SpriteBatchNode继承Node，并实现了TextureProtocol接口，重写了Node的addChild()方法，visit()方法以及draw()方法。
addChild()方法限制其子元素只能是Sprite，
并且子元素与SpriteBatchNode必须使用同一个Texture2D对象。
visit()用于阻止元素向下遍历，将所有子元素的绘制工作交给自己处理。
draw()方法使用BatchNodeCommand将绘制命令发送到RenderQueue，从而对所有子元素进行批绘制。
SpriteBatchNode使用TextureAtlas存储所有子精灵的顶点信息。TextureAtlas包含一个V3F_C4B_T2F_Quad数组和一个Texture2D对象，提供对quads数组的添加，删除，修改，排序等功能。这样，SpriteBatchNode所做的主要事情就是将与子元素相关的顶点信息存储到TextureAtlas中。最后，TextureAtlas提供了绘制quads的方法，
BatchCommand就是通过drawQuads()方法绘制的
代码流程：
1 调用
auto spBatchNode = SpriteBatchNode::create("bbb.png");
spBatchNode->setPosition(Point::ZERO);
scene->addChild(spBatchNode);
spBatchNode->setPosition(,);
// spBatchNode->setScale(0.1);
auto sp = Sprite::createWithTexture(spBatchNode->getTexture());
sp->setPosition(,);
spBatchNode->addChild(sp,);
sp = Sprite::createWithTexture(spBatchNode->getTexture());
sp->setPosition(,);
spBatchNode->addChild(sp,-);
2 看一下SpriteBatchNode内部方法
初始化方法
bool SpriteBatchNode::initWithTexture(Texture2D *tex, ssize_t capacity)
{
CCASSERT(capacity>=, "Capacity must be >= 0"); _blendFunc = BlendFunc::ALPHA_PREMULTIPLIED; if(tex->hasPremultipliedAlpha())//alpha预乘，忽略
{
_blendFunc = BlendFunc::ALPHA_NON_PREMULTIPLIED;
} //使用textureAtlas存储所有子精灵的顶点信息，通过对quads数组的添加，删除，修改排序等
_textureAtlas = new TextureAtlas(); if (capacity == )
{
capacity = DEFAULT_CAPACITY;
} _textureAtlas->initWithTexture(tex, capacity); updateBlendFunc(); _children.reserve(capacity);
//分配空间大小
_descendants.reserve(capacity);
//定义属于自己的着色器
setGLProgramState(GLProgramState::getOrCreateWithGLProgramName(GLProgram::SHADER_NAME_POSITION_TEXTURE_COLOR));
return true;
}
添加子元素方法：
void SpriteBatchNode::addChild(Node * child, int zOrder, const std::string &name)
{
CCASSERT(child != nullptr, "child should not be null");
CCASSERT(dynamic_cast<Sprite*>(child) != nullptr, "CCSpriteBatchNode only supports Sprites as children");
Sprite *sprite = static_cast<Sprite*>(child);
// check Sprite is using the same texture id
CCASSERT(sprite->getTexture()->getName() == _textureAtlas->getTexture()->getName(), "CCSprite is not using the same texture id"); Node::addChild(child, zOrder, name); appendChild(sprite);
}
// addChild helper, faster than insertChild
void SpriteBatchNode::appendChild(Sprite* sprite)
{
_reorderChildDirty=true;
sprite->setBatchNode(this);
sprite->setDirty(true); if(_textureAtlas->getTotalQuads() == _textureAtlas->getCapacity()) {
increaseAtlasCapacity();//重新调整容器大小，
} _descendants.push_back(sprite);//所有的子节点。
int index = static_cast<int>(_descendants.size()-); sprite->setAtlasIndex(index);//设置sprite的渲染节点为TextureAtlas的第index个数据 V3F_C4B_T2F_Quad quad = sprite->getQuad();
//把新sprite的顶点信息放到textureAtlas，供绘制使用，此时的顶点坐标还是在父亲中的坐标，不是世界坐标
_textureAtlas->insertQuad(&quad, index);//将sprite的顶点数据传入到TextureAtlas的index位置。 // add children recursively
auto& children = sprite->getChildren();
for(const auto &child: children) { //递归调用
appendChild(static_cast<Sprite*>(child)); //将sprite的所有数据加入到descendants。
}
}
遍历方法visit
