#include <metal_stdlib>
using namespace metal;

struct Camera {
	float4x4 view_proj;
	float3 position;
};

struct Lighting {
	float3 direction;
	float3 color;
	float intensity;
};

struct VertexOutput {
	float4 position [[position]];
	float2 uv [[user(locn0)]];
};

struct FragmentOutput {
	float4 color [[user(locn0)]];
};

fragment FragmentOutput fs_main(VertexOutput input [[stage_in]],
	constant Lighting& lighting [[buffer(0)]],
	texture2d<float> diffuse_tex_tex [[texture(0)]],
	sampler diffuse_tex_samp [[sampler(0)]],
	texture2d<float> normal_tex_tex [[texture(1)]],
	sampler normal_tex_samp [[sampler(1)]]) {
	FragmentOutput __luma_output;
	float4 diffuse = diffuse_tex_tex.sample(diffuse_tex_samp, input.uv);
	float4 normal_sample = normal_tex_tex.sample(normal_tex_samp, input.uv);
	float3 n = normalize(((normal_sample.xyz * 2.0) - float3(1.0, 1.0, 1.0)));
	float3 l = normalize(lighting.direction);
	float ndotl = max(dot(n, l), 0.0);
	float3 lit = (((diffuse.rgb * lighting.color) * ndotl) * lighting.intensity);
	__luma_output.color = float4(lit, diffuse.a);
	return __luma_output;
}