// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "QuadRasterizer.hpp"

#include "Primitive.hpp"
#include "Renderer.hpp"
#include "Pipeline/Constants.hpp"
#include "System/Math.hpp"
#include "Vulkan/VkDebug.hpp"

namespace sw
{
	QuadRasterizer::QuadRasterizer(const PixelProcessor::State &state, SpirvShader const *spirvShader) : state(state), spirvShader{spirvShader}
	{
	}

	QuadRasterizer::~QuadRasterizer()
	{
	}

	void QuadRasterizer::generate()
	{
		constants = *Pointer<Pointer<Byte>>(data + OFFSET(DrawData,constants));
		occlusion = 0;

		Do
		{
			Int yMin = *Pointer<Int>(primitive + OFFSET(Primitive,yMin));
			Int yMax = *Pointer<Int>(primitive + OFFSET(Primitive,yMax));

			Int cluster2 = cluster + cluster;
			yMin += clusterCount * 2 - 2 - cluster2;
			yMin &= -clusterCount * 2;
			yMin += cluster2;

			If(yMin < yMax)
			{
				rasterize(yMin, yMax);
			}

			primitive += sizeof(Primitive) * state.multiSample;
			count--;
		}
		Until(count == 0)

		if(state.occlusionEnabled)
		{
			UInt clusterOcclusion = *Pointer<UInt>(data + OFFSET(DrawData,occlusion) + 4 * cluster);
			clusterOcclusion += occlusion;
			*Pointer<UInt>(data + OFFSET(DrawData,occlusion) + 4 * cluster) = clusterOcclusion;
		}

		Return();
	}

	void QuadRasterizer::rasterize(Int &yMin, Int &yMax)
	{
		Pointer<Byte> cBuffer[RENDERTARGETS];
		Pointer<Byte> zBuffer;
		Pointer<Byte> sBuffer;

		Int clusterCountLog2 = 31 - Ctlz(UInt(clusterCount), false);

		for(int index = 0; index < RENDERTARGETS; index++)
		{
			if(state.colorWriteActive(index))
			{
				cBuffer[index] = *Pointer<Pointer<Byte>>(data + OFFSET(DrawData,colorBuffer[index])) + yMin * *Pointer<Int>(data + OFFSET(DrawData,colorPitchB[index]));
			}
		}

		if(state.depthTestActive)
		{
			zBuffer = *Pointer<Pointer<Byte>>(data + OFFSET(DrawData,depthBuffer)) + yMin * *Pointer<Int>(data + OFFSET(DrawData,depthPitchB));
		}

		if(state.stencilActive)
		{
			sBuffer = *Pointer<Pointer<Byte>>(data + OFFSET(DrawData,stencilBuffer)) + yMin * *Pointer<Int>(data + OFFSET(DrawData,stencilPitchB));
		}

		Int y = yMin;

		Do
		{
			Int x0a = Int(*Pointer<Short>(primitive + OFFSET(Primitive,outline->left) + (y + 0) * sizeof(Primitive::Span)));
			Int x0b = Int(*Pointer<Short>(primitive + OFFSET(Primitive,outline->left) + (y + 1) * sizeof(Primitive::Span)));
			Int x0 = Min(x0a, x0b);

			for(unsigned int q = 1; q < state.multiSample; q++)
			{
				x0a = Int(*Pointer<Short>(primitive + q * sizeof(Primitive) + OFFSET(Primitive,outline->left) + (y + 0) * sizeof(Primitive::Span)));
				x0b = Int(*Pointer<Short>(primitive + q * sizeof(Primitive) + OFFSET(Primitive,outline->left) + (y + 1) * sizeof(Primitive::Span)));
				x0 = Min(x0, Min(x0a, x0b));
			}

			x0 &= 0xFFFFFFFE;

			Int x1a = Int(*Pointer<Short>(primitive + OFFSET(Primitive,outline->right) + (y + 0) * sizeof(Primitive::Span)));
			Int x1b = Int(*Pointer<Short>(primitive + OFFSET(Primitive,outline->right) + (y + 1) * sizeof(Primitive::Span)));
			Int x1 = Max(x1a, x1b);

			for(unsigned int q = 1; q < state.multiSample; q++)
			{
				x1a = Int(*Pointer<Short>(primitive + q * sizeof(Primitive) + OFFSET(Primitive,outline->right) + (y + 0) * sizeof(Primitive::Span)));
				x1b = Int(*Pointer<Short>(primitive + q * sizeof(Primitive) + OFFSET(Primitive,outline->right) + (y + 1) * sizeof(Primitive::Span)));
				x1 = Max(x1, Max(x1a, x1b));
			}

