laser distance sensor

Programming Questions

alexx600

in Programming Questions • 1 year ago

Hi all.I must make some model of laser distance sensor.Idea is quite simple.There is 2 point and i must have a linear function.That function make a red pixel across the screen and stop when there is some black pixel.Then it returns me a distance.

I wrote function and it was quite simple but there i have problem. I wrote linear function using

y1=ax1+b

y2=ax2+b

When x1=x2 it is no function in math "a" is infiniti and it doesn't work properly so i wrote a small extra code what to do when x1=x2.In fact it work ok when x1=x2.There is one extra problem when "a" is big there is printed really small amount of pixel and distance isn't correct.I Know that it can be abstarct so i quote code below.Thanks for all reply.:)

void setup(){

background(#ffffff);

size(X, Y);

pos1 = new PVector(200,200);

pos2=new PVector(210,210);

}

//-------------------------------------------

PVector pos1,pos2;

int X=400;//SZEROKOSC OKNA

int Y=400;//WYSOKOSC OKNA

int Error=0;//ZMIENNA GLOBALNA ODPOWIADAJACE ZA PRZERWANIE PETLI

float CZUJNIK=0;//Z GLOBALNA ODPOWIADAJACE ZA WIDZENIE

int x=0;//Z GLOBALNA DO RYSOWANIA FUNKCJI

int y=0;//Z GLOBALNA DO RYSOWANIA FUNKCJI

int k=0;//Z ODPOWIADAJACA ZA ILOSC WYSWIETLONYCH KLATEK

//color black=#000000;//KOLOR CZARNY POTRZEBNY DO WYKRYWANIA SCIAN

//-------------------------------------------

void draw(){

background(255);//ZAWSZE RYSOWANE PODLOZE

pos1.x=200;

pos1.y=200;

point(pos1.x,pos1.y);

//point(x2,y2);

pos2.x=mouseX;//X PUNKTU 2 PODOZA ZA CURSOREM

pos2.y=mouseY;//Y PUNKTU 2 PODOZA ZA CURSOREM

//x2=20; //X PUNKTU 2 JEST STALE

//y2=250; //Y PUNKTU 2 JEST STALE

//RAMKA GORNA1

stroke(#F2EE64);

fill(#F2EE64);

rect(0,0,180,40);

fill(#ff0000);

text("x1= " + pos1.x, 65, 15);

text("y1= " + pos1.y, 65, 30);

text("x2= " + pos2.x, 125, 15);

text("y2= " + pos2.y, 125, 30);

//------------------------

//CZARNY RECT

stroke(#000000);

fill(0);

rect(370,80,20,180);

rect(180,0,190,40);

//------------------------

//RAMKA GORNA1

stroke(#F2EE64);

fill(#F2EE64);

//rect(180,0,190,40);

fill(#ff0000);

text("CZUJNIK= " + CZUJNIK, 180,20);

//------------------------

CZUJNIK=(rysuj2(pos1,pos2,X,Y));

k=k+1;

println(k);

//if(k==1) //ZABEZPIECZENIA JEŚLI SPRAWDZAM 1 KLATKE

//stop();

}

//KONIEC

//-------------------------------------------

//FUNKCJE

float zao(float x)

{

x=x*10;

x=round(x);

x=x/10;

return(x);

}

//-------------------------------------------

float rysuj2(PVector pos1,PVector pos2,int X,int Y)

{

//a i b to współczynniki

float a=0;

float b=0;

color black=#000000;//KOLOR CZARNY

color cp;//BADANY KOLOR

float odl=0;

//------------------------

//OBLICZENIA FUNKCJI

a=(pos2.y-pos1.y);

a=a/(pos2.x-pos1.x);

b=pos1.y-a*pos1.x;

//------------------------

stroke(#FF0000);

if(pos1.x==pos2.x)

{

if(pos1.y>pos2.y)

for(y=int(pos1.y);Error!=1;y++)

{

if(y==Y)

{ Error=1;}

if(y==0)

{ Error=1;}

fill(#ff0000);

stroke(#ff0000);

//println(pos2.x+" "+y);

cp=get(int(pos1.x),y);

if(cp==black)

{Error=1;

odl=(pos1.y-y);}

point(pos2.x,y);

}

else

for(y=int(pos1.y);Error!=1;y--)

{

if(y==Y)

{ Error=1;}

if(y==0)

{ Error=1;}

fill(#ff0000);

stroke(#ff0000);

// println(pos2.x+" "+y);

cp=get(int(pos1.x),y);

if(cp==black)

{Error=1;

odl=(pos1.y-y);}

point(pos2.x,y);

}

Error=0;

return(odl);

}

//-------------------------------------------

if(pos1.x>pos2.x)

for(x=int(pos1.x);Error!=1;x++)

{

y=int(a*x+b);

if(x==X)

{ Error=1;}

if(x==0)

{ Error=1;}

if(y==Y)

{ Error=1;}

if(y==0)

{ Error=1;}

//------------------------

cp=get(x,y);

if(cp==black)

{Error=1;

odl=(pos1.x-x)*(pos1.x-x)+(pos1.y-y)*(pos1.y-y);

odl=sqrt(odl);}

point(x,y);

}

else

for(x=int(pos1.x);Error!=1;x--)

{

y=int(a*x+b);

if(x==X)

{ Error=1;}

if(x==0)

{ Error=1;}

if(y==Y)

{ Error=1;}

if(y==0)

{ Error=1;}

//------------------------

cp=get(x,y);

if(cp==black)

{Error=1;

odl=(pos1.x-x)*(pos1.x-x)+(pos1.y-y)*(pos1.y-y);

odl=sqrt(odl);}

point(x,y);

}

Error=0;

x=0;

y=0;

return(odl);

}

//-------------------------------------------

void keyPressed()

{

if(key=='q')

{exit(); }

}

//-------------------------------------------

Replies(3)

Chrisir

Re: laser distance sensor

1 year ago

which line number do you mean?

void setup(){
background(#ffffff);
size(X, Y);
pos1 = new PVector(200,200);
pos2=new PVector(210,210);
}
//-------------------------------------------
//-------------------------------------------
PVector pos1,pos2;
int X=400;//SZEROKOSC OKNA
int Y=400;//WYSOKOSC OKNA
int Error=0;//ZMIENNA GLOBALNA ODPOWIADAJACE ZA PRZERWANIE PETLI
float CZUJNIK=0;//Z GLOBALNA ODPOWIADAJACE ZA WIDZENIE
int x=0;//Z GLOBALNA DO RYSOWANIA FUNKCJI
int y=0;//Z GLOBALNA DO RYSOWANIA FUNKCJI
