我正在编写自己的绘制线函数以提高从矢量文件中绘制大量线条时的速度(只是一个.txt,其中包含一堆绘制塞维利亚地图的坐标)。我正在使用方法 pixel[int] 来构建这样的函数,但是由于某种原因,当我输入这样的坐标时,我无法解释程序运行得非常快:drawline(y1,x1,y2,x2) 但是当它的时候很慢它应该是怎样的: drawline(x1,y1,x2,y2) 对此有合理的解释吗?
.txt 代码的结构很简单,如下所示(完整的 .txt 文件可以从文件夹下载):
1188156570;1188156570;37.417595;-5.9971519
1188156400;1188156400;37.4175115;-5.9970483
1188156720;1188156720;37.4174588;-5.9969338
1188156606;1188156606;37.4175833;-5.9966021
1188156462;1188156462;37.4177174;-5.9960534
1188156753;1188156753;37.4177413;-5.9958605
1188156643;1188156643;37.417703;-5.9955831
1132983943;1132983943;37.4176646;-5.995381
next
304791377;304791377;37.3968538;-6.0066269
1188156644;1188156644;37.3967509;-6.0064412
1188156521;1188156521;37.3956275;-6.0073602
next
1188216699;1188216699;37.4221365;-5.9959761
693311201;693311201;37.4253619;-5.9951655
1188216625;1188216625;37.4239123;-5.9924734
1188216567;1188216567;37.4233085;-5.9916937
1186512382;1186512382;37.4223597;-5.9910465
1188216642;1188216642;37.4216335;-5.9927836
1188216699;1188216699;37.4221365;-5.9959761
next
下面是处理 1.5.1 草图的代码,我尽可能地缩短了它,并尽可能地使其整洁。谢谢您的帮助!
String[] polylines;
String[] streetArray=new String[0];
String[] empty=new String[0];
ArrayList vlist=new ArrayList();
float panX; float panY;
void setup() {
size(600, 600);
polylines=loadStrings("data/MapSeville.txt");
panX=0; panY=0;
prepare();
}
void draw() {
background(255);
PVector pan = pan();
panX=panX+pan.x;
panY=panY+pan.y;
loadPixels();
for(int i=0;i<vlist.size();i++){
vertexgroup vg= (vertexgroup) vlist.get(i);
for(int j=1;j<vg.listcoord.size();j++){
Vertice v2=(Vertice) vg.listcoord.get((j-1));
Vertice v1=(Vertice) vg.listcoord.get(j);
float x1=v1.coord.x+panX;
float y1=v1.coord.y+panY;
float x2=v2.coord.x+panX;
float y2=v2.coord.y+panY;
drawline(x1, y1, x2, y2);//slow :( comment out this line and enable the next to see how smooth it can go
//drawline(y1, x1, y2, x2);//fast!
}
}
updatePixels();
}
////////////////////////////// functions ////////////////////////////////////////////////
PVector pan(){
PVector p;
if (mousePressed){
p = new PVector(mouseX-pmouseX, mouseY-pmouseY);
}else{
p=new PVector(0,0);
}
return p;
}
////////////////////
void drawline(float x1, float y1, float x2, float y2){
int X1=int(x1);
int X2=int(x2);
color pink = color(0);
if((X2>X1)){
for (int i=0; i<=int(x2-x1); i++){
if (((i+X1)>=0)&&((i+X1)<=width)){
int g=int(y1+((y2-y1)/(x2-x1))*i)*(width) + i + X1;
if ((g<width*height)&&(g>=0)){
pixels[g]=pink;
}
}
}
}else if((X2<X1)){
for (int i=0; i<=int(x1-x2); i++){
if (((i+X2)>=0)&&((i+X2)<=width)){
int f=int(y2+((y2-y1)/(x2-x1))*i)*(width) + i + X2;
if ((f<width*height)&&(f>=0)){
pixels[f]=pink;
}
}
}
}
}
//////////////////////////////
void prepare(){
for (int i=1;i<polylines.length;i++) {
String[] pts = split(polylines[i], ";");
if (pts.length>3) {
streetArray=append(streetArray, polylines[i]); //adds coords strings to the array streetArray
}
if (pts.length==1) { //this is when the coords of a polyline ends: pts[0]==>"next"
vertexgroup vgroup;
vgroup=new vertexgroup(create_polyArr(streetArray)); // this function is defined right below
vlist.add(vgroup);
streetArray=empty;
}}}
ArrayList create_polyArr(String[] streetpts) {
ArrayList arrpts=new ArrayList();
arrpts.clear();
for (int i=0;i<streetpts.length;i++){ //iterates through coords strings of the polyline contained in streetpts
String[] pts = split(streetpts[i], ";");
float x=float(pts[3]);//get the x coord
float y=float(pts[2]);//get the y coord
x=((x+5.95)*15000+width/2);//scale and center coord x
y=((-y+37.40)*15000+height/2);//scale and center coord y
PVector coord=new PVector(x,y);
Vertice govertex=new Vertice(coord);
arrpts.add(govertex);
}
return(arrpts);
}
////////////////////// end functions //////////////////////////////////
//////////////////////// classes ///////////////////////////////////////
class vertexgroup{
ArrayList listcoord;
vertexgroup(ArrayList _listcoord){
listcoord=_listcoord;
}}
//////////
class Vertice{
PVector coord;
Vertice(PVector _coord){
coord=_coord;
}}
////////////////////// end classes ///////////////////////////////////////