height_map, sampler_linear, input.tex + float2(-2.0,  0.0) * ts, 0.0).r;
	var h21: float = sample_lod(height_map, sampler_linear, input.tex + float2(-1.0,  0.0) * ts, 0.0).r;
	var h23: float = sample_lod(height_map, sampler_linear, input.tex + float2( 1.0,  0.0) * ts, 0.0).r;
	var h24: float = sample_lod(height_map, sampler_linear, input.tex + float2( 2.0,  0.0) * ts, 0.0).r;
	var h30: float = sample_lod(height_map, sampler_linear, input.tex + float2(-2.0,  1.0) * ts, 0.0).r;
	var h31: float = sample_lod(height_map, sampler_linear, input.tex + float2(-1.0,  1.0) * ts, 0.0).r;
	var h32: float = sample_lod(height_map, sampler_linear, input.tex + float2( 0.0,  1.0) * ts, 0.0).r;
	var h33: float = sample_lod(height_map, sampler_linear, input.tex + float2( 1.0,  1.0) * ts, 0.0).r;
	var h34: float = sample_lod(height_map, sampler_linear, input.tex + float2( 2.0,  1.0) * ts, 0.0).r;
	var h40: float = sample_lod(height_map, sampler_linear, input.tex + float2(-2.0,  2.0) * ts, 0.0).r;
	var h41: float = sample_lod(height_map, sampler_linear, input.tex + float2(-1.0,  2.0) * ts, 0.0).r;
	var h42: float = sample_lod(height_map, sampler_linear, input.tex + float2( 0.0,  2.0) * ts, 0.0).r;
	var h43: float = sample_lod(height_map, sampler_linear, input.tex + float2( 1.0,  2.0) * ts, 0.0).r;
	var h44: float = sample_lod(height_map, sampler_linear, input.tex + float2( 2.0,  2.0) * ts, 0.0).r;
	var dx: float = 2.0 * (h00 - h04) + 1.0 * (h01 - h03)
	              + 3.0 * (h10 - h14) + 2.0 * (h11 - h13)
	              + 4.0 * (h20 - h24) + 3.0 * (h21 - h23)
	              + 3.0 * (h30 - h34) + 2.0 * (h31 - h33)
	              + 2.0 * (h40 - h44) + 1.0 * (h41 - h43);
	var dy: float = 2.0 * (h40 - h00) + 3.0 * (h41 - h01) + 4.0 * (h42 - h02) + 3.0 * (h43 - h03) + 2.0 * (h44 - h04)
	              + 1.0 * (h30 - h10) + 2.0 * (h31 - h11) + 3.0 * (h32 - h12) + 2.0 * (h33 - h13) + 1.0 * (h34 - h14);
	var normal: float3 = normalize(float3(dx, dy, 1.4375));
	normal = normal * 0.5 + 0.5;
	return float4(normal.x, normal.y, normal.z, 1.0);
}

#[pipe]
struct pipe {
	vertex = depth_to_normal_pass_vert;
	fragment = depth_to_normal_pass_frag;
}