#[compute]

#version 450

#VERSION_DEFINES

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

layout(set = 0, binding = 1, std430) buffer restrict writeonly DstVertexData {
	uint data[];
}
dst_vertices;

layout(set = 0, binding = 2, std430) buffer restrict readonly BlendShapeWeights {
	float data[];
}
blend_shape_weights;

layout(set = 1, binding = 0, std430) buffer restrict readonly SrcVertexData {
	uint data[];
}
src_vertices;

layout(set = 1, binding = 1, std430) buffer restrict readonly BoneWeightData {
	uint data[];
}
src_bone_weights;

layout(set = 1, binding = 2, std430) buffer restrict readonly BlendShapeData {
	uint data[];
}
src_blend_shapes;

layout(set = 2, binding = 0, std430) buffer restrict readonly SkeletonData {
	vec4 data[];
}
bone_transforms;

layout(push_constant, std430) uniform Params {
	bool has_normal;
	bool has_tangent;
	bool has_skeleton;
	bool has_blend_shape;

	uint vertex_count;
	uint vertex_stride;
	uint skin_stride;
	uint skin_weight_offset;

	uint blend_shape_count;
	bool normalized_blend_shapes;
	uint pad0;
	uint pad1;
}
params;

vec2 uint_to_vec2(uint base) {
	uvec2 decode = (uvec2(base) >> uvec2(0, 16)) & uvec2(0xFFFF, 0xFFFF);
	return vec2(decode) / vec2(65535.0, 65535.0) * 2.0 - 1.0;
}

vec3 oct_to_vec3(vec2 oct) {
	vec3 v = vec3(oct.xy, 1.0 - abs(oct.x) - abs(oct.y));
	float t = max(-v.z, 0.0);
	v.xy += t * -sign(v.xy);
	return v;
}

vec3 decode_uint_oct_to_norm(uint base) {
	return oct_to_vec3(uint_to_vec2(base));
}

vec4 decode_uint_oct_to_tang(uint base) {
	vec2 oct_sign_encoded = uint_to_vec2(base);
	// Binormal sign encoded in y component
	vec2 oct = vec2(oct_sign_encoded.x, abs(oct_sign_encoded.y) * 2.0 - 1.0);
	return vec4(oct_to_vec3(oct), sign(oct_sign_encoded.y));
}

vec2 signNotZero(vec2 v) {
	return mix(vec2(-1.0), vec2(1.0), greaterThanEqual(v.xy, vec2(0.0)));
}

uint vec2_to_uint(vec2 base) {
	uvec2 enc = uvec2(clamp(ivec2(base * vec2(65535, 65535)), ivec2(0), ivec2(0xFFFF, 0xFFFF))) << uvec2(0, 16);
	return enc.x | enc.y;
}

vec2 vec3_to_oct(vec3 e) {
	e /= abs(e.x) + abs(e.y) + abs(e.z);
	vec2 oct = e.z >= 0.0f ? e.xy : (vec2(1.0f) - abs(e.yx)) * signNotZero(e.xy);
	return oct * 0.5f + 0.5f;
}

uint encode_norm_to_uint_oct(vec3 base) {
	return vec2_to_uint(vec3_to_oct(base));
}

uint encode_tang_to_uint_oct(vec4 base) {
	vec2 oct = vec3_to_oct(base.xyz);
	// Encode binormal sign in y component
	oct.y = oct.y * 0.5f + 0.5f;
	oct.y = base.w >= 0.0f ? oct.y : 1 - oct.y;
	return vec2_to_uint(oct);
}

void main() {
	uint index = gl_GlobalInvocationID.x;
	if (index >= params.vertex_count) {
		return;
	}

	uint src_offset = index * params.vertex_stride;

#ifdef MODE_2D
	vec2 vertex = uintBitsToFloat(uvec2(src_vertices.data[src_offset + 0], src_vertices.data[src_offset + 1]));

	if (params.has_blend_shape) {
		float blend_total = 0.0;
		vec2 blend_vertex = vec2(0.0);

		for (uint i = 0; i < params.blend_shape_count; i++) {
			float w = blend_shape_weights.data[i];
			if (abs(w) > 0.0001) {
				uint base_offset = (params.vertex_count * i + index) * params.vertex_stride;

				blend_vertex += uintBitsToFloat(uvec2(src_blend_shapes.data[base_offset + 0], src_blend_shapes.data[base_offset + 1])) * w;

