cocos2dx学习笔记：CCDrawNode

最近看了下CCDrawNode的实现，这里笔记下实现方式。
CONTENTS
参考

CCDrawNode需要很多基础知识，之前记录过，这里贴下网址：
VBO的讲解：【转】OpenGL ES使用VBO:顶点缓存
opengl混合：【转】OpenGL ES 混合的理解
cocos2dx封装的一些opengl函数：cocos2dx学习笔记：CCGLProgram
cocos2dx自带的shaders：cocos2dx学习笔记：shaders
代码笔记

记的比较乱。
NS_CC_BEGIN

// ccVertex2F == CGPoint in 32-bits, but not in 64-bits (OS X)
// that's why the "v2f" functions are needed
static ccVertex2F v2fzero = {0.0f,0.0f};
。。。。。
//工具函数
。。。。。

// implementation of CCDrawNode

CCDrawNode::CCDrawNode()
: m_uVao(0)
, m_uVbo(0)
, m_uBufferCapacity(0)
, m_nBufferCount(0)
, m_pBuffer(NULL)
, m_bDirty(false)
{
    m_sBlendFunc.src = CC_BLEND_SRC;
    m_sBlendFunc.dst = CC_BLEND_DST;
}

CCDrawNode::~CCDrawNode()
{
    free(m_pBuffer);
    m_pBuffer = NULL;
    //==>> 删除顶点缓存buffer（vbo）
    glDeleteBuffers(1, &m_uVbo);
    m_uVbo = 0;
    
#if CC_TEXTURE_ATLAS_USE_VAO      
    glDeleteVertexArrays(1, &m_uVao);
    ccGLBindVAO(0);
    m_uVao = 0;
#endif

#if CC_ENABLE_CACHE_TEXTURE_DATA
    CCNotificationCenter::sharedNotificationCenter()->removeObserver(this, EVENT_COME_TO_FOREGROUND);
#endif    
}

CCDrawNode* CCDrawNode::create()
{
    CCDrawNode* pRet = new CCDrawNode();
    if (pRet && pRet->init())
    {
        pRet->autorelease();
    }
    else
    {
        CC_SAFE_DELETE(pRet);
    }
    
    return pRet;
}
//==>> 扩容顶点缓存节点
void CCDrawNode::ensureCapacity(unsigned int count)
{
    if(m_nBufferCount + count > m_uBufferCapacity)
    {
		m_uBufferCapacity += MAX(m_uBufferCapacity, count);
		m_pBuffer = (ccV2F_C4B_T2F*)realloc(m_pBuffer, m_uBufferCapacity*sizeof(ccV2F_C4B_T2F));
	}
}

bool CCDrawNode::init()
{
		/*
	ccMacros.h
#define CC_BLEND_SRC GL_ONE
#define CC_BLEND_DST GL_ONE_MINUS_SRC_ALPHA
	*/
	//通过宏的定义我们知道默认的混合方式是 要绘制上去颜色的100%绘制
	//其余的地方100%绘制底色。
    m_sBlendFunc.src = CC_BLEND_SRC;
    m_sBlendFunc.dst = CC_BLEND_DST;

		//==>>使用PositionLengthTexureColor这个shader
    setShaderProgram(CCShaderCache::sharedShaderCache()->programForKey(kCCShader_PositionLengthTexureColor));
    
    //==>>先扩容到512个顶点缓存节点
    ensureCapacity(512);
    
#if CC_TEXTURE_ATLAS_USE_VAO    
    glGenVertexArrays(1, &m_uVao);
    ccGLBindVAO(m_uVao);
#endif
    
    //==>>申请一块vbo，并且将m_pBuffer刷入vbo中
    glGenBuffers(1, &m_uVbo);
    glBindBuffer(GL_ARRAY_BUFFER, m_uVbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(ccV2F_C4B_T2F)* m_uBufferCapacity, m_pBuffer, GL_STREAM_DRAW);
    
