Cocos2d-x 3.2学习笔记（三）学习绘图API

　　关于cocos2d-x 3.2 版本的绘图方法有两种

　　1、使用DrawNode类绘制自定义图形。

　　2、继承Layer类重写draw()方法。

　　以上两种方法都可以绘制自定义图形，根据自己的需要选择合适的方法。

一、使用DrawNode类绘制自定义图形

　　使用DrawNode 类绘制图形是最简单的方法，create一个DrawNode类，然后添加进场景。然后就可以愉快的绘图了。

　　

    auto s = Director::getInstance()->getWinSize();
　　 //创建
    auto draw = DrawNode::create();
    this->addChild(draw, 10);

    // 画圆
    for( int i=0; i < 10; i++)
    {
        draw->drawDot(Vec2(s.width/2, s.height/2), 10*(10-i), Color4F(CCRANDOM_0_1(), CCRANDOM_0_1(), CCRANDOM_0_1(), 1));
    }

    // 画多边形
    Vec2 points[] = { Vec2(s.height/4,0), Vec2(s.width,s.height/5), Vec2(s.width/3*2,s.height) };
    draw->drawPolygon(points, sizeof(points)/sizeof(points[0]), Color4F(1,0,0,0.5), 4, Color4F(0,0,1,1));

    // 画线
    draw->drawSegment(Vec2(20,s.height), Vec2(20,s.height/2), 10, Color4F(0, 1, 0, 1));

    draw->drawSegment(Vec2(10,s.height/2), Vec2(s.width/2, s.height/2), 40, Color4F(1, 0, 1, 0.5));

    // 画三角形
    draw->drawTriangle(Vec2(10, 10), Vec2(70, 30), Vec2(100, 140), Color4F(CCRANDOM_0_1(), CCRANDOM_0_1(), CCRANDOM_0_1(), 0.5));

    // 画贝赛尔曲线
    draw->drawQuadraticBezier(Vec2(s.width - 150, s.height - 150), Vec2(s.width - 70, s.height - 10), Vec2(s.width - 10, s.height - 10), 10, Color4F(CCRANDOM_0_1(), CCRANDOM_0_1(), CCRANDOM_0_1(), 0.5));

    draw->drawCubicBezier(Vec2(s.width - 250, 40), Vec2(s.width - 70, 100), Vec2(s.width - 30, 250), Vec2(s.width - 10, s.height - 50), 10, Color4F(CCRANDOM_0_1(), CCRANDOM_0_1(), CCRANDOM_0_1(), 0.5));

　　根据需要可以用这些api创造出自己需要的图像。

二、继承Layer类重写draw()方法

　　这种方式可以自定义一个绘图类，用于创作自己需要的图形。

　　

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__
#include "cocos2d.h"
USING_NS_CC;

class HelloWorld : public cocos2d::Layer
{
public:
        virtual void draw(Renderer *renderer, const Mat4 &transform, bool transformUpdated) override;
protected:  
    void onDraw(const kmMat4 &transform, bool transformUpdated);  
    CustomCommand _customCommand;  
};
#endif

#include "HelloWorldScene.h"
#include "VisibleRect.h"

void HelloWorld::draw(cocos2d::Renderer *renderer, const kmMat4 &transform, bool transformUpdated)  
{  
    _customCommand.init(1);  
    _customCommand.func = CC_CALLBACK_0(HelloWorld::onDraw, this,transform,transformUpdated);  
    renderer->addCommand(&_customCommand);  
}

void HelloWorld::onDraw(const kmMat4 &transform, bool transformUpdated)  
{  
    kmGLPushMatrix();  
    kmGLLoadMatrix(&transform);  


    /*直线*/  
    CHECK_GL_ERROR_DEBUG();  
    DrawPrimitives::drawLine(VisibleRect::leftBottom(), VisibleRect::rightTop());  


    CHECK_GL_ERROR_DEBUG();  

    glLineWidth( 5.0f );  
    DrawPrimitives::setDrawColor4B(255,0,0,255);  
    DrawPrimitives::drawLine( Point(0, 0), Point(100, 100) );  

    // draw big point in the center  
    DrawPrimitives::setPointSize(64);  
    DrawPrimitives::setDrawColor4B(100, 0, 255, 128);  
    DrawPrimitives::drawPoint(VisibleRect::center());  
    CHECK_GL_ERROR_DEBUG();  


    // draw 4 small points  
    Point points[] = { Point(60,60), Point(70,70), Point(160,70), Point(170,60) };  
    DrawPrimitives::setPointSize(10);  
    DrawPrimitives::setDrawColor4B(0,10,255,255);  
    DrawPrimitives::drawPoints( points, 4);  

    CHECK_GL_ERROR_DEBUG();  


    // draw a green circle with 10 segments  
    glLineWidth(16);  
    DrawPrimitives::setDrawColor4B(0, 255, 0, 255);  
    DrawPrimitives::drawCircle( VisibleRect::center(), 100, 0, 10, false);  

    CHECK_GL_ERROR_DEBUG();  

    // draw a green circle with 50 segments with line to center  
    glLineWidth(2);  
    DrawPrimitives::setDrawColor4B(0, 255, 255, 255);  
    DrawPrimitives::drawCircle( VisibleRect::center(), 150, CC_DEGREES_TO_RADIANS(90), 50, false);  

    CHECK_GL_ERROR_DEBUG();  

