[cocos2d-x 3.2]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。
1 auto s = Director::getInstance()->getWinSize(); 2 //创建 3 auto draw = DrawNode::create(); 4 this->addChild(draw, 10); 5 6 // 画圆 7 for( int i=0; i < 10; i++) 8 { 9 draw->drawDot(Vec2(s.width/2, s.height/2), 10*(10-i), Color4F(CCRANDOM_0_1(), CCRANDOM_0_1(), CCRANDOM_0_1(), 1));10 }11 12 // 画多边形13 Vec2 points[] = { Vec2(s.height/4,0), Vec2(s.width,s.height/5), Vec2(s.width/3*2,s.height) };14 draw->drawPolygon(points, sizeof(points)/sizeof(points[0]), Color4F(1,0,0,0.5), 4, Color4F(0,0,1,1));15 16 // 画线17 draw->drawSegment(Vec2(20,s.height), Vec2(20,s.height/2), 10, Color4F(0, 1, 0, 1));18 19 draw->drawSegment(Vec2(10,s.height/2), Vec2(s.width/2, s.height/2), 40, Color4F(1, 0, 1, 0.5));20 21 // 画三角形22 draw->drawTriangle(Vec2(10, 10), Vec2(70, 30), Vec2(100, 140), Color4F(CCRANDOM_0_1(), CCRANDOM_0_1(), CCRANDOM_0_1(), 0.5));23 24 // 画贝赛尔曲线25 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));26 27 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();
}