/*
ccTypes.h:
typedef struct _ccV2F_C4B_T2F
{
    //! vertices (2F)
    ccVertex2F        vertices;
    //! colors (4B)
    ccColor4B        colors;
    //! tex coords (2F)
    ccTex2F            texCoords;
} ccV2F_C4B_T2F;
*/    
    //==>>允许设置位置坐标
    glEnableVertexAttribArray(kCCVertexAttrib_Position);
		//==>>由于是vbo状态，那么glVertexAttribPointer的最后一个参数表示该种类型顶点数据（vertices）在顶点缓存（ccV2F_C4B_T2F）中的起始偏移量。
    glVertexAttribPointer(kCCVertexAttrib_Position, 2, GL_FLOAT, GL_FALSE, sizeof(ccV2F_C4B_T2F), (GLvoid *)offsetof(ccV2F_C4B_T2F, vertices));
    
    glEnableVertexAttribArray(kCCVertexAttrib_Color);
    glVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ccV2F_C4B_T2F), (GLvoid *)offsetof(ccV2F_C4B_T2F, colors));
    
    glEnableVertexAttribArray(kCCVertexAttrib_TexCoords);
    glVertexAttribPointer(kCCVertexAttrib_TexCoords, 2, GL_FLOAT, GL_FALSE, sizeof(ccV2F_C4B_T2F), (GLvoid *)offsetof(ccV2F_C4B_T2F, texCoords));
    
    //==>>设置好数据之后，将vbo解绑，防止对opengl上下文产生影响。
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    
#if CC_TEXTURE_ATLAS_USE_VAO 
    ccGLBindVAO(0);
#endif
    
    CHECK_GL_ERROR_DEBUG();
    
    //==>> 设置数据需要刷新
    m_bDirty = true;

#if CC_ENABLE_CACHE_TEXTURE_DATA
    // Need to listen the event only when not use batchnode, because it will use VBO
    CCNotificationCenter::sharedNotificationCenter()->addObserver(this,
            callfuncO_selector(CCDrawNode::listenBackToForeground),
            EVENT_COME_TO_FOREGROUND,
            NULL);
#endif

    return true;
}

//==>>实际渲染实现类
void CCDrawNode::render()
{
//==>>如果数据需要刷新，那么首先重新绑定vbo，然后将m_pBuffer的数据刷入vbo中，这样做的原因主要是
//==>>避免每次都要刷新vbo，提高效率。	
    if (m_bDirty)
    {
        glBindBuffer(GL_ARRAY_BUFFER, m_uVbo);
        glBufferData(GL_ARRAY_BUFFER, sizeof(ccV2F_C4B_T2F)*m_uBufferCapacity, m_pBuffer, GL_STREAM_DRAW);
        m_bDirty = false;
    }
#if CC_TEXTURE_ATLAS_USE_VAO     
    ccGLBindVAO(m_uVao);
#else

//==>> 首先允许位置，颜色，纹理刷新
/*
ccGLStateCache.h
enum {
    kCCVertexAttribFlag_None        = 0,

    kCCVertexAttribFlag_Position    = 1 << 0,
    kCCVertexAttribFlag_Color       = 1 << 1,
    kCCVertexAttribFlag_TexCoords   = 1 << 2,

    kCCVertexAttribFlag_PosColorTex = ( kCCVertexAttribFlag_Position | kCCVertexAttribFlag_Color | kCCVertexAttribFlag_TexCoords ),
};
*/
//==>> 重新绑定vbo，并且使用vbo中的数据
    ccGLEnableVertexAttribs(kCCVertexAttribFlag_PosColorTex);
    glBindBuffer(GL_ARRAY_BUFFER, m_uVbo);
    // vertex
    glVertexAttribPointer(kCCVertexAttrib_Position, 2, GL_FLOAT, GL_FALSE, sizeof(ccV2F_C4B_T2F), (GLvoid *)offsetof(ccV2F_C4B_T2F, vertices));
    
