axmol/cocos/2d/CCClippingNode.cpp

/*
 * cocos2d for iPhone: http://www.cocos2d-iphone.org
 * cocos2d-x: http://www.cocos2d-x.org
 *
 * Copyright (c) 2012 Pierre-David Bélanger
 * Copyright (c) 2012 cocos2d-x.org
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

#include "CCClippingNode.h"
#include "kazmath/GL/matrix.h"
#include "CCGLProgram.h"
#include "CCShaderCache.h"
#include "CCDirector.h"
#include "CCDrawingPrimitives.h"
#include "CCRenderer.h"
#include "CCGroupCommand.h"
#include "CCCustomCommand.h"

NS_CC_BEGIN

static GLint g_sStencilBits = -1;
// store the current stencil layer (position in the stencil buffer),
// this will allow nesting up to n ClippingNode,
// where n is the number of bits of the stencil buffer.
static GLint s_layer = -1;

static void setProgram(Node *n, GLProgram *p)
{
    n->setShaderProgram(p);
    
    auto& children = n->getChildren();
    for(const auto &child : children) {
        setProgram(child, p);
    }
}

ClippingNode::ClippingNode()
: _stencil(nullptr)
, _alphaThreshold(0.0f)
, _inverted(false)
, _currentStencilEnabled(GL_FALSE)
, _currentStencilWriteMask(~0)
, _currentStencilFunc(GL_ALWAYS)
, _currentStencilRef(0)
, _currentStencilValueMask(~0)
, _currentStencilFail(GL_KEEP)
, _currentStencilPassDepthFail(GL_KEEP)
, _currentStencilPassDepthPass(GL_KEEP)
, _currentDepthWriteMask(GL_TRUE)
,  _currentAlphaTestEnabled(GL_FALSE)
, _currentAlphaTestFunc(GL_ALWAYS)
, _currentAlphaTestRef(1)
{

}

ClippingNode::~ClippingNode()
{
    CC_SAFE_RELEASE(_stencil);
}

ClippingNode* ClippingNode::create()
{
    ClippingNode *ret = new ClippingNode();
    if (ret && ret->init())
    {
        ret->autorelease();
    }
    else
    {
        CC_SAFE_DELETE(ret);
    }
    
    return ret;
}

ClippingNode* ClippingNode::create(Node *pStencil)
{
    ClippingNode *ret = new ClippingNode();
    if (ret && ret->init(pStencil))
    {
        ret->autorelease();
    }
    else
    {
        CC_SAFE_DELETE(ret);
    }
    
    return ret;
}

bool ClippingNode::init()
{
    return init(nullptr);
}

bool ClippingNode::init(Node *stencil)
{
    CC_SAFE_RELEASE(_stencil);
    _stencil = stencil;
    CC_SAFE_RETAIN(_stencil);
    
    _alphaThreshold = 1;
    _inverted = false;
    // get (only once) the number of bits of the stencil buffer
    static bool once = true;
    if (once)
    {
        glGetIntegerv(GL_STENCIL_BITS, &g_sStencilBits);
        if (g_sStencilBits <= 0)
        {
            CCLOG("Stencil buffer is not enabled.");
        }
        once = false;
    }
    
    return true;
}

void ClippingNode::onEnter()
{
    Node::onEnter();
    
    if (_stencil != nullptr)
    {
        _stencil->onEnter();
    }
    else
    {
        CCLOG("ClippingNode warning: _stencil is nil.");
    }
}

void ClippingNode::onEnterTransitionDidFinish()
{
    Node::onEnterTransitionDidFinish();
    
    if (_stencil != nullptr)
    {
        _stencil->onEnterTransitionDidFinish();
    }
}

void ClippingNode::onExitTransitionDidStart()
{
    if (_stencil != nullptr)
    {
        _stencil->onExitTransitionDidStart();
    }
   
    Node::onExitTransitionDidStart();
}

void ClippingNode::onExit()
{
    if (_stencil != nullptr)
    {
        _stencil->onExit();
    }
    
    Node::onExit();
}

void ClippingNode::drawFullScreenQuadClearStencil()
{
    kmGLMatrixMode(KM_GL_MODELVIEW);
    kmGLPushMatrix();
    kmGLLoadIdentity();
    
    kmGLMatrixMode(KM_GL_PROJECTION);
    kmGLPushMatrix();
    kmGLLoadIdentity();
    
    DrawPrimitives::drawSolidRect(Point(-1,-1), Point(1,1), Color4F(1, 1, 1, 1));
    
    kmGLMatrixMode(KM_GL_PROJECTION);
    kmGLPopMatrix();
    kmGLMatrixMode(KM_GL_MODELVIEW);
    kmGLPopMatrix();
}

void ClippingNode::visit()
{
    if(!_visible)
        return;
    
    kmGLPushMatrix();
    transform();
    //Add group command
    
    Renderer* renderer = Director::getInstance()->getRenderer();
    
