cocos2d-x画扇形

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第一步：

在CCDrawingPrimitives.加入如下方法：

          /**画扇形***/
   void drawSolidfanshaped( const Point& center, float radius, float angle, unsigned int segments, float scaleX, float scaleY);
   void drawSolidfanshaped( const Point& center, float radius, float angle, unsigned int segments);

在CCDrawingPrimitives.cpp进行实现

     void drawSolidfanshaped( const Point& center, float radius, float angle, unsigned int segments)
{
   drawSolidfanshaped(center, radius, angle, segments, 1.0f, 1.0f);
}

void drawSolidfanshaped( const Point& center, float radius, float angle, unsigned int segments, float scaleX, float scaleY)
{
   lazy_init();
   const float coef = (float)angle/segments; //系数：一段有多少度，angle为弧度制，要先通过CC_DEGREES_TO_RADIANS（）转化

   GLfloat *vertices = (GLfloat*)calloc( sizeof(GLfloat)*2*(segments+2), 1); //分配内存空间
   if( ! vertices )
       return;

   vertices[0] = center.x;
   vertices[1] = center.y;

   for(unsigned int i = 0;i <= segments; i++) {
       float rads = i*coef;
       GLfloat j = radius * cosf(rads + angle) * scaleX + center.x;
       GLfloat k = radius * sinf(rads + angle) * scaleY + center.y;

       vertices[(i+1)*2] = j;     //x坐标
       vertices[(i+1)*2+1] = k;   //y坐标
   }
   /*vertices[(segments+1)*2] = center.x;
   vertices[(segments+1)*2+1] = center.y;*/

   s_shader->use();
   s_shader->setUniformsForBuiltins();
   s_shader->setUniformLocationWith4fv(s_colorLocation, (GLfloat*) &s_color.r, 1);

   GL::enableVertexAttribs( GL::VERTEX_ATTRIB_FLAG_POSITION );

#ifdef EMSCRIPTEN
   setGLBufferData(vertices, sizeof(GLfloat)*2*(segments+2));
   glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, 0);
#else
   glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);
#endif // EMSCRIPTEN

   glDrawArrays(GL_TRIANGLE_FAN, 0, (GLsizei) segments+1);

   ::free( vertices );

   CC_INCREMENT_GL_DRAWN_BATCHES_AND_VERTICES(1,segments+1);
}

第二步：

在自己创建的类重写如下方法：我的类是：Clock

在.h文件加入

public:
   void draw(Renderer *renderer, const kmMat4 &transform, bool transformUpdated);

protected:
   void onDraw(const kmMat4 &transform, bool transformUpdated);
   CustomCommand _customCommand;

在.cpp文件加入

void CLock::draw(Renderer *renderer, const kmMat4 &transform, bool transformUpdated)
{
   _customCommand.init(_globalZOrder);
   _customCommand.func = CC_CALLBACK_0(CLock::onDraw, this, transform, transformUpdated);
   renderer->addCommand(&_customCommand);
}

void CLock::onDraw(const kmMat4 &transform, bool transformUpdated)
{
   DrawPrimitives::drawSolidfanshaped(Point(m_winSize.width/2,m_winSize.height/2),130,CC_DEGREES_TO_RADIANS(30),100);

}

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