dolphin/Source/Core/VideoCommon/Src/IndexGenerator.cpp

// Copyright (C) 2003 Dolphin Project.

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 2.0.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official SVN repository and contact information can be found at
// http://code.google.com/p/dolphin-emu/

#include <cstddef>

#include "Common.h"
#include "IndexGenerator.h"

/*
*
QUAD simulator

0   1   4   5
3   2   7   6
012023 147172 ...
*/

//Init
u16 *IndexGenerator::Tptr;
u16 *IndexGenerator::BASETptr;
u16 *IndexGenerator::Lptr;
u16 *IndexGenerator::BASELptr;
u16 *IndexGenerator::Pptr;
u16 *IndexGenerator::BASEPptr;
u32 IndexGenerator::numT;
u32 IndexGenerator::numL;
u32 IndexGenerator::numP;
u32 IndexGenerator::index;

void IndexGenerator::Start(u16* Triangleptr, u16* Lineptr, u16* Pointptr)
{
	Tptr = Triangleptr;
	Lptr = Lineptr;
	Pptr = Pointptr;
	BASETptr = Triangleptr;
	BASELptr = Lineptr;
	BASEPptr = Pointptr;
	index = 0;
	numT = 0;
	numL = 0;
	numP = 0;
}

void IndexGenerator::AddIndices(int primitive, u32 numVerts)
{
	//switch (primitive)
	//{
	//case GX_DRAW_QUADS:          IndexGenerator::AddQuads(numVerts);		break;
	//case GX_DRAW_TRIANGLES:      IndexGenerator::AddList(numVerts);		break;
	//case GX_DRAW_TRIANGLE_STRIP: IndexGenerator::AddStrip(numVerts);		break;
	//case GX_DRAW_TRIANGLE_FAN:   IndexGenerator::AddFan(numVerts);		break;
	//case GX_DRAW_LINES:		   IndexGenerator::AddLineList(numVerts);	break;
	//case GX_DRAW_LINE_STRIP:     IndexGenerator::AddLineStrip(numVerts);	break;
	//case GX_DRAW_POINTS:         IndexGenerator::AddPoints(numVerts);		break;
	//}

	static void (*const primitive_table[])(u32) =
	{
		IndexGenerator::AddQuads,
		NULL,
		IndexGenerator::AddList,
		IndexGenerator::AddStrip,
		IndexGenerator::AddFan,
		IndexGenerator::AddLineList,
		IndexGenerator::AddLineStrip,
		IndexGenerator::AddPoints,
	};

	primitive_table[primitive](numVerts);
	index += numVerts;
}

// Triangles
__forceinline void IndexGenerator::WriteTriangle(u32 index1, u32 index2, u32 index3)
{
	*Tptr++ = index1;
	*Tptr++ = index2;
	*Tptr++ = index3;

	++numT;
}

void IndexGenerator::AddList(u32 const numVerts)
{
	auto const numTris = numVerts / 3;
	for (u32 i = 0; i != numTris; ++i)
	{
		WriteTriangle(index + i * 3, index + i * 3 + 1, index + i * 3 + 2);
	}
}

void IndexGenerator::AddStrip(u32 const numVerts)
{
	bool wind = false;
	for (u32 i = 2; i < numVerts; ++i)
	{
		WriteTriangle(
			index + i - 2,
			index + i - !wind,
			index + i - wind);

		wind ^= true;
	}
}

void IndexGenerator::AddFan(u32 numVerts)
{
	for (u32 i = 2; i < numVerts; ++i)
	{
		WriteTriangle(index, index + i - 1, index + i);
	}
}

void IndexGenerator::AddQuads(u32 numVerts)
{
	auto const numQuads = numVerts / 4;
	for (u32 i = 0; i != numQuads; ++i)
	{
		WriteTriangle(index + i * 4, index + i * 4 + 1, index + i * 4 + 2);
		WriteTriangle(index + i * 4, index + i * 4 + 2, index + i * 4 + 3);
	}
}

// Lines
void IndexGenerator::AddLineList(u32 numVerts)
{
	auto const numLines = numVerts / 2;
	for (u32 i = 0; i != numLines; ++i)
	{
		*Lptr++ = index + i * 2;
		*Lptr++ = index + i * 2 + 1;
		++numL;
	}
}

void IndexGenerator::AddLineStrip(u32 numVerts)
{
	for (u32 i = 1; i < numVerts; ++i)
	{
		*Lptr++ = index + i - 1;
		*Lptr++ = index + i;
		++numL;
	}
}

// Points
void IndexGenerator::AddPoints(u32 numVerts)
{
	for (u32 i = 0; i != numVerts; ++i)
	{
		*Pptr++ = index + i;
		++numP;
	}
}