bgfx/3rdparty/ib-compress/indexbuffercompression.h

/*
Copyright (c) 2014, Conor Stokes
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef INDEX_BUFFER_COMPRESSION_H__
#define INDEX_BUFFER_COMPRESSION_H__
#pragma once

#include <stdint.h>
#include "WriteBitstream.h"

// Compress an index buffer, writing the results out to a bitstream and providing a vertex remapping (which will be in pre-transform cache optimised
// order).
//
// This version has slightly worse compression and the matching decompression has worse performance than CompressIndexBuffer2, but it supports degenerate triangles 
// (that have duplicate vertex indices). Output should be decompressed with DecompressIndexBuffer. It also changes the order of the vertices in each triangle less.
//
// It works by outputting a code (along with any required index symbols) per vertex.
//
// Parameters: 
//     [in]  triangles      - A typical triangle list index buffer (3 indices to vertices per triangle). 16 bit indices.
//     [in]  triangle count - The number of triangles to process.
//     [out] vertexRemap    - This will be populated with re-mappings that map old vertices to new vertices,
//                            where indexing with the old vertex index will get you the new one. 
//                            It should be allocated as a with at least vertexCount entries.
//     [in] vertexCount     - The number of vertices in the mesh. This should be less than 0xFFFFFFFF/2^32 - 1.
//     [in] output          - The stream that the compressed data will be written to. Note that we will not flush/finish the stream
//                            in case something else is going to be written after, so WriteBitstream::Finish will need to be called after this.
void CompressIndexBuffer( const uint16_t* triangles, uint32_t triangleCount, uint32_t* vertexRemap, uint32_t vertexCount, WriteBitstream& output );

// Same as above but 32bit indices.
void CompressIndexBuffer( const uint32_t* triangles, uint32_t triangleCount, uint32_t* vertexRemap, uint32_t vertexCount, WriteBitstream& output );


// Compress an index buffer, writing the results out to a bitstream and providing a vertex remapping (which will be in pre-transform cache optimised
// order).
//
// This version has slightly better compression and the matching decompression has better performance than CompressIndexBuffer, but it does not supports degenerate triangles 
// (that have duplicate vertex indices). Output should be decompressed with DecompressIndexBuffer2. It changes the order of the vertices in each triangle more.
//
// This version also has compression optimisations that allow it to handle strip/fan cases a lot better compression wise.
//
// This works by outputting a code per triangle (along with the required index symbols).
//
// Parameters: 
//     [in]  triangles      - A typical triangle list index buffer (3 indices to vertices per triangle).
//     [in]  triangle count - The number of triangles to process.
//     [out] vertexRemap    - This will be populated with re-mappings that map old vertices to new vertices,
//                            where indexing with the old vertex index will get you the new one. 
//                            It should be allocated as a with at least vertexCount entries.
//     [in] vertexCount     - The number of vertices in the mesh. This should be less than 0xFFFFFFFF/2^32 - 1.
//     [in] output          - The stream that the compressed data will be written to. Note that we will not flush/finish the stream
//                            in case something else is going to be written after, so WriteBitstream::Finish will need to be called after this.
void CompressIndexBuffer2( const uint16_t* triangles, uint32_t triangleCount, uint32_t* vertexRemap, uint32_t vertexCount, WriteBitstream& output );

// Same as above but 32bit indices
void CompressIndexBuffer2( const uint32_t* triangles, uint32_t triangleCount, uint32_t* vertexRemap, uint32_t vertexCount, WriteBitstream& output );


#endif // -- INDEX_BUFFER_COMPRESSION_H__