forked from 0ad/0ad
356 lines
10 KiB
C++
356 lines
10 KiB
C++
/* Copyright (C) 2016 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* encapsulation of VBOs with sharing
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*/
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#include "precompiled.h"
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#include "ps/Errors.h"
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#include "lib/ogl.h"
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#include "lib/sysdep/cpu.h"
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#include "Renderer.h"
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#include "VertexBuffer.h"
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#include "VertexBufferManager.h"
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#include "ps/CLogger.h"
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// Absolute maximum (bytewise) size of each GL vertex buffer object.
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// Make it large enough for the maximum feasible mesh size (64K vertexes,
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// 64 bytes per vertex in InstancingModelRenderer).
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// TODO: measure what influence this has on performance
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#define MAX_VB_SIZE_BYTES (4*1024*1024)
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CVertexBuffer::CVertexBuffer(size_t vertexSize, GLenum usage, GLenum target)
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: m_VertexSize(vertexSize), m_Handle(0), m_SysMem(0), m_Usage(usage), m_Target(target)
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{
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size_t size = MAX_VB_SIZE_BYTES;
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if (target == GL_ARRAY_BUFFER) // vertex data buffer
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{
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// We want to store 16-bit indices to any vertex in a buffer, so the
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// buffer must never be bigger than vertexSize*64K bytes since we can
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// address at most 64K of them with 16-bit indices
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size = std::min(size, vertexSize*65536);
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}
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// store max/free vertex counts
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m_MaxVertices = m_FreeVertices = size / vertexSize;
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// allocate raw buffer
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if (g_Renderer.m_Caps.m_VBO)
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{
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pglGenBuffersARB(1, &m_Handle);
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pglBindBufferARB(m_Target, m_Handle);
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pglBufferDataARB(m_Target, m_MaxVertices * m_VertexSize, 0, m_Usage);
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pglBindBufferARB(m_Target, 0);
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}
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else
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{
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m_SysMem = new u8[m_MaxVertices * m_VertexSize];
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}
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// create sole free chunk
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VBChunk* chunk = new VBChunk;
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chunk->m_Owner = this;
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chunk->m_Count = m_FreeVertices;
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chunk->m_Index = 0;
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m_FreeList.push_front(chunk);
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}
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CVertexBuffer::~CVertexBuffer()
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{
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// Must have released all chunks before destroying the buffer
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ENSURE(m_AllocList.empty());
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if (m_Handle)
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pglDeleteBuffersARB(1, &m_Handle);
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delete[] m_SysMem;
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typedef std::list<VBChunk*>::iterator Iter;
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for (Iter iter = m_FreeList.begin(); iter != m_FreeList.end(); ++iter)
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delete *iter;
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}
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bool CVertexBuffer::CompatibleVertexType(size_t vertexSize, GLenum usage, GLenum target)
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{
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if (usage != m_Usage || target != m_Target || vertexSize != m_VertexSize)
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return false;
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return true;
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}
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///////////////////////////////////////////////////////////////////////////////
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// Allocate: try to allocate a buffer of given number of vertices (each of
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// given size), with the given type, and using the given texture - return null
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// if no free chunks available
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CVertexBuffer::VBChunk* CVertexBuffer::Allocate(size_t vertexSize, size_t numVertices, GLenum usage, GLenum target, void* backingStore)
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{
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// check this is the right kind of buffer
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if (!CompatibleVertexType(vertexSize, usage, target))
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return 0;
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if (UseStreaming(usage))
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ENSURE(backingStore != NULL);
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// quick check there's enough vertices spare to allocate
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if (numVertices > m_FreeVertices)
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return 0;
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// trawl free list looking for first free chunk with enough space
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VBChunk* chunk = 0;
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typedef std::list<VBChunk*>::iterator Iter;
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for (Iter iter = m_FreeList.begin(); iter != m_FreeList.end(); ++iter) {
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if (numVertices <= (*iter)->m_Count) {
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chunk = *iter;
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// remove this chunk from the free list
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m_FreeList.erase(iter);
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m_FreeVertices -= chunk->m_Count;
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// no need to search further ..
