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// OpenCSG - library for image-based CSG rendering for OpenGL
// Copyright (C) 2002-2022, Florian Kirsch,
// Hasso-Plattner-Institute at the University of Potsdam, Germany
//
// This library 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; either version 2 of the License, or
// (at your option) any later version.
//
// This library 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 for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110 - 1301 USA.
//
// stencilManager.cpp
//
#include "opencsgConfig.h"
#include <GL/glew.h>
#ifdef _WIN32
#include <GL/wglew.h>
#elif !defined(__APPLE__)
#include <GL/glxew.h>
#endif
#include "area.h"
#include "openglHelper.h"
#include "stencilManager.h"
#include <vector>
namespace OpenCSG {
namespace OpenGL {
StencilManager::StencilManager(const PCArea& area) : mArea(area), mSaved(false) {}
// Do not save the stencil buffer at all.
// This is, currently, used always.
StencilManager::~StencilManager() { }
const PCArea& StencilManager::getArea() const {
return mArea;
}
void StencilManager::clear() {
if (!mSaved) {
save();
mSaved = true;
}
glStencilMask(OpenGL::stencilMask);
glClear(GL_STENCIL_BUFFER_BIT);
}
bool StencilManager::alreadySaved() const {
return mSaved;
}
void StencilManager::save() {
// implemented empty. will not save the stencil buffer
}
void StencilManager::restore() {
// implemented empty. will not restore the stencil buffer
}
class StencilManagerGL10 : public StencilManager {
public:
StencilManagerGL10(const PCArea& area) : StencilManager(area) {};
// Saves and restores the stencil buffer by copying it from
// graphics memory to main memory and back.
// Warning: There appears to be a bug in this implementation.
// Saving and restoring does not work at all.
virtual void save();
virtual void restore();
};
namespace {
std::vector<GLubyte>* buf = 0;
int dx, dy;
}
void StencilManagerGL10::save() {
const PCArea& area = getArea();
dx = area.maxx - area.minx;
dy = area.maxy - area.miny;
unsigned int size = (8+dx)*dy; // 8 needed due to possible alignment (?)
if (!buf) {
buf = new std::vector<GLubyte>(size);
} else if (buf->size() < size) {
buf->resize(size);
}
glReadPixels(area.minx, area.miny, dx, dy, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &((*buf)[0]));
}
void StencilManagerGL10::restore() {
if (!alreadySaved()) return; // stencil buffer was never changed, restore nothing
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
glRasterPos2i(-1, -1);
glDrawPixels(dx, dy, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, &((*buf)[0]));
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
}
#ifdef _WIN32
class StencilManagerARBBufferRegionW32 : public StencilManager {
public:
StencilManagerARBBufferRegionW32(const PCArea& area) : StencilManager(area) {};
// Uses the ARB_buffer_region extension for saving and restoring the
// stencil buffer. If this extension is available, this works well
// and is reasonably fast.
virtual void save();
virtual void restore();
private:
HDC hdc;
HANDLE handle;
};
void StencilManagerARBBufferRegionW32::save() {
const PCArea& area = getArea();
dx = area.maxx - area.minx;
dy = area.maxy - area.miny;
hdc = wglGetCurrentDC();
handle = wglCreateBufferRegionARB(hdc, 1, WGL_STENCIL_BUFFER_BIT_ARB);
if (handle == 0) {
return;
}
int result = wglSaveBufferRegionARB(handle, area.minx, area.miny, dx, dy);
}
void StencilManagerARBBufferRegionW32::restore() {
if (!alreadySaved()) return; // stencil buffer was never changed, restore nothing
const PCArea& area = getArea();
dx = area.maxx - area.minx;
dy = area.maxy - area.miny;
wglRestoreBufferRegionARB(handle, area.minx, area.miny, dx, dy, 0, 0);
wglDeleteBufferRegionARB(handle);
}
#endif // _WIN32
StencilManager* getStencilManager(const PCArea& area) {
#ifdef _WIN32
/*
// uncomment for possibility of saving the stencil buffer under windows
if (WGLEW_ARB_buffer_region) {
return new StencilManagerARBBufferRegionW32(area);
}
*/
#endif // _WIN32
/*
// this option has a bug unfortunately and is not usable
return new StencilManagerGL10(area);
*/
return new StencilManager(area);
}
} // namespace OpenGL
} // namespace OpenCSG
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