// override visit
// don't call visit on it's children
void SpriteBatchNode::visit(Renderer *renderer, const Mat4 &parentTransform, uint32_t parentFlags)
{
CC_PROFILER_START_CATEGORY(kProfilerCategoryBatchSprite, "CCSpriteBatchNode - visit"); // CAREFUL:
// This visit is almost identical to CocosNode#visit
// with the exception that it doesn't call visit on it's children
//
// The alternative is to have a void Sprite#visit, but
// although this is less maintainable, is faster
//
if (! _visible)
{
return;
}
//排序,写的挺不错
sortAllChildren();
//得到本地坐标转换世界坐标的矩阵
uint32_t flags = processParentFlags(parentTransform, parentFlags); // IMPORTANT:
// To ease the migration to v3.0, we still support the Mat4 stack,
// but it is deprecated and your code should not rely on it
Director* director = Director::getInstance();
director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW, _modelViewTransform); draw(renderer, _modelViewTransform, flags); director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
// FIX ME: Why need to set _orderOfArrival to 0??
// Please refer to https://github.com/cocos2d/cocos2d-x/pull/6920
// setOrderOfArrival(0); CC_PROFILER_STOP_CATEGORY(kProfilerCategoryBatchSprite, "CCSpriteBatchNode - visit");
}
//override sortAllChildren
//排序功能
void SpriteBatchNode::sortAllChildren()
{
if (_reorderChildDirty)
{
std::sort(std::begin(_children), std::end(_children), nodeComparisonLess); //sorted now check all children
if (!_children.empty())
{
//first sort all children recursively based on zOrder
for(const auto &child: _children) {
child->sortAllChildren();
} ssize_t index=; //fast dispatch, give every child a new atlasIndex based on their relative zOrder (keep parent -> child relations intact)
// and at the same time reorder descendants and the quads to the right index
/*
//快速发送，根据每个孩子的相对zOrder给每个孩子一个新的atlasIndex（保持父母 - >孩子的关系不变）
//同时重新排序descendants数组和四边形到正确的索引
*/
//此时的childern为根据localZ从小到大排序之后的数组
for(const auto &child: _children) {
Sprite* sp = static_cast<Sprite*>(child);
updateAtlasIndex(sp, &index);
}
} _reorderChildDirty=false;
}
}
//更新sprite和sprite子节点的atlas数据的index。
void SpriteBatchNode::updateAtlasIndex(Sprite* sprite, ssize_t* curIndex)
{
auto& array = sprite->getChildren();
auto count = array.size(); ssize_t oldIndex = ;
/*
在sortAllChildren，根据localZ对children进行了排序，从小到大排序，因为之前的AtlasIndex为顺序赋值的，所以要重新设置AtlasIndex
*/
//如果没有子节点，那么sprite就是curIndex位置了
if( count == )
{
oldIndex = sprite->getAtlasIndex();
sprite->setAtlasIndex(*curIndex);//重新递增赋值
sprite->setOrderOfArrival(); if (oldIndex != *curIndex){
//更新在_textureAtlas等中的位置
swap(oldIndex, *curIndex);
}
(*curIndex)++;
}
else
{
bool needNewIndex=true;//是否需要赋值新的索引
//先localZ<0的，然后sprite,最后localZ>0
//因为先对所有的子节点排序过。先localZ<0，然后localZ>0 //如果第一个localZ>=0那么先设置sprite的index
if (array.at()->getLocalZOrder() >= )
{
//sprite的第一个孩子local都大于0，剩下的孩子都大于0，所以孩子绘制都在自己上面
//all children are in front of the parent
oldIndex = sprite->getAtlasIndex();
sprite->setAtlasIndex(*curIndex);