			Float4 yyyy = Float4(Float(y)) + *Pointer<Float4>(primitive + OFFSET(Primitive,yQuad), 16);

			if(interpolateZ())
			{
				for(unsigned int q = 0; q < state.multiSample; q++)
				{
					Float4 y = yyyy;

					if(state.multiSample > 1)
					{
						y -= *Pointer<Float4>(constants + OFFSET(Constants,Y) + q * sizeof(float4));
					}

					Dz[q] = *Pointer<Float4>(primitive + OFFSET(Primitive,z.C), 16) + y * *Pointer<Float4>(primitive + OFFSET(Primitive,z.B), 16);
				}
			}

			If(x0 < x1)
			{
				if(interpolateW())
				{
					Dw = *Pointer<Float4>(primitive + OFFSET(Primitive,w.C), 16) + yyyy * *Pointer<Float4>(primitive + OFFSET(Primitive,w.B), 16);
				}

				if (spirvShader)
				{
					for (int interpolant = 0; interpolant < MAX_INTERFACE_COMPONENTS; interpolant++)
					{
						if (spirvShader->inputs[interpolant].Type == SpirvShader::ATTRIBTYPE_UNUSED)
							continue;

						Dv[interpolant] = *Pointer<Float4>(primitive + OFFSET(Primitive, V[interpolant].C), 16);
						if (!spirvShader->inputs[interpolant].Flat)
						{
							Dv[interpolant] +=
									yyyy * *Pointer<Float4>(primitive + OFFSET(Primitive, V[interpolant].B), 16);
						}
					}
				}

				Short4 xLeft[4];
				Short4 xRight[4];

				for(unsigned int q = 0; q < state.multiSample; q++)
				{
					xLeft[q] = *Pointer<Short4>(primitive + q * sizeof(Primitive) + OFFSET(Primitive,outline) + y * sizeof(Primitive::Span));
					xRight[q] = xLeft[q];

					xLeft[q] = Swizzle(xLeft[q], 0xA0) - Short4(1, 2, 1, 2);
					xRight[q] = Swizzle(xRight[q], 0xF5) - Short4(0, 1, 0, 1);
				}

				For(Int x = x0, x < x1, x += 2)
				{
					Short4 xxxx = Short4(x);
					Int cMask[4];

					for(unsigned int q = 0; q < state.multiSample; q++)
					{
						if (state.multiSampleMask & (1<<q))
						{
							Short4 mask = CmpGT(xxxx, xLeft[q]) & CmpGT(xRight[q], xxxx);
							cMask[q] = SignMask(PackSigned(mask, mask)) & 0x0000000F;
						}
						else
						{
							cMask[q] = 0;
						}
					}

					quad(cBuffer, zBuffer, sBuffer, cMask, x, y);
				}
			}

			for(int index = 0; index < RENDERTARGETS; index++)
			{
				if(state.colorWriteActive(index))
				{
					cBuffer[index] += *Pointer<Int>(data + OFFSET(DrawData,colorPitchB[index])) << (1 + clusterCountLog2);   // FIXME: Precompute
				}
			}

			if(state.depthTestActive)
			{
				zBuffer += *Pointer<Int>(data + OFFSET(DrawData,depthPitchB)) << (1 + clusterCountLog2);   // FIXME: Precompute
			}

			if(state.stencilActive)
			{
				sBuffer += *Pointer<Int>(data + OFFSET(DrawData,stencilPitchB)) << (1 + clusterCountLog2);   // FIXME: Precompute
			}

			y += 2 * clusterCount;
		}
		Until(y >= yMax)
	}

	Float4 QuadRasterizer::interpolate(Float4 &x, Float4 &D, Float4 &rhw, Pointer<Byte> planeEquation, bool flat, bool perspective, bool clamp)
	{
		Float4 interpolant = D;

		if(!flat)
		{
			interpolant += x * *Pointer<Float4>(planeEquation + OFFSET(PlaneEquation, A), 16);

			if(perspective)
			{
				interpolant *= rhw;
			}
		}

		if(clamp)
		{
			interpolant = Min(Max(interpolant, Float4(0.0f)), Float4(1.0f));
		}

		return interpolant;
	}

	bool QuadRasterizer::interpolateZ() const
	{
		return state.depthTestActive || (spirvShader && spirvShader->hasBuiltinInput(spv::BuiltInFragCoord));
	}

	bool QuadRasterizer::interpolateW() const
	{
		// Note: could optimize cases where there is a fragment shader but it has no
		// perspective-correct inputs, but that's vanishingly rare.
		return spirvShader != nullptr;
	}
}