				base_offset += 2;

				blend_total += w;
			}
		}

		if (params.normalized_blend_shapes) {
			vertex = (1.0 - blend_total) * vertex;
		}

		vertex += blend_vertex;
	}

	if (params.has_skeleton) {
		uint skin_offset = params.skin_stride * index;

		uvec2 bones = uvec2(src_bone_weights.data[skin_offset + 0], src_bone_weights.data[skin_offset + 1]);
		uvec2 bones_01 = uvec2(bones.x & 0xFFFF, bones.x >> 16) * 2; //pre-add xform offset
		uvec2 bones_23 = uvec2(bones.y & 0xFFFF, bones.y >> 16) * 2;

		skin_offset += params.skin_weight_offset;

		uvec2 weights = uvec2(src_bone_weights.data[skin_offset + 0], src_bone_weights.data[skin_offset + 1]);

		vec2 weights_01 = unpackUnorm2x16(weights.x);
		vec2 weights_23 = unpackUnorm2x16(weights.y);

		mat4 m = mat4(bone_transforms.data[bones_01.x], bone_transforms.data[bones_01.x + 1], vec4(0.0, 0.0, 1.0, 0.0), vec4(0.0, 0.0, 0.0, 1.0)) * weights_01.x;
		m += mat4(bone_transforms.data[bones_01.y], bone_transforms.data[bones_01.y + 1], vec4(0.0, 0.0, 1.0, 0.0), vec4(0.0, 0.0, 0.0, 1.0)) * weights_01.y;
		m += mat4(bone_transforms.data[bones_23.x], bone_transforms.data[bones_23.x + 1], vec4(0.0, 0.0, 1.0, 0.0), vec4(0.0, 0.0, 0.0, 1.0)) * weights_23.x;
		m += mat4(bone_transforms.data[bones_23.y], bone_transforms.data[bones_23.y + 1], vec4(0.0, 0.0, 1.0, 0.0), vec4(0.0, 0.0, 0.0, 1.0)) * weights_23.y;

		//reverse order because its transposed
		vertex = (vec4(vertex, 0.0, 1.0) * m).xy;
	}

	uint dst_offset = index * params.vertex_stride;

	uvec2 uvertex = floatBitsToUint(vertex);
	dst_vertices.data[dst_offset + 0] = uvertex.x;
	dst_vertices.data[dst_offset + 1] = uvertex.y;

#else
	vec3 vertex;
	vec3 normal;
	vec4 tangent;

	vertex = uintBitsToFloat(uvec3(src_vertices.data[src_offset + 0], src_vertices.data[src_offset + 1], src_vertices.data[src_offset + 2]));

	src_offset += 3;

	if (params.has_normal) {
		normal = decode_uint_oct_to_norm(src_vertices.data[src_offset]);
		src_offset++;
	}

	if (params.has_tangent) {
		tangent = decode_uint_oct_to_tang(src_vertices.data[src_offset]);
	}

	if (params.has_blend_shape) {
		float blend_total = 0.0;
		vec3 blend_vertex = vec3(0.0);
		vec3 blend_normal = vec3(0.0);
		vec3 blend_tangent = vec3(0.0);

		for (uint i = 0; i < params.blend_shape_count; i++) {
			float w = blend_shape_weights.data[i];
			if (abs(w) > 0.0001) {
				uint base_offset = (params.vertex_count * i + index) * params.vertex_stride;

				blend_vertex += uintBitsToFloat(uvec3(src_blend_shapes.data[base_offset + 0], src_blend_shapes.data[base_offset + 1], src_blend_shapes.data[base_offset + 2])) * w;

				base_offset += 3;

				if (params.has_normal) {
					blend_normal += decode_uint_oct_to_norm(src_blend_shapes.data[base_offset]) * w;
					base_offset++;
				}

				if (params.has_tangent) {
					blend_tangent += decode_uint_oct_to_tang(src_blend_shapes.data[base_offset]).rgb * w;
				}

				blend_total += w;
			}
		}

		if (params.normalized_blend_shapes) {
			vertex = (1.0 - blend_total) * vertex;
			normal = (1.0 - blend_total) * normal;
			tangent.rgb = (1.0 - blend_total) * tangent.rgb;
		}

		vertex += blend_vertex;
		normal = normalize(normal + blend_normal);
		tangent.rgb = normalize(tangent.rgb + blend_tangent);
	}