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break;
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}
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}
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if (!chunk) {
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// no big enough spare chunk available
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return 0;
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}
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chunk->m_BackingStore = backingStore;
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chunk->m_Dirty = false;
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chunk->m_Needed = false;
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// split chunk into two; - allocate a new chunk using all unused vertices in the
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// found chunk, and add it to the free list
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if (chunk->m_Count > numVertices)
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{
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VBChunk* newchunk = new VBChunk;
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newchunk->m_Owner = this;
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newchunk->m_Count = chunk->m_Count - numVertices;
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newchunk->m_Index = chunk->m_Index + numVertices;
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m_FreeList.push_front(newchunk);
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m_FreeVertices += newchunk->m_Count;
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// resize given chunk
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chunk->m_Count = numVertices;
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}
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// return found chunk
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m_AllocList.push_back(chunk);
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return chunk;
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}
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///////////////////////////////////////////////////////////////////////////////
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// Release: return given chunk to this buffer
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void CVertexBuffer::Release(VBChunk* chunk)
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{
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// Update total free count before potentially modifying this chunk's count
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m_FreeVertices += chunk->m_Count;
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m_AllocList.remove(chunk);
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typedef std::list<VBChunk*>::iterator Iter;
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// Coalesce with any free-list items that are adjacent to this chunk;
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// merge the found chunk with the new one, and remove the old one
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// from the list, and repeat until no more are found
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bool coalesced;
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do
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{
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coalesced = false;
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for (Iter iter = m_FreeList.begin(); iter != m_FreeList.end(); ++iter)
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{
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if ((*iter)->m_Index == chunk->m_Index + chunk->m_Count
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|| (*iter)->m_Index + (*iter)->m_Count == chunk->m_Index)
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{
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chunk->m_Index = std::min(chunk->m_Index, (*iter)->m_Index);
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chunk->m_Count += (*iter)->m_Count;
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delete *iter;
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m_FreeList.erase(iter);
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coalesced = true;
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break;
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}
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}
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}
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while (coalesced);
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m_FreeList.push_front(chunk);
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}
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///////////////////////////////////////////////////////////////////////////////
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// UpdateChunkVertices: update vertex data for given chunk
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void CVertexBuffer::UpdateChunkVertices(VBChunk* chunk, void* data)
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{
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if (g_Renderer.m_Caps.m_VBO)
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{
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ENSURE(m_Handle);
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if (UseStreaming(m_Usage))
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{
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// The VBO is now out of sync with the backing store
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chunk->m_Dirty = true;
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// Sanity check: Make sure the caller hasn't tried to reallocate
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// their backing store
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ENSURE(data == chunk->m_BackingStore);
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}
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else
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{
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pglBindBufferARB(m_Target, m_Handle);
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pglBufferSubDataARB(m_Target, chunk->m_Index * m_VertexSize, chunk->m_Count * m_VertexSize, data);
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pglBindBufferARB(m_Target, 0);
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}
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}
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else
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{
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ENSURE(m_SysMem);
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memcpy(m_SysMem + chunk->m_Index * m_VertexSize, data, chunk->m_Count * m_VertexSize);
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}
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}
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///////////////////////////////////////////////////////////////////////////////
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// Bind: bind to this buffer; return pointer to address required as parameter
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// to glVertexPointer ( + etc) calls
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u8* CVertexBuffer::Bind()
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{
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if (!g_Renderer.m_Caps.m_VBO)
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return m_SysMem;
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pglBindBufferARB(m_Target, m_Handle);
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if (UseStreaming(m_Usage))
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{
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// If any chunks are out of sync with the current VBO, and are
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// needed for rendering this frame, we'll need to re-upload the VBO
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bool needUpload = false;
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for (VBChunk* const& chunk : m_AllocList)
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{
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if (chunk->m_Dirty && chunk->m_Needed)
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{
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needUpload = true;
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break;
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}
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}
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if (needUpload)
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{
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// Tell the driver that it can reallocate the whole VBO
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pglBufferDataARB(m_Target, m_MaxVertices * m_VertexSize, NULL, m_Usage);
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// (In theory, glMapBufferRange with GL_MAP_INVALIDATE_BUFFER_BIT could be used
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// here instead of glBufferData(..., NULL, ...) plus glMapBuffer(), but with
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// current Intel Windows GPU drivers (as of 2015-01) it's much faster if you do
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// the explicit glBufferData.)