    // color
    glVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ccV2F_C4B_T2F), (GLvoid *)offsetof(ccV2F_C4B_T2F, colors));
    
    // texcood
    glVertexAttribPointer(kCCVertexAttrib_TexCoords, 2, GL_FLOAT, GL_FALSE, sizeof(ccV2F_C4B_T2F), (GLvoid *)offsetof(ccV2F_C4B_T2F, texCoords));
#endif

//==>> 绘图
    glDrawArrays(GL_TRIANGLES, 0, m_nBufferCount);
//==>> 解绑vbo，防止对opengl上下文产生影响。
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    
    CC_INCREMENT_GL_DRAWS(1);
    CHECK_GL_ERROR_DEBUG();
}

//==>> draw函数每帧都会被调用，因此需要在render里面绘制需要的东西，而且搞定后不能对opengl上下文造成影响。
void CCDrawNode::draw()
{
    CC_NODE_DRAW_SETUP();
//==>> 设置混合模式
    ccGLBlendFunc(m_sBlendFunc.src, m_sBlendFunc.dst);
    
    render();
}

//==>> 画点的实际方式是将点的信息放入m_pBuffer中，然后设置m_bDirty，这样就可以在render中画出来了。
void CCDrawNode::drawDot(const CCPoint &pos, float radius, const ccColor4F &color)
{
    unsigned int vertex_count = 2*3;
    ensureCapacity(vertex_count);
	
	ccV2F_C4B_T2F a = {{pos.x - radius, pos.y - radius}, ccc4BFromccc4F(color), {-1.0, -1.0} };
	ccV2F_C4B_T2F b = {{pos.x - radius, pos.y + radius}, ccc4BFromccc4F(color), {-1.0,  1.0} };
	ccV2F_C4B_T2F c = {{pos.x + radius, pos.y + radius}, ccc4BFromccc4F(color), { 1.0,  1.0} };
	ccV2F_C4B_T2F d = {{pos.x + radius, pos.y - radius}, ccc4BFromccc4F(color), { 1.0, -1.0} };
	
	//==>> 计算出需要更新的m_pBuffer
	ccV2F_C4B_T2F_Triangle *triangles = (ccV2F_C4B_T2F_Triangle *)(m_pBuffer + m_nBufferCount);
    ccV2F_C4B_T2F_Triangle triangle0 = {a, b, c};
    ccV2F_C4B_T2F_Triangle triangle1 = {a, c, d};
	triangles[0] = triangle0;
	triangles[1] = triangle1;
	
	m_nBufferCount += vertex_count;
	
	m_bDirty = true;
}

//==>> 和drawDot类似，计算数据>更新m_pBuffer中特定内存>设置m_bDirty
void CCDrawNode::drawSegment(const CCPoint &from, const CCPoint &to, float radius, const ccColor4F &color)
{
。。。。。
。。。。。
}
//==>> 和drawDot类似，计算数据>更新m_pBuffer中特定内存>设置m_bDirty
void CCDrawNode::drawPolygon(CCPoint *verts, unsigned int count, const ccColor4F &fillColor, float borderWidth, const ccColor4F &borderColor)
{
。。。。。
。。。。。
}
//==>> 设置m_pBuffer中有效数据的个数为0，然后设置m_bDirty，就会将vbo中的数据清空。
void CCDrawNode::clear()
{
    m_nBufferCount = 0;
    m_bDirty = true;
}

ccBlendFunc CCDrawNode::getBlendFunc() const
{
    return m_sBlendFunc;
}

void CCDrawNode::setBlendFunc(const ccBlendFunc &blendFunc)
{
    m_sBlendFunc = blendFunc;
}

/** listen the event that coming to foreground on Android
 */
void CCDrawNode::listenBackToForeground(CCObject *obj)
{
    init();
}

NS_CC_END
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参考

代码笔记

cstriker1407

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Contents

cocos2dx学习笔记：CCDrawNode

参考

代码笔记

cstriker1407

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