Cocos2dx 绘制流程总结

Cocos2dx 绘制流程总结

1.   创建CCDirector.  

代码：CCDirector *pDirector = CCDirector::sharedDirector();

2.   设置openglView.

代码：

pDirector->setOpenGLView(CCEGLView::sharedOpenGLView());

重要内容：setOpenglGLView->setGLDefaultValues，其中设置了视口大小，颜色混合，深度检测，清屏颜色，摄像机透视类型等。

3．主循环mainloop->drawScene

   visit方法访问了所有子节点的draw方法。

4．单个节点绘制

   以CCSprite为例：

   void CCSprite::draw(void)

{

    CC_PROFILER_START_CATEGORY(kCCProfilerCategorySprite,"CCSprite - draw");

 

    CCAssert(!m_pobBatchNode,"If CCSprite is being rendered byCCSpriteBatchNode, CCSprite#draw SHOULD NOT be called");

 

    CC_NODE_DRAW_SETUP();

 

    ccGLBlendFunc( m_sBlendFunc.src, m_sBlendFunc.dst );

 

    if (m_pobTexture !=NULL)

    {

        ccGLBindTexture2D( m_pobTexture->getName() );

    }

    else

    {

        ccGLBindTexture2D(0);

    }

   

    //

    // Attributes

    //

 

    ccGLEnableVertexAttribs( kCCVertexAttribFlag_PosColorTex );

 

#definekQuadSize sizeof(m_sQuad.bl)

    long offset= (long)&m_sQuad;

 

    // vertex

    int diff = offsetof( ccV3F_C4B_T2F, vertices);

    glVertexAttribPointer(kCCVertexAttrib_Position,3,GL_FLOAT,GL_FALSE,kQuadSize, (void*)(offset + diff));

 

    // texCoods

    diff = offsetof( ccV3F_C4B_T2F, texCoords);

    glVertexAttribPointer(kCCVertexAttrib_TexCoords,2,GL_FLOAT,GL_FALSE,kQuadSize, (void*)(offset+ diff));

 

    // color

    diff = offsetof( ccV3F_C4B_T2F, colors);

    glVertexAttribPointer(kCCVertexAttrib_Color,4,GL_UNSIGNED_BYTE,GL_TRUE,kQuadSize, (void*)(offset+ diff));

 

 

    glDrawArrays(GL_TRIANGLE_STRIP,0,4);

 

    CHECK_GL_ERROR_DEBUG();

 

 

#ifCC_SPRITE_DEBUG_DRAW == 1

    // draw bounding box

    CCPoint vertices[4]={

       ccp(m_sQuad.tl.vertices.x,m_sQuad.tl.vertices.y),

       ccp(m_sQuad.bl.vertices.x,m_sQuad.bl.vertices.y),

       ccp(m_sQuad.br.vertices.x,m_sQuad.br.vertices.y),

       ccp(m_sQuad.tr.vertices.x,m_sQuad.tr.vertices.y),

    };

    ccDrawPoly(vertices, 4, true);

#elifCC_SPRITE_DEBUG_DRAW == 2

    // draw texture box

    CCSize s = this->getTextureRect().size;

    CCPoint offsetPix = this->getOffsetPosition();

    CCPoint vertices[4] = {

        ccp(offsetPix.x,offsetPix.y),ccp(offsetPix.x+s.width,offsetPix.y),

       ccp(offsetPix.x+s.width,offsetPix.y+s.height),ccp(offsetPix.x,offsetPix.y+s.height)

    };

    ccDrawPoly(vertices, 4, true);

#endif// CC_SPRITE_DEBUG_DRAW

 

    CC_INCREMENT_GL_DRAWS(1);

 

    CC_PROFILER_STOP_CATEGORY(kCCProfilerCategorySprite,"CCSprite - draw");

}