    GroupCommand* groupCommand = GroupCommand::getCommandPool().generateCommand();
    groupCommand->init(0,_vertexZ);
    renderer->addCommand(groupCommand);

    renderer->pushGroup(groupCommand->getRenderQueueID());

    CustomCommand* beforeVisitCmd = CustomCommand::getCommandPool().generateCommand();
    beforeVisitCmd->init(0,_vertexZ);
    beforeVisitCmd->func = CC_CALLBACK_0(ClippingNode::onBeforeVisit, this);
    renderer->addCommand(beforeVisitCmd);

    _stencil->visit();

    CustomCommand* afterDrawStencilCmd = CustomCommand::getCommandPool().generateCommand();
    afterDrawStencilCmd->init(0,_vertexZ);
    afterDrawStencilCmd->func = CC_CALLBACK_0(ClippingNode::onAfterDrawStencil, this);
    renderer->addCommand(afterDrawStencilCmd);

    int i = 0;
    
    if(!_children.empty())
    {
        sortAllChildren();
        // draw children zOrder < 0
        for( ; i < _children.size(); i++ )
        {
            auto node = _children.at(i);
            
            if ( node && node->getZOrder() < 0 )
                node->visit();
            else
                break;
        }
        // self draw
        this->draw();
        
        for(auto it=_children.cbegin()+i; it != _children.cend(); ++it)
            (*it)->visit();
    }
    else
    {
        this->draw();
    }

    CustomCommand* afterVisitCmd = CustomCommand::getCommandPool().generateCommand();
    afterVisitCmd->init(0,_vertexZ);
    afterVisitCmd->func = CC_CALLBACK_0(ClippingNode::onAfterVisit, this);
    renderer->addCommand(afterVisitCmd);

    renderer->popGroup();
    
    kmGLPopMatrix();
}

Node* ClippingNode::getStencil() const
{
    return _stencil;
}

void ClippingNode::setStencil(Node *stencil)
{
    CC_SAFE_RELEASE(_stencil);
    _stencil = stencil;
    CC_SAFE_RETAIN(_stencil);
}

GLfloat ClippingNode::getAlphaThreshold() const
{
    return _alphaThreshold;
}

void ClippingNode::setAlphaThreshold(GLfloat alphaThreshold)
{
    _alphaThreshold = alphaThreshold;
}

bool ClippingNode::isInverted() const
{
    return _inverted;
}

void ClippingNode::setInverted(bool inverted)
{
    _inverted = inverted;
}

void ClippingNode::onBeforeVisit()
{
    ///////////////////////////////////
    // INIT

    // increment the current layer
    s_layer++;

    // mask of the current layer (ie: for layer 3: 00000100)
    GLint mask_layer = 0x1 << s_layer;
    // mask of all layers less than the current (ie: for layer 3: 00000011)
    GLint mask_layer_l = mask_layer - 1;
    // mask of all layers less than or equal to the current (ie: for layer 3: 00000111)
    _mask_layer_le = mask_layer | mask_layer_l;

    // manually save the stencil state

    _currentStencilEnabled = glIsEnabled(GL_STENCIL_TEST);
    glGetIntegerv(GL_STENCIL_WRITEMASK, (GLint *)&_currentStencilWriteMask);
    glGetIntegerv(GL_STENCIL_FUNC, (GLint *)&_currentStencilFunc);
    glGetIntegerv(GL_STENCIL_REF, &_currentStencilRef);
    glGetIntegerv(GL_STENCIL_VALUE_MASK, (GLint *)&_currentStencilValueMask);
    glGetIntegerv(GL_STENCIL_FAIL, (GLint *)&_currentStencilFail);
    glGetIntegerv(GL_STENCIL_PASS_DEPTH_FAIL, (GLint *)&_currentStencilPassDepthFail);
    glGetIntegerv(GL_STENCIL_PASS_DEPTH_PASS, (GLint *)&_currentStencilPassDepthPass);

    // enable stencil use
    glEnable(GL_STENCIL_TEST);
    // check for OpenGL error while enabling stencil test
    CHECK_GL_ERROR_DEBUG();

    // all bits on the stencil buffer are readonly, except the current layer bit,
    // this means that operation like glClear or glStencilOp will be masked with this value
    glStencilMask(mask_layer);

    // manually save the depth test state

    glGetBooleanv(GL_DEPTH_WRITEMASK, &_currentDepthWriteMask);

    // disable depth test while drawing the stencil
    //glDisable(GL_DEPTH_TEST);
    // disable update to the depth buffer while drawing the stencil,
    // as the stencil is not meant to be rendered in the real scene,
    // it should never prevent something else to be drawn,
    // only disabling depth buffer update should do
    glDepthMask(GL_FALSE);

