[compute]

#version 450

VERSION_DEFINES

layout(local_size_x = 64, local_size_y = 1, local_size_z = 1) in;

#define NO_CHILDREN 0xFFFFFFFF
#define GREY_VEC vec3(0.33333,0.33333,0.33333)

struct CellChildren {
	uint children[8];
};

layout(set=0,binding=1,std430) buffer CellChildrenBuffer {
    CellChildren data[];
} cell_children;

struct CellData {
	uint position; // xyz 10 bits
	uint albedo; //rgb albedo
	uint emission; //rgb normalized with e as multiplier
	uint normal; //RGB normal encoded
};

layout(set=0,binding=2,std430) buffer CellDataBuffer {
    CellData data[];
} cell_data;

#define LIGHT_TYPE_DIRECTIONAL 0
#define LIGHT_TYPE_OMNI 1
#define LIGHT_TYPE_SPOT 2

#ifdef MODE_COMPUTE_LIGHT

struct Light {

	uint type;
	float energy;
	float radius;
	float attenuation;

	vec3 color;
	float spot_angle_radians;

	vec3 position;
	float spot_attenuation;

	vec3 direction;
	bool has_shadow;
};


layout(set=0,binding=3,std140) uniform Lights {
    Light data[MAX_LIGHTS];
} lights;

#endif

layout(push_constant, binding = 0, std430) uniform Params {

	ivec3 limits;
	uint stack_size;

	float emission_scale;
	float propagation;
	float dynamic_range;

	uint light_count;
	uint cell_offset;
	uint cell_count;
	uint pad[2];

} params;


layout(set=0,binding=4,std140) uniform Outputs {
    vec4 data[];
} output;



#ifdef MODE_COMPUTE_LIGHT

uint raymarch(float distance,float distance_adv,vec3 from,vec3 direction) {

	uint result = NO_CHILDREN;

	ivec3 size = ivec3(max(max(params.limits.x,params.limits.y),params.limits.z));

	while (distance > -distance_adv) { //use this to avoid precision errors

		uint cell = 0;

		ivec3 pos = ivec3(from);

		if (all(greaterThanEqual(pos,ivec3(0))) && all(lessThan(pos,size))) {

			ivec3 ofs = ivec3(0);
			ivec3 half_size = size / 2;

			for (int i = 0; i < params.stack_size - 1; i++) {

				bvec3 greater = greaterThanEqual(pos,ofs+half_size);

				ofs += mix(ivec3(0),half_size,greater);

				uint child = 0; //wonder if this can be done faster
				if (greater.x) {
					child|=1;
				}
				if (greater.y) {
					child|=2;
				}
				if (greater.z) {
					child|=4;
				}

				cell = cell_children.data[cell].children[child];
				if (cell == NO_CHILDREN)
					break;

				half_size >>= ivec3(1);
			}

			if ( cell != NO_CHILDREN) {
				return cell; //found cell!
			}

		}

		from += direction * distance_adv;
		distance -= distance_adv;
	}

	return NO_CHILDREN;
}

bool compute_light_vector(uint light,uint cell, vec3 pos,out float attenuation, out vec3 light_pos) {


	if (lights.data[light].type==LIGHT_TYPE_DIRECTIONAL) {

		light_pos = pos - lights.data[light].direction * length(vec3(params.limits));
		attenuation = 1.0;

	} else {

		light_pos = lights.data[light].position;
		float distance = length(pos - light_pos);
		if (distance >= lights.data[light].radius) {
			return false;
		}


		attenuation = pow( clamp( 1.0 - distance / lights.data[light].radius, 0.0001, 1.0), lights.data[light].attenuation );


		if (lights.data[light].type==LIGHT_TYPE_SPOT) {

			vec3 rel = normalize(pos - light_pos);
			float angle = acos(dot(rel,lights.data[light].direction));
			if (angle > lights.data[light].spot_angle_radians) {
				return false;
			}

			float d = clamp(angle / lights.data[light].spot_angle_radians, 0, 1);
			attenuation *= pow(1.0 - d, lights.data[light].spot_attenuation);
		}
	}

	return true;
}

float get_normal_advance(vec3 p_normal) {

	vec3 normal = p_normal;
	vec3 unorm = abs(normal);

	if ((unorm.x >= unorm.y) && (unorm.x >= unorm.z)) {
		// x code
		unorm = normal.x > 0.0 ? vec3(1.0, 0.0, 0.0) : vec3(-1.0, 0.0, 0.0);
	} else if ((unorm.y > unorm.x) && (unorm.y >= unorm.z)) {
		// y code
		unorm = normal.y > 0.0 ? vec3(0.0, 1.0, 0.0) : vec3(0.0, -1.0, 0.0);
	} else if ((unorm.z > unorm.x) && (unorm.z > unorm.y)) {
		// z code
		unorm = normal.z > 0.0 ? vec3(0.0, 0.0, 1.0) : vec3(0.0, 0.0, -1.0);
	} else {
		// oh-no we messed up code
		// has to be
		unorm = vec3(1.0, 0.0, 0.0);
	}

	return 1.0 / dot(normal,unorm);
}

#endif




void main() {

	uint cell_index = gl_GlobalInvocationID.x;;
	if (cell_index >= params.cell_count) {
		return;
	}
	cell_index += params.cell_offset;

	uvec3 posu = uvec3(cell_data.data[cell_index].position&0x7FF,(cell_data.data[cell_index].position>>11)&0x3FF,cell_data.data[cell_index].position>>21);
	vec4 albedo = unpackUnorm4x8(cell_data.data[cell_index].albedo);