sprite->setOrderOfArrival();
if (oldIndex != *curIndex)
{
swap(oldIndex, *curIndex);
}
(*curIndex)++; needNewIndex = false;//不需要新的索引，后面的按照顺序遍历就行
} for(const auto &child: array) {
Sprite* sp = static_cast<Sprite*>(child);
//找到了第一个localZorder>0的，设置sprite。
if (needNewIndex && sp->getLocalZOrder() >= )
{
oldIndex = sprite->getAtlasIndex();
sprite->setAtlasIndex(*curIndex);
sprite->setOrderOfArrival();
if (oldIndex != *curIndex) {
this->swap(oldIndex, *curIndex);
}
(*curIndex)++;
needNewIndex = false;
}
//递归调用
updateAtlasIndex(sp, curIndex);
} //这种情况是：所有的子节点都是localZ<0。
//all children have a zOrder < 0)
/*
sprite的children已经遍历完成，最后轮到sprite自己
*/
if (needNewIndex)
{
oldIndex = sprite->getAtlasIndex();
sprite->setAtlasIndex(*curIndex);
sprite->setOrderOfArrival();
if (oldIndex != *curIndex) {
swap(oldIndex, *curIndex);
}
(*curIndex)++;
}
}
}
swap把新排序的顶点数据更新到 quads中，用于为opengl提供基础数据
void SpriteBatchNode::swap(ssize_t oldIndex, ssize_t newIndex)
{
CCASSERT(oldIndex>= && oldIndex < (int)_descendants.size() && newIndex >= && newIndex < (int)_descendants.size(), "Invalid index"); V3F_C4B_T2F_Quad* quads = _textureAtlas->getQuads();
std::swap( quads[oldIndex], quads[newIndex] ); //update the index of other swapped item auto oldIt = std::next( _descendants.begin(), oldIndex );
auto newIt = std::next( _descendants.begin(), newIndex ); (*newIt)->setAtlasIndex(oldIndex);
// (*oldIt)->setAtlasIndex(newIndex); std::swap( *oldIt, *newIt );
}
重新的元素draw方法，并不是真的绘制，而是把绘制命令放到了_batchCommand中
void SpriteBatchNode::draw(Renderer *renderer, const Mat4 &transform, uint32_t flags)
{
// Optimization: Fast Dispatch
if( _textureAtlas->getTotalQuads() == )
{
return;
} for(const auto &child: _children)
{ //更新孩子的坐标，递归
child->updateTransform();
} _batchCommand.init(
_globalZOrder,
getGLProgram(),
_blendFunc,
_textureAtlas,
transform);
renderer->addCommand(&_batchCommand);
}
void Sprite::updateTransform(void)
{
CCASSERT(_batchNode, "updateTransform is only valid when Sprite is being rendered using an SpriteBatchNode"); // recalculate matrix only if it is dirty
if( isDirty() ) { // If it is not visible, or one of its ancestors is not visible, then do nothing:
if( !_visible || ( _parent && _parent != _batchNode && static_cast<Sprite*>(_parent)->_shouldBeHidden) )
{
_quad.br.vertices = _quad.tl.vertices = _quad.tr.vertices = _quad.bl.vertices = Vec3(,,);
_shouldBeHidden = true;
}
else
{
_shouldBeHidden = false;
//如果直接事batchNode的第一子元素，那么直接getNodeToParentTransform
if( ! _parent || _parent == _batchNode )
{
//得到子坐标转换父亲坐标的矩阵
_transformToBatch = getNodeToParentTransform();
}
else //如果是batchNode的孙子或者往后，那么要下面这么做，孙子乘以transformToBatch得到在batch中的坐标
{
CCASSERT( dynamic_cast<Sprite*>(_parent), "Logic error in Sprite. Parent must be a Sprite");
const Mat4 &nodeToParent = getNodeToParentTransform(); Mat4 &parentTransform = static_cast<Sprite*>(_parent)->_transformToBatch;
_transformToBatch = parentTransform * nodeToParent;
} //
// calculate the Quad based on the Affine Matrix
