axmol/cocos/base/CCStencilStateManager.cpp

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 Copyright (c) 2013-2016 Chukong Technologies Inc.
 Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.
 
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#include "base/CCStencilStateManager.h"
#include "base/CCDirector.h"
#include "renderer/CCGLProgramCache.h"
#include "renderer/CCRenderer.h"
#include "renderer/CCRenderState.h"
#if (CC_TARGET_PLATFORM == CC_PLATFORM_MAC || CC_TARGET_PLATFORM == CC_PLATFORM_WIN32 || CC_TARGET_PLATFORM == CC_PLATFORM_LINUX)
#define CC_CLIPPING_NODE_OPENGLES 0
#else
#define CC_CLIPPING_NODE_OPENGLES 1
#endif

NS_CC_BEGIN

GLint StencilStateManager::s_layer = -1;

StencilStateManager::StencilStateManager()
: _alphaThreshold(1.0f)
, _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)

{
}

void StencilStateManager::drawFullScreenQuadClearStencil()
{
    Director* director = Director::getInstance();
    CCASSERT(nullptr != director, "Director is null when setting matrix stack");
    
    director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
    director->loadIdentityMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
    
    director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION);
    director->loadIdentityMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION);
    
    Vec2 vertices[] = {
        Vec2(-1.0f, -1.0f),
        Vec2(1.0f, -1.0f),
        Vec2(1.0f, 1.0f),
        Vec2(-1.0f, 1.0f)
    };
    
    auto glProgram = GLProgramCache::getInstance()->getGLProgram(GLProgram::SHADER_NAME_POSITION_U_COLOR);
    
    int colorLocation = glProgram->getUniformLocation("u_color");
    CHECK_GL_ERROR_DEBUG();
    
    Color4F color(1, 1, 1, 1);
    
    glProgram->use();
    glProgram->setUniformsForBuiltins();
    glProgram->setUniformLocationWith4fv(colorLocation, (GLfloat*) &color.r, 1);
    
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glEnableVertexAttribArray(GLProgram::VERTEX_ATTRIB_POSITION);
    glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);
    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
    
    CC_INCREMENT_GL_DRAWN_BATCHES_AND_VERTICES(1, 4);
    
    director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION);
    director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
}


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

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

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

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

void StencilStateManager::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);
    //    RenderState::StateBlock::_defaultState->setStencilTest(true);
    
    // 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);
    //    RenderState::StateBlock::_defaultState->setStencilWrite(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);
    RenderState::StateBlock::_defaultState->setDepthWrite(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(Vec2::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);
    //    RenderState::StateBlock::_defaultState->setStencilFunction(RenderState::STENCIL_NEVER, mask_layer, mask_layer);
    
    glStencilOp(!_inverted ? GL_REPLACE : GL_ZERO, GL_KEEP, GL_KEEP);
    //    RenderState::StateBlock::_defaultState->setStencilOperation(
    //                                                                !_inverted ? RenderState::STENCIL_OP_REPLACE : RenderState::STENCIL_OP_ZERO,
    //                                                                RenderState::STENCIL_OP_KEEP,
    //                                                                RenderState::STENCIL_OP_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_CLIPPING_NODE_OPENGLES
        // 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);
#endif
    }
    
    //Draw _stencil
}

void StencilStateManager::onAfterDrawStencil()
{
    // restore alpha test state
    if (_alphaThreshold < 1)
    {
#if CC_CLIPPING_NODE_OPENGLES
        // FIXME: we need to find a way to restore the shaders of the stencil node and its children
#else
        // manually restore the alpha test state
        glAlphaFunc(_currentAlphaTestFunc, _currentAlphaTestRef);
        if (!_currentAlphaTestEnabled)
        {
            glDisable(GL_ALPHA_TEST);
        }
#endif
    }
    
    // restore the depth test state
    glDepthMask(_currentDepthWriteMask);
    RenderState::StateBlock::_defaultState->setDepthWrite(_currentDepthWriteMask != 0);
    
    //if (currentDepthTestEnabled) {
    //    glEnable(GL_DEPTH_TEST);
    //}
    
    ///////////////////////////////////
    // DRAW CONTENT
    
    // setup the stencil test function like this:
    // for each pixel of this node and its children
    //     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);
    //    RenderState::StateBlock::_defaultState->setStencilFunction(RenderState::STENCIL_EQUAL, _mask_layer_le, _mask_layer_le);
    
    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
    //    RenderState::StateBlock::_defaultState->setStencilOperation(RenderState::STENCIL_OP_KEEP, RenderState::STENCIL_OP_KEEP, RenderState::STENCIL_OP_KEEP);
    
    // draw (according to the stencil test function) this node and its children

}

void StencilStateManager::onAfterVisit()
{
    ///////////////////////////////////
    // CLEANUP
    
    // manually restore the stencil state
    glStencilFunc(_currentStencilFunc, _currentStencilRef, _currentStencilValueMask);
    //    RenderState::StateBlock::_defaultState->setStencilFunction((RenderState::StencilFunction)_currentStencilFunc, _currentStencilRef, _currentStencilValueMask);
    
    glStencilOp(_currentStencilFail, _currentStencilPassDepthFail, _currentStencilPassDepthPass);
    //    RenderState::StateBlock::_defaultState->setStencilOperation((RenderState::StencilOperation)_currentStencilFail,
    //                                                                (RenderState::StencilOperation)_currentStencilPassDepthFail,
    //                                                                (RenderState::StencilOperation)_currentStencilPassDepthPass);
    
    glStencilMask(_currentStencilWriteMask);
    if (!_currentStencilEnabled)
    {
        glDisable(GL_STENCIL_TEST);
        //        RenderState::StateBlock::_defaultState->setStencilTest(false);
    }
    
    // we are done using this layer, decrement
    s_layer--;
}


NS_CC_END