（三）学习绘图API

（三）学习绘图API

http://cn.cocos2d-x.org/tutorial/show?id=1273

RichardMillings2014-08-06 14:47:185909 次阅读

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__ */

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);
}

VisibleRect.cpp

来源网址：http://www.cnblogs.com/Richard-Core/p/3836100.html