[Cocos2d-x For WP8]DrawPrimitives画图

    在Silverlight框架的WP8应用程序里面，我们画几何图形的时候会通过Line等等的类在用C#代码或者在XAML上画图，那么在Cocos2d-x For WP8里面我们一样也可以实现这样的功能。那么在Cocos2d-x中画图的逻辑要放在自己写的draw函数里面，这样图形引擎才会把你的图形给画出来。

比如说：

将画一条直线放到下面这函数是画不出来的

bool HelloWorld::init()

{

ccDrawLine( ccp(0, 0), ccp(s.width, s.height) ); CHECK_GL_ERROR_DEBUG();

}

而放到draw函数就能画出来，也不需要调用

void HelloWorld::draw()

{

ccDrawLine( ccp(0, 0), ccp(s.width, s.height) ); CHECK_GL_ERROR_DEBUG();

}

示例代码：

void HelloWorld::draw()
{
    CCLayer::draw();

    CCSize s = CCDirector::sharedDirector()->getWinSize();
    
    // 画两条对角的直线
    // 默认的数值:
    // Line Width: 1
    // color: 255,255,255,255 (white, non-transparent)
    // Anti-Aliased
    //glEnable(GL_LINE_SMOOTH);
    //ccDrawLine( CCPointMake(0, 0), CCPointMake(s.width, s.height) );
    
    // line: color, width, aliased
    //glDisable(GL_LINE_SMOOTH);
    //glLineWidth( 5.0f );
    /*glColor4ub(255,0,0,255);*/
    CCDrawingPrimitive::D3DColor4f(1.0, 0.0, 0.0, 1.0);
    ccDrawLine( CCPointMake(0, s.height), CCPointMake(s.width, 0) );
    ccDrawLine( CCPointMake(0, 0), CCPointMake(s.width,s.height ) );

    // TIP:
    //如果是使用同一种颜色则不需要重新去调用CCDrawingPrimitive::D3DColor4f方法去设置颜色 I
    //
    // Remember: OpenGL is a state-machine.
    
    // draw big point in the center
    //glPointSize(64);
    /*glColor4ub(0,0,255,128);*/
    CCDrawingPrimitive::D3DColor4f(0.0, 0.0, 1.0, 0.5);
    ccDrawPoint( CCPointMake(65, 65) );
    /*ccDrawPoint( CCPointMake(s.width / 2, s.height / 2) );*/
    
    // draw 4 small points
    CCPoint points[] = { CCPointMake(60,60), CCPointMake(70,70), CCPointMake(60,70), CCPointMake(70,60) };
    //glPointSize(4);
    /*glColor4ub(0,255,255,255);*/
    CCDrawingPrimitive::D3DColor4f(0.0, 1.0, 1.0, 1.0);
    ccDrawPoints( points, 4);
    
    // draw a green circle with 10 segments
    //glLineWidth(16);
    /*glColor4ub(0, 255, 0, 255);*/
    CCDrawingPrimitive::D3DColor4f(0.0, 1.0, 0.0, 1.0);
    ccDrawCircle( CCPointMake(s.width/2,  s.height/2), 100, 0, 10, false);

    // draw a green circle with 50 segments with line to center
    //glLineWidth(2);
    /*glColor4ub(0, 255, 255, 255);*/
    CCDrawingPrimitive::D3DColor4f(0.0, 1.0, 1.0, 1.0);
    ccDrawCircle( CCPointMake(s.width/2, s.height/2), 50, CC_DEGREES_TO_RADIANS(90), 50, true);    
    
    // open yellow poly
    /*glColor4ub(255, 255, 0, 255);*/
    CCDrawingPrimitive::D3DColor4f(1.0, 1.0, 0.0, 1.0);
    //glLineWidth(10);
    CCPoint vertices[] = { CCPointMake(0,0), CCPointMake(50,50), CCPointMake(100,50), CCPointMake(100,100), CCPointMake(50,100) };
    ccDrawPoly( vertices, 5, false);
    
    // closed purble poly
    /*glColor4ub(255, 0, 255, 255);*/
    CCDrawingPrimitive::D3DColor4f(1.0, 0.0, 1.0, 1.0);
    //glLineWidth(2);
    CCPoint vertices2[] = { CCPointMake(30,130), CCPointMake(30,230), CCPointMake(50,200) };
    ccDrawPoly( vertices2, 3, true);
    
    // draw quad bezier path
    ccDrawQuadBezier(CCPointMake(0,s.height), CCPointMake(s.width/2,s.height/2), CCPointMake(s.width,s.height), 50);

    // draw cubic bezier path
    ccDrawCubicBezier(CCPointMake(s.width/2, s.height/2), CCPointMake(s.width/2+30,s.height/2+50), CCPointMake(s.width/2+60,s.height/2-50),CCPointMake(s.width, s.height/2),100);

    
    // restore original values
    //glLineWidth(1);
    /*glColor4ub(255,255,255,255);*/
    CCDrawingPrimitive::D3DColor4f(1.0, 1.0, 1.0, 1.0);
    //glPointSize(1); 
}

运行的效果：