#ifdef MODE_COMPUTE_LIGHT

	vec3 pos = vec3(posu) + vec3(0.5);

	vec3 emission = vec3(ivec3(cell_data.data[cell_index].emission&0x3FF,(cell_data.data[cell_index].emission>>10)&0x7FF,cell_data.data[cell_index].emission>>21)) * params.emission_scale;
	vec4 normal = unpackSnorm4x8(cell_data.data[cell_index].normal);

#ifdef MODE_ANISOTROPIC
	vec3 accum[6]=vec3[](vec3(0.0),vec3(0.0),vec3(0.0),vec3(0.0),vec3(0.0),vec3(0.0));
	const vec3 accum_dirs[6]=vec3[](vec3(1.0,0.0,0.0),vec3(-1.0,0.0,0.0),vec3(0.0,1.0,0.0),vec3(0.0,-1.0,0.0),vec3(0.0,0.0,1.0),vec3(0.0,0.0,-1.0));
#else
	vec3 accum = vec3(0.0);
#endif

	for(uint i=0;i<params.light_count;i++) {

		float attenuation;
		vec3 light_pos;

		if (!compute_light_vector(i,cell_index,pos,attenuation,light_pos)) {
			continue;
		}

		vec3 light_dir = pos - light_pos;
		float distance = length(light_dir);
		light_dir=normalize(light_dir);

		if (length(normal.xyz) > 0.2 && dot(normal.xyz,light_dir)>=0) {
			continue; //not facing the light
		}

		if (lights.data[i].has_shadow) {

			float distance_adv = get_normal_advance(light_dir);


			distance += distance_adv - mod(distance, distance_adv); //make it reach the center of the box always

			vec3 from = pos - light_dir * distance; //approximate
			from -= sign(light_dir)*0.45; //go near the edge towards the light direction to avoid self occlusion



			uint result = raymarch(distance,distance_adv,from,light_dir);

			if (result != cell_index) {
				continue; //was occluded
			}
		}

		vec3 light = lights.data[i].color * albedo.rgb * attenuation * lights.data[i].energy;

#ifdef MODE_ANISOTROPIC
		for(uint j=0;j<6;j++) {
			accum[j]+=max(0.0,dot(accum_dir,-light_dir))*light+emission;
		}
#else
		if (length(normal.xyz) > 0.2) {
			accum+=max(0.0,dot(normal.xyz,-light_dir))*light+emission;
		} else {
			//all directions
			accum+=light+emission;
		}
#endif

	}

#ifdef MODE_ANISOTROPIC

	output.data[cell_index*6+0]=vec4(accum[0],0.0);
	output.data[cell_index*6+1]=vec4(accum[1],0.0);
	output.data[cell_index*6+2]=vec4(accum[2],0.0);
	output.data[cell_index*6+3]=vec4(accum[3],0.0);
	output.data[cell_index*6+4]=vec4(accum[4],0.0);
	output.data[cell_index*6+5]=vec4(accum[5],0.0);
#else
	output.data[cell_index]=vec4(accum,0.0);

#endif

#endif //MODE_COMPUTE_LIGHT


#ifdef MODE_UPDATE_MIPMAPS

	{
#ifdef MODE_ANISOTROPIC
		vec3 light_accum[6] = vec3[](vec3(0.0),vec3(0.0),vec3(0.0),vec3(0.0),vec3(0.0),vec3(0.0));
#else
		vec3 light_accum = vec3(0.0);
#endif
		float count = 0.0;
		for(uint i=0;i<8;i++) {
			uint child_index = cell_children.data[cell_index].children[i];
			if (child_index==NO_CHILDREN) {
				continue;
			}
#ifdef MODE_ANISOTROPIC
			light_accum[1] += output.data[child_index*6+0].rgb;
			light_accum[2] += output.data[child_index*6+1].rgb;
			light_accum[3] += output.data[child_index*6+2].rgb;
			light_accum[4] += output.data[child_index*6+3].rgb;
			light_accum[5] += output.data[child_index*6+4].rgb;
			light_accum[6] += output.data[child_index*6+5].rgb;

#else
			light_accum += output.data[child_index].rgb;

#endif

			count+=1.0;
		}

		float divisor = mix(8.0,count,params.propagation);
#ifdef MODE_ANISOTROPIC
		output.data[cell_index*6+0]=vec4(light_accum[0] / divisor,0.0);
		output.data[cell_index*6+1]=vec4(light_accum[1] / divisor,0.0);
		output.data[cell_index*6+2]=vec4(light_accum[2] / divisor,0.0);
		output.data[cell_index*6+3]=vec4(light_accum[3] / divisor,0.0);
		output.data[cell_index*6+4]=vec4(light_accum[4] / divisor,0.0);
		output.data[cell_index*6+5]=vec4(light_accum[5] / divisor,0.0);

#else
		output.data[cell_index]=vec4(light_accum / divisor,0.0);
#endif



	}
#endif

#ifdef MODE_WRITE_TEXTURE
	{



	}
#endif
}