	if (params.has_skeleton) {
		uint skin_offset = params.skin_stride * index;

		uvec2 bones = uvec2(src_bone_weights.data[skin_offset + 0], src_bone_weights.data[skin_offset + 1]);
		uvec2 bones_01 = uvec2(bones.x & 0xFFFF, bones.x >> 16) * 3; //pre-add xform offset
		uvec2 bones_23 = uvec2(bones.y & 0xFFFF, bones.y >> 16) * 3;

		skin_offset += params.skin_weight_offset;

		uvec2 weights = uvec2(src_bone_weights.data[skin_offset + 0], src_bone_weights.data[skin_offset + 1]);

		vec2 weights_01 = unpackUnorm2x16(weights.x);
		vec2 weights_23 = unpackUnorm2x16(weights.y);

		mat4 m = mat4(bone_transforms.data[bones_01.x], bone_transforms.data[bones_01.x + 1], bone_transforms.data[bones_01.x + 2], vec4(0.0, 0.0, 0.0, 1.0)) * weights_01.x;
		m += mat4(bone_transforms.data[bones_01.y], bone_transforms.data[bones_01.y + 1], bone_transforms.data[bones_01.y + 2], vec4(0.0, 0.0, 0.0, 1.0)) * weights_01.y;
		m += mat4(bone_transforms.data[bones_23.x], bone_transforms.data[bones_23.x + 1], bone_transforms.data[bones_23.x + 2], vec4(0.0, 0.0, 0.0, 1.0)) * weights_23.x;
		m += mat4(bone_transforms.data[bones_23.y], bone_transforms.data[bones_23.y + 1], bone_transforms.data[bones_23.y + 2], vec4(0.0, 0.0, 0.0, 1.0)) * weights_23.y;

		if (params.skin_weight_offset == 4) {
			//using 8 bones/weights
			skin_offset = params.skin_stride * index + 2;

			bones = uvec2(src_bone_weights.data[skin_offset + 0], src_bone_weights.data[skin_offset + 1]);
			bones_01 = uvec2(bones.x & 0xFFFF, bones.x >> 16) * 3; //pre-add xform offset
			bones_23 = uvec2(bones.y & 0xFFFF, bones.y >> 16) * 3;

			skin_offset += params.skin_weight_offset;

			weights = uvec2(src_bone_weights.data[skin_offset + 0], src_bone_weights.data[skin_offset + 1]);

			weights_01 = unpackUnorm2x16(weights.x);
			weights_23 = unpackUnorm2x16(weights.y);

			m += mat4(bone_transforms.data[bones_01.x], bone_transforms.data[bones_01.x + 1], bone_transforms.data[bones_01.x + 2], vec4(0.0, 0.0, 0.0, 1.0)) * weights_01.x;
			m += mat4(bone_transforms.data[bones_01.y], bone_transforms.data[bones_01.y + 1], bone_transforms.data[bones_01.y + 2], vec4(0.0, 0.0, 0.0, 1.0)) * weights_01.y;
			m += mat4(bone_transforms.data[bones_23.x], bone_transforms.data[bones_23.x + 1], bone_transforms.data[bones_23.x + 2], vec4(0.0, 0.0, 0.0, 1.0)) * weights_23.x;
			m += mat4(bone_transforms.data[bones_23.y], bone_transforms.data[bones_23.y + 1], bone_transforms.data[bones_23.y + 2], vec4(0.0, 0.0, 0.0, 1.0)) * weights_23.y;
		}

		//reverse order because its transposed
		vertex = (vec4(vertex, 1.0) * m).xyz;
		normal = normalize((vec4(normal, 0.0) * m).xyz);
		tangent.xyz = normalize((vec4(tangent.xyz, 0.0) * m).xyz);
	}

	uint dst_offset = index * params.vertex_stride;

	uvec3 uvertex = floatBitsToUint(vertex);
	dst_vertices.data[dst_offset + 0] = uvertex.x;
	dst_vertices.data[dst_offset + 1] = uvertex.y;
	dst_vertices.data[dst_offset + 2] = uvertex.z;

	dst_offset += 3;

	if (params.has_normal) {
		dst_vertices.data[dst_offset] = encode_norm_to_uint_oct(normal);
		dst_offset++;
	}

	if (params.has_tangent) {
		dst_vertices.data[dst_offset] = encode_tang_to_uint_oct(tangent);
	}

#endif
}