// Copyright (C) 2009-present, Panagiotis Christopoulos Charitos and contributors.
// All rights reserved.
// Code licensed under the BSD License.
// http://www.anki3d.org/LICENSE

#pragma anki mutator METHOD 0 1 2 // 0: solid colod, 1: 2D image, 2: generated

#pragma anki technique vert pixel

#define CUSTOM_DEPTH 1.0
#include <AnKi/Shaders/QuadVert.hlsl>

#if ANKI_PIXEL_SHADER
#	include <AnKi/Shaders/Include/MiscRendererTypes.h>
#	include <AnKi/Shaders/Functions.hlsl>
#	include <AnKi/Shaders/TonemappingFunctions.hlsl>
#	include <AnKi/Shaders/Sky.hlsl>

#	if METHOD == 0
struct Constants
{
	Vec3 m_solidColor;
	F32 m_padding;
};

ANKI_FAST_CONSTANTS(Constants, g_consts)
#	elif METHOD == 1
SamplerState g_trilinearAnySampler : register(s0);
Texture2D<Vec4> g_envMapTex : register(t0);

struct Constants
{
	Mat4 m_invertedViewProjectionJitterMat;

	Vec3 m_cameraPos;
	F32 m_padding;

	Vec3 m_scale;
	F32 m_padding1;

	Vec3 m_bias;
	F32 m_padding2;
};

ANKI_FAST_CONSTANTS(Constants, g_consts)
#	else
SamplerState g_linearAnyClampSampler : register(s0);
Texture2D<Vec4> g_skyLut : register(t0);
ConstantBuffer<GlobalRendererConstants> g_consts : register(b0);
#	endif

Vec4 main(VertOut input) : SV_TARGET0
{
	const Vec2 uv = input.m_uv;
#	if METHOD == 0
	ANKI_MAYBE_UNUSED(uv);
	const Vec3 output = g_consts.m_solidColor;
#	elif METHOD == 1
	const F32 depth = 1.0;
	const Vec2 ndc = uvToNdc(uv);
	const Vec4 worldPos4 = mul(g_consts.m_invertedViewProjectionJitterMat, Vec4(ndc, depth, 1.0));
	const Vec3 worldPos = worldPos4.xyz / worldPos4.w;

	const Vec3 eyeToFrag = normalize(worldPos - g_consts.m_cameraPos);

	const Vec2 uv3 = equirectangularMapping(eyeToFrag);

	// When uv is close to the edge of the texture the other quads might be in the oposit coordinate. Then the
	// derivatives will be huge causing the texture to use the highest mip and thus create a visible seam. To fix this
	// find when the derivatives are large and do some manual work to fix it
	const Vec2 dx = abs(ddx_coarse(uv3));
	const F32 maxD = max(dx.x, dx.y);

	const F32 bias = (maxD > 0.9) ? -100.0f : 0.0f;

	const Vec3 output = g_envMapTex.SampleBias(g_trilinearAnySampler, uv3, bias).rgb * g_consts.m_scale + g_consts.m_bias;
#	else
	const F32 depth = 1.0;
	const Vec2 ndc = uvToNdc(uv);
	const Vec4 worldPos4 = mul(g_consts.m_matrices.m_invertedViewProjectionJitter, Vec4(ndc, depth, 1.0));
	const Vec3 worldPos = worldPos4.xyz / worldPos4.w;

	const Vec3 eyeToFrag = normalize(worldPos - g_consts.m_cameraPosition);

	const Vec3 output = computeSkyColor(g_skyLut, g_linearAnyClampSampler, eyeToFrag, -g_consts.m_directionalLight.m_direction,
										g_consts.m_directionalLight.m_power, true);
#	endif

	return Vec4(output, 0.0);
}
#endif // ANKI_PIXEL_SHADER