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, );

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

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

     // 画线
     draw->drawSegment(Vec2(,s.height), Vec2(,s.height/), , Color4F(, , , ));

     draw->drawSegment(Vec2(,s.height/), Vec2(s.width/, s.height/), , Color4F(, , , 0.5));

     // 画三角形
     draw->drawTriangle(Vec2(, ), Vec2(, ), Vec2(, ), Color4F(CCRANDOM_0_1(), CCRANDOM_0_1(), CCRANDOM_0_1(), 0.5));

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

     draw->drawCubicBezier(Vec2(s.width - , ), Vec2(s.width - , ), Vec2(s.width - , ), Vec2(s.width - , s.height - ), , 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();
    _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(,,,);
    DrawPrimitives::drawLine( Point(, ), Point(, ) );  

    // draw big point in the center
    DrawPrimitives::setPointSize();
    DrawPrimitives::setDrawColor4B(, , , );
    DrawPrimitives::drawPoint(VisibleRect::center());
    CHECK_GL_ERROR_DEBUG();  

    // draw 4 small points
    Point points[] = { Point(,), Point(,), Point(,), Point(,) };
    DrawPrimitives::setPointSize();
    DrawPrimitives::setDrawColor4B(,,,);
    DrawPrimitives::drawPoints( points, );  

    CHECK_GL_ERROR_DEBUG();  

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

    CHECK_GL_ERROR_DEBUG();  

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

    CHECK_GL_ERROR_DEBUG();  

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

    CHECK_GL_ERROR_DEBUG();  

    // open yellow poly
    DrawPrimitives::setDrawColor4B(, , , );
    glLineWidth();
    Point vertices[] = { Point(,), Point(,), Point(,), Point(,), Point(,) };
    DrawPrimitives::drawPoly( vertices, , false);  

    CHECK_GL_ERROR_DEBUG();  

    // filled poly
    glLineWidth();
    Point filledVertices[] = { Point(,), Point(,), Point(,), Point(,), Point(,) };
    DrawPrimitives::drawSolidPoly(filledVertices, , Color4F(0.5f, 0.5f, ,  ) );  

    // closed purble poly
    DrawPrimitives::setDrawColor4B(, , , );
    glLineWidth();
    Point vertices2[] = { Point(,), Point(,), Point(,) };
    DrawPrimitives::drawPoly( vertices2, , true);  

    CHECK_GL_ERROR_DEBUG();  

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

    CHECK_GL_ERROR_DEBUG();  

    // draw cubic bezier path
    DrawPrimitives::drawCubicBezier(VisibleRect::center(), Point(VisibleRect::center().x+,VisibleRect::center().y+), Point(VisibleRect::center().x+,VisibleRect::center().y-),Point(VisibleRect::center().x+,VisibleRect::center().y+),);  

    CHECK_GL_ERROR_DEBUG();  

    //draw a solid polygon
    Point vertices3[] = {Point(,), Point(,), Point(,), Point(,)};
    DrawPrimitives::drawSolidPoly( vertices3, , Color4F(,,,) );  

    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__ */

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/);
 }

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

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

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

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

 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);
 }

VisibleRect.cpp