// Size &size = _rect.size; float x1 = _offsetPosition.x;
float y1 = _offsetPosition.y; float x2 = x1 + size.width;
float y2 = y1 + size.height; /*
_transformToBatch 为 本地坐标转父亲坐标的旋转矩阵。这个矩阵乘以sprite的
[x,y,z,1],得到sprite在Batch中的的坐标 */
float x = _transformToBatch.m[];
float y = _transformToBatch.m[]; float cr = _transformToBatch.m[];
float sr = _transformToBatch.m[];
float cr2 = _transformToBatch.m[];
float sr2 = -_transformToBatch.m[]; float ax = x1 * cr - y1 * sr2 + x;
float ay = x1 * sr + y1 * cr2 + y; float bx = x2 * cr - y1 * sr2 + x;
float by = x2 * sr + y1 * cr2 + y; float cx = x2 * cr - y2 * sr2 + x;
float cy = x2 * sr + y2 * cr2 + y; float dx = x1 * cr - y2 * sr2 + x;
float dy = x1 * sr + y2 * cr2 + y; _quad.bl.vertices = Vec3( RENDER_IN_SUBPIXEL(ax), RENDER_IN_SUBPIXEL(ay), _positionZ );
_quad.br.vertices = Vec3( RENDER_IN_SUBPIXEL(bx), RENDER_IN_SUBPIXEL(by), _positionZ );
_quad.tl.vertices = Vec3( RENDER_IN_SUBPIXEL(dx), RENDER_IN_SUBPIXEL(dy), _positionZ );
_quad.tr.vertices = Vec3( RENDER_IN_SUBPIXEL(cx), RENDER_IN_SUBPIXEL(cy), _positionZ );
} // MARMALADE CHANGE: ADDED CHECK FOR nullptr, TO PERMIT SPRITES WITH NO BATCH NODE / TEXTURE ATLAS
//把更新的四边形保存到 内存中,此时四边形的四个顶点坐标为在Batch中的坐标，不是世界坐标
if (_textureAtlas)
{
_textureAtlas->updateQuad(&_quad, _atlasIndex);
} _recursiveDirty = false;
setDirty(false);
} // MARMALADE CHANGED
// recursively iterate over children
/* if( _hasChildren )
{
// MARMALADE: CHANGED TO USE Node*
// NOTE THAT WE HAVE ALSO DEFINED virtual Node::updateTransform()
arrayMakeObjectsPerformSelector(_children, updateTransform, Sprite*);
}*/
//递归更新
Node::updateTransform();
}
3 render中执行command
void Renderer::visitRenderQueue(const RenderQueue& queue)
{
ssize_t size = queue.size(); for (ssize_t index = ; index < size; ++index)
{
auto command = queue[index];
auto commandType = command->getType();
if(RenderCommand::Type::BATCH_COMMAND == commandType)
{
flush();
auto cmd = static_cast<BatchCommand*>(command);
cmd->execute();
}
else
{
CCLOGERROR("Unknown commands in renderQueue");
}
}
}
4 RenderCommand 内执行execute
void BatchCommand::execute()
{
// Set material
_shader->use(); _shader->setUniformsForBuiltins(_mv);//_mv为模型矩阵，本地坐标乘以mv，得到世界坐标 glActiveTexture(GL_TEXTURE0 + );//0号纹理单元
//将一个纹理对象设置为当前纹理对象，同时她会指派给当前激活了的纹理单元
GL::bindTexture2D(_textureID);
GL::blendFunc(_blendType.src, _blendType.dst);//颜色混合 if ( _textureAtlas->getTexture()->getHasAlphaTexture()) {
auto loc =glGetUniformLocation(_shader->getProgram(), "CC_Texture1");
glUniform1i(loc,);
auto alpha=Director::getInstance()->getTextureCache()->addImage(_textureAtlas->getTexture()->getAlphaTexture());
glActiveTexture(GL_TEXTURE0 + );
glBindTexture(GL_TEXTURE_2D, alpha->getName());
} auto locHasAlpha=glGetUniformLocation(_shader->getProgram(),"u_hasAlpha");
glUniform1f(locHasAlpha, _textureAtlas->getTexture()->getHasAlphaTexture()?1.0f:0.0f); // Draw，开始opengl画
_textureAtlas->drawQuads();
}
5 textureAtlas执行drawQuads方法
void TextureAtlas::drawQuads()
{