    // draw a pink solid circle with 50 segments  
    glLineWidth(2);  
    DrawPrimitives::setDrawColor4B(255, 0, 255, 255);  
    DrawPrimitives::drawSolidCircle( VisibleRect::center() + Point(140,0), 40, CC_DEGREES_TO_RADIANS(90), 50, 1.0f, 1.0f);  

    CHECK_GL_ERROR_DEBUG();  

    // open yellow poly  
    DrawPrimitives::setDrawColor4B(255, 255, 0, 255);  
    glLineWidth(5);  
    Point vertices[] = { Point(10,10), Point(50,50), Point(100,50), Point(150,100), Point(200,150) };  
    DrawPrimitives::drawPoly( vertices, 5, false);  

    CHECK_GL_ERROR_DEBUG();  

    // filled poly  
    glLineWidth(1);  
    Point filledVertices[] = { Point(0,120), Point(50,120), Point(50,170), Point(25,200), Point(0,170) };  
    DrawPrimitives::drawSolidPoly(filledVertices, 5, Color4F(0.5f, 0.5f, 1, 1 ) );  


    // closed purble poly  
    DrawPrimitives::setDrawColor4B(255, 0, 255, 255);  
    glLineWidth(2);  
    Point vertices2[] = { Point(30,130), Point(30,230), Point(50,200) };  
    DrawPrimitives::drawPoly( vertices2, 3, true);  

    CHECK_GL_ERROR_DEBUG();  

    // draw quad bezier path  
    DrawPrimitives::drawQuadBezier(VisibleRect::leftTop(), VisibleRect::center(), VisibleRect::rightTop(), 50);  

    CHECK_GL_ERROR_DEBUG();  


    // draw cubic bezier path  
    DrawPrimitives::drawCubicBezier(VisibleRect::center(), Point(VisibleRect::center().x+30,VisibleRect::center().y+150), Point(VisibleRect::center().x+60,VisibleRect::center().y-300),Point(VisibleRect::center().x+90,VisibleRect::center().y+150),100);  


    CHECK_GL_ERROR_DEBUG();  


    //draw a solid polygon  
    Point vertices3[] = {Point(60,160), Point(70,190), Point(100,190), Point(90,160)};  
    DrawPrimitives::drawSolidPoly( vertices3, 4, Color4F(1,1,0,1) );  

    CHECK_GL_ERROR_DEBUG();  

    //end draw  
    kmGLPopMatrix();  
}  

　　其中涉及到辅助类VisibleRect类得到获取视口。

#ifndef __VISIBLERECT_H__
#define __VISIBLERECT_H__

#include "cocos2d.h"

class VisibleRect
{
public:
    static cocos2d::Rect getVisibleRect();

    static cocos2d::Vec2 left();
    static cocos2d::Vec2 right();
    static cocos2d::Vec2 top();
    static cocos2d::Vec2 bottom();
    static cocos2d::Vec2 center();
    static cocos2d::Vec2 leftTop();
    static cocos2d::Vec2 rightTop();
    static cocos2d::Vec2 leftBottom();
    static cocos2d::Vec2 rightBottom();
private:
    static void lazyInit();
    static cocos2d::Rect s_visibleRect;
};

#endif /* __VISIBLERECT_H__ */

#include "VisibleRect.h"

USING_NS_CC;

Rect VisibleRect::s_visibleRect;

void VisibleRect::lazyInit()
{
    // no lazy init
    // Useful if we change the resolution in runtime
    s_visibleRect = Director::getInstance()->getOpenGLView()->getVisibleRect();
}

Rect VisibleRect::getVisibleRect()
{
    lazyInit();
    return s_visibleRect;
}

Vec2 VisibleRect::left()
{
    lazyInit();
    return Vec2(s_visibleRect.origin.x, s_visibleRect.origin.y+s_visibleRect.size.height/2);
}

Vec2 VisibleRect::right()
{
    lazyInit();
    return Vec2(s_visibleRect.origin.x+s_visibleRect.size.width, s_visibleRect.origin.y+s_visibleRect.size.height/2);
}

Vec2 VisibleRect::top()
{
    lazyInit();
    return Vec2(s_visibleRect.origin.x+s_visibleRect.size.width/2, s_visibleRect.origin.y+s_visibleRect.size.height);
}

Vec2 VisibleRect::bottom()
{
    lazyInit();
    return Vec2(s_visibleRect.origin.x+s_visibleRect.size.width/2, s_visibleRect.origin.y);
}

Vec2 VisibleRect::center()
{
    lazyInit();
    return Vec2(s_visibleRect.origin.x+s_visibleRect.size.width/2, s_visibleRect.origin.y+s_visibleRect.size.height/2);
}

Vec2 VisibleRect::leftTop()
{
    lazyInit();
    return Vec2(s_visibleRect.origin.x, s_visibleRect.origin.y+s_visibleRect.size.height);
}

Vec2 VisibleRect::rightTop()
{
    lazyInit();
    return Vec2(s_visibleRect.origin.x+s_visibleRect.size.width, s_visibleRect.origin.y+s_visibleRect.size.height);
}

Vec2 VisibleRect::leftBottom()
{
    lazyInit();
    return s_visibleRect.origin;
}

Vec2 VisibleRect::rightBottom()
{
    lazyInit();
    return Vec2(s_visibleRect.origin.x+s_visibleRect.size.width, s_visibleRect.origin.y);
}