/*
The MIT License (MIT)

Copyright (c) 2022 Google LLC
Copyright (c) 2022 Sascha Willems

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

struct VSInput
{
[[vk::location(0)]] float3 Pos : POSITION0;
[[vk::location(1)]] float3 Normal : NORMAL0;
[[vk::location(2)]] float2 UV : TEXCOORD0;
[[vk::location(3)]] float3 Color : COLOR0;

// Instanced attributes
[[vk::location(4)]] float3 instancePos : POSITION1;
[[vk::location(5)]] float3 instanceRot : TEXCOORD1;
[[vk::location(6)]] float instanceScale : TEXCOORD2;
[[vk::location(7)]] int instanceTexIndex : TEXCOORD3;
};

struct UBO
{
	float4x4 projection;
	float4x4 modelview;
	float4 lightPos;
	float locSpeed;
	float globSpeed;
};

cbuffer ubo : register(b0) { UBO ubo; }

struct VSOutput
{
	float4 Pos : SV_POSITION;
[[vk::location(0)]] float3 Normal : NORMAL0;
[[vk::location(1)]] float3 Color : COLOR0;
[[vk::location(2)]] float3 UV : TEXCOORD0;
[[vk::location(3)]] float3 ViewVec : TEXCOORD1;
[[vk::location(4)]] float3 LightVec : TEXCOORD2;
};

VSOutput main(VSInput input)
{
	VSOutput output = (VSOutput)0;
	output.Color = input.Color;
	output.UV = float3(input.UV, input.instanceTexIndex);

	// rotate around x
	float s = sin(input.instanceRot.x + ubo.locSpeed);
	float c = cos(input.instanceRot.x + ubo.locSpeed);

	float3x3 mx = { c, -s, 0.0,
					s, c, 0.0,
					0.0, 0.0, 1.0 };

	// rotate around y
	s = sin(input.instanceRot.y + ubo.locSpeed);
	c = cos(input.instanceRot.y + ubo.locSpeed);

	float3x3 my = { c, 0.0, -s,
					0.0, 1.0, 0.0,
					s, 0.0, c };

	// rot around z
	s = sin(input.instanceRot.z + ubo.locSpeed);
	c = cos(input.instanceRot.z + ubo.locSpeed);

	float3x3 mz = { 1.0, 0.0, 0.0,
					0.0, c, -s,
					0.0, s, c };

	float3x3 rotMat = mul(mz, mul(my, mx));

	float4x4 gRotMat;
	s = sin(input.instanceRot.y + ubo.globSpeed);
	c = cos(input.instanceRot.y + ubo.globSpeed);
	gRotMat[0] = float4(c, 0.0, -s, 0.0);
	gRotMat[1] = float4(0.0, 1.0, 0.0, 0.0);
	gRotMat[2] = float4(s, 0.0, c, 0.0);
	gRotMat[3] = float4(0.0, 0.0, 0.0, 1.0);

	float4 locPos = float4(mul(rotMat, input.Pos.xyz), 1.0);
	float4 pos = float4((locPos.xyz * input.instanceScale) + input.instancePos, 1.0);

	output.Pos = mul(ubo.projection, mul(ubo.modelview, mul(gRotMat, pos)));
	output.Normal = mul((float3x3)mul(ubo.modelview, gRotMat), mul(rotMat, input.Normal));

	pos = mul(ubo.modelview, float4(input.Pos.xyz + input.instancePos, 1.0));
	float3 lPos = mul((float3x3)ubo.modelview, ubo.lightPos.xyz);
	output.LightVec = lPos - pos.xyz;
	output.ViewVec = -pos.xyz;
	return output;
}