this->drawNumberOfQuads(_totalQuads, );
} void TextureAtlas::drawNumberOfQuads(ssize_t numberOfQuads)
{
CCASSERT(numberOfQuads>=, "numberOfQuads must be >= 0");
this->drawNumberOfQuads(numberOfQuads, );
}
//渲染start位置的numberOfQuads的数据
void TextureAtlas::drawNumberOfQuads(ssize_t numberOfQuads, ssize_t start)
{
CCASSERT(numberOfQuads>= && start>=, "numberOfQuads and start must be >= 0"); if(!numberOfQuads)
return; GL::bindTexture2D(_texture->getName()); if (Configuration::getInstance()->supportsShareableVAO())
{
//
// Using VBO and VAO
// // XXX: update is done in draw... perhaps it should be done in a timer
if (_dirty)
{
glBindBuffer(GL_ARRAY_BUFFER, _buffersVBO[]);
// option 1: subdata
// glBufferSubData(GL_ARRAY_BUFFER, sizeof(_quads[0])*start, sizeof(_quads[0]) * n , &_quads[start] ); // option 2: data
// glBufferData(GL_ARRAY_BUFFER, sizeof(quads_[0]) * (n-start), &quads_[start], GL_DYNAMIC_DRAW); // option 3: orphaning + glMapBuffer /****************************
_quads中的顶点坐标为所有sprite在batch中的坐标，再顶点着色器中在转换为世界坐标
****************************/
glBufferData(GL_ARRAY_BUFFER, sizeof(_quads[]) * (numberOfQuads-start), nullptr, GL_DYNAMIC_DRAW);
void *buf = glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);
memcpy(buf, _quads, sizeof(_quads[])* (numberOfQuads-start));
glUnmapBuffer(GL_ARRAY_BUFFER); glBindBuffer(GL_ARRAY_BUFFER, ); _dirty = false;
} GL::bindVAO(_VAOname); #if CC_REBIND_INDICES_BUFFER
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _buffersVBO[]);
#endif glDrawElements(GL_TRIANGLES, (GLsizei) numberOfQuads*, GL_UNSIGNED_SHORT, (GLvoid*) (start**sizeof(_indices[])) ); #if CC_REBIND_INDICES_BUFFER
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, );
#endif // glBindVertexArray(0);
}
else
{
//
// Using VBO without VAO
// #define kQuadSize sizeof(_quads[0].bl)
glBindBuffer(GL_ARRAY_BUFFER, _buffersVBO[]); // XXX: update is done in draw... perhaps it should be done in a timer
if (_dirty)
{
glBufferSubData(GL_ARRAY_BUFFER, sizeof(_quads[])*start, sizeof(_quads[]) * numberOfQuads , &_quads[start] );
_dirty = false;
} GL::enableVertexAttribs(GL::VERTEX_ATTRIB_FLAG_POS_COLOR_TEX); // vertices
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, , GL_FLOAT, GL_FALSE, kQuadSize, (GLvoid*) offsetof(V3F_C4B_T2F, vertices)); // colors
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_COLOR, , GL_UNSIGNED_BYTE, GL_TRUE, kQuadSize, (GLvoid*) offsetof(V3F_C4B_T2F, colors)); // tex coords
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_TEX_COORD, , GL_FLOAT, GL_FALSE, kQuadSize, (GLvoid*) offsetof(V3F_C4B_T2F, texCoords)); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _buffersVBO[]); glDrawElements(GL_TRIANGLES, (GLsizei)numberOfQuads*, GL_UNSIGNED_SHORT, (GLvoid*) (start**sizeof(_indices[]))); glBindBuffer(GL_ARRAY_BUFFER, );
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, );
} CC_INCREMENT_GL_DRAWN_BATCHES_AND_VERTICES(,numberOfQuads*); CHECK_GL_ERROR_DEBUG();
}
以上主要步骤完成了SpriteBatchNode中sprite的绘制