    ///////////////////////////////////
    // CLEAR STENCIL BUFFER

    // manually clear the stencil buffer by drawing a fullscreen rectangle on it
    // setup the stencil test func like this:
    // for each pixel in the fullscreen rectangle
    //     never draw it into the frame buffer
    //     if not in inverted mode: set the current layer value to 0 in the stencil buffer
    //     if in inverted mode: set the current layer value to 1 in the stencil buffer
    glStencilFunc(GL_NEVER, mask_layer, mask_layer);
    glStencilOp(!_inverted ? GL_ZERO : GL_REPLACE, GL_KEEP, GL_KEEP);

    // draw a fullscreen solid rectangle to clear the stencil buffer
    //ccDrawSolidRect(Point::ZERO, ccpFromSize([[Director sharedDirector] winSize]), Color4F(1, 1, 1, 1));
    drawFullScreenQuadClearStencil();

    ///////////////////////////////////
    // DRAW CLIPPING STENCIL

    // setup the stencil test func like this:
    // for each pixel in the stencil node
    //     never draw it into the frame buffer
    //     if not in inverted mode: set the current layer value to 1 in the stencil buffer
    //     if in inverted mode: set the current layer value to 0 in the stencil buffer
    glStencilFunc(GL_NEVER, mask_layer, mask_layer);
    glStencilOp(!_inverted ? GL_REPLACE : GL_ZERO, GL_KEEP, GL_KEEP);

    // enable alpha test only if the alpha threshold < 1,
    // indeed if alpha threshold == 1, every pixel will be drawn anyways
    if (_alphaThreshold < 1) {
#if (CC_TARGET_PLATFORM == CC_PLATFORM_MAC || CC_TARGET_PLATFORM == CC_PLATFORM_WINDOWS || CC_TARGET_PLATFORM == CC_PLATFORM_LINUX)
        // manually save the alpha test state
        _currentAlphaTestEnabled = glIsEnabled(GL_ALPHA_TEST);
        glGetIntegerv(GL_ALPHA_TEST_FUNC, (GLint *)&_currentAlphaTestFunc);
        glGetFloatv(GL_ALPHA_TEST_REF, &_currentAlphaTestRef);
        // enable alpha testing
        glEnable(GL_ALPHA_TEST);
        // check for OpenGL error while enabling alpha test
        CHECK_GL_ERROR_DEBUG();
        // pixel will be drawn only if greater than an alpha threshold
        glAlphaFunc(GL_GREATER, _alphaThreshold);
#else
        // since glAlphaTest do not exists in OES, use a shader that writes
        // pixel only if greater than an alpha threshold
        GLProgram *program = ShaderCache::getInstance()->getProgram(GLProgram::SHADER_NAME_POSITION_TEXTURE_ALPHA_TEST);
        GLint alphaValueLocation = glGetUniformLocation(program->getProgram(), GLProgram::UNIFORM_NAME_ALPHA_TEST_VALUE);
        // set our alphaThreshold
        program->use();
        program->setUniformLocationWith1f(alphaValueLocation, _alphaThreshold);
        // we need to recursively apply this shader to all the nodes in the stencil node
        // XXX: we should have a way to apply shader to all nodes without having to do this
        setProgram(_stencil, program);

#endif
    }

    //Draw _stencil
}

void ClippingNode::onAfterDrawStencil()
{
    // restore alpha test state
    if (_alphaThreshold < 1)
    {
#if (CC_TARGET_PLATFORM == CC_PLATFORM_MAC || CC_TARGET_PLATFORM == CC_PLATFORM_WINDOWS || CC_TARGET_PLATFORM == CC_PLATFORM_LINUX)
        // manually restore the alpha test state
        glAlphaFunc(_currentAlphaTestFunc, _currentAlphaTestRef);
        if (!_currentAlphaTestEnabled)
        {
            glDisable(GL_ALPHA_TEST);
        }
#else
// XXX: we need to find a way to restore the shaders of the stencil node and its childs
#endif
    }

    // restore the depth test state
    glDepthMask(_currentDepthWriteMask);
    //if (currentDepthTestEnabled) {
    //    glEnable(GL_DEPTH_TEST);
    //}

    ///////////////////////////////////
    // DRAW CONTENT

    // setup the stencil test func like this:
    // for each pixel of this node and its childs
    //     if all layers less than or equals to the current are set to 1 in the stencil buffer
    //         draw the pixel and keep the current layer in the stencil buffer
    //     else
    //         do not draw the pixel but keep the current layer in the stencil buffer
    glStencilFunc(GL_EQUAL, _mask_layer_le, _mask_layer_le);
    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);

    // draw (according to the stencil test func) this node and its childs
}


void ClippingNode::onAfterVisit()
{
    ///////////////////////////////////
    // CLEANUP

    // manually restore the stencil state
    glStencilFunc(_currentStencilFunc, _currentStencilRef, _currentStencilValueMask);
    glStencilOp(_currentStencilFail, _currentStencilPassDepthFail, _currentStencilPassDepthPass);
    glStencilMask(_currentStencilWriteMask);
    if (!_currentStencilEnabled)
    {
        glDisable(GL_STENCIL_TEST);
    }

    // we are done using this layer, decrement
    s_layer--;
}

NS_CC_END