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while (true)
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{
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void* p = pglMapBufferARB(m_Target, GL_WRITE_ONLY);
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if (p == NULL)
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{
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// This shouldn't happen unless we run out of virtual address space
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LOGERROR("glMapBuffer failed");
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break;
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}
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#ifndef NDEBUG
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// To help detect bugs where PrepareForRendering() was not called,
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// force all not-needed data to 0, so things won't get rendered
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// with undefined (but possibly still correct-looking) data.
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memset(p, 0, m_MaxVertices * m_VertexSize);
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#endif
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// Copy only the chunks we need. (This condition is helpful when
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// the VBO contains data for every unit in the world, but only a
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// handful are visible on screen and we don't need to bother copying
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// the rest.)
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for (VBChunk* const& chunk : m_AllocList)
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if (chunk->m_Needed)
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memcpy((u8 *)p + chunk->m_Index * m_VertexSize, chunk->m_BackingStore, chunk->m_Count * m_VertexSize);
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if (pglUnmapBufferARB(m_Target) == GL_TRUE)
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break;
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// Unmap might fail on e.g. resolution switches, so just try again
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// and hope it will eventually succeed
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debug_printf("glUnmapBuffer failed, trying again...\n");
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}
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// Anything we just uploaded is clean; anything else is dirty
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// since the rest of the VBO content is now undefined
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for (VBChunk* const& chunk : m_AllocList)
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{
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if (chunk->m_Needed)
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chunk->m_Dirty = false;
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else
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chunk->m_Dirty = true;
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}
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}
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// Reset the flags for the next phase
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for (VBChunk* const& chunk : m_AllocList)
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chunk->m_Needed = false;
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}
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return (u8*)0;
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}
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u8* CVertexBuffer::GetBindAddress()
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{
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if (g_Renderer.m_Caps.m_VBO)
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return (u8*)0;
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else
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return m_SysMem;
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}
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void CVertexBuffer::Unbind()
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{
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if (g_Renderer.m_Caps.m_VBO)
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{
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pglBindBufferARB(GL_ARRAY_BUFFER, 0);
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pglBindBufferARB(GL_ELEMENT_ARRAY_BUFFER, 0);
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}
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}
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size_t CVertexBuffer::GetBytesReserved() const
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{
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return MAX_VB_SIZE_BYTES;
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}
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size_t CVertexBuffer::GetBytesAllocated() const
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{
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return (m_MaxVertices - m_FreeVertices) * m_VertexSize;
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}
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void CVertexBuffer::DumpStatus()
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{
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debug_printf("freeverts = %d\n", (int)m_FreeVertices);
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size_t maxSize = 0;
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typedef std::list<VBChunk*>::iterator Iter;
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for (Iter iter = m_FreeList.begin(); iter != m_FreeList.end(); ++iter)
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{
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debug_printf("free chunk %p: size=%d\n", (void *)*iter, (int)((*iter)->m_Count));
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maxSize = std::max((*iter)->m_Count, maxSize);
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}
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debug_printf("max size = %d\n", (int)maxSize);
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}
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bool CVertexBuffer::UseStreaming(GLenum usage)
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{
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return (usage == GL_DYNAMIC_DRAW || usage == GL_STREAM_DRAW);
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}
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