dolphin/Source/Core/VideoBackends/OGL/BoundingBox.cpp
Stenzek 89e54fbd6c OGL: Work around slowdown of glMapBufferRange with SSBO on NVIDIA drivers
Using glMapBufferRange to read back the contents of the SSBO is extremely
slow on NVIDIA drivers. This is more noticeable at higher internal
resolutions. Using glGetBufferSubData instead does not seem to exhibit
this slowdown.
2016-05-19 21:24:09 +10:00

70 lines
1.9 KiB
C++

// Copyright 2014 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#include "Common/GL/GLUtil.h"
#include "VideoBackends/OGL/BoundingBox.h"
#include "VideoCommon/DriverDetails.h"
#include "VideoCommon/VideoConfig.h"
static GLuint s_bbox_buffer_id;
namespace OGL
{
void BoundingBox::Init()
{
if (g_ActiveConfig.backend_info.bSupportsBBox)
{
int initial_values[4] = {0,0,0,0};
glGenBuffers(1, &s_bbox_buffer_id);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, s_bbox_buffer_id);
glBufferData(GL_SHADER_STORAGE_BUFFER, 4 * sizeof(s32), initial_values, GL_DYNAMIC_DRAW);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, s_bbox_buffer_id);
}
}
void BoundingBox::Shutdown()
{
if (g_ActiveConfig.backend_info.bSupportsBBox)
glDeleteBuffers(1, &s_bbox_buffer_id);
}
void BoundingBox::Set(int index, int value)
{
glBindBuffer(GL_SHADER_STORAGE_BUFFER, s_bbox_buffer_id);
glBufferSubData(GL_SHADER_STORAGE_BUFFER, index * sizeof(int), sizeof(int), &value);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, 0);
}
int BoundingBox::Get(int index)
{
int data = 0;
glBindBuffer(GL_SHADER_STORAGE_BUFFER, s_bbox_buffer_id);
if (!DriverDetails::HasBug(DriverDetails::BUG_SLOWGETBUFFERSUBDATA))
{
// Using glMapBufferRange to read back the contents of the SSBO is extremely slow
// on nVidia drivers. This is more noticeable at higher internal resolutions.
// Using glGetBufferSubData instead does not seem to exhibit this slowdown.
glGetBufferSubData(GL_SHADER_STORAGE_BUFFER, index * sizeof(int), sizeof(int), &data);
}
else
{
// Using glMapBufferRange is faster on AMD cards by a measurable margin.
void* ptr = glMapBufferRange(GL_SHADER_STORAGE_BUFFER, index * sizeof(int), sizeof(int), GL_MAP_READ_BIT);
if (ptr)
{
memcpy(&data, ptr, sizeof(int));
glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
}
}
glBindBuffer(GL_SHADER_STORAGE_BUFFER, 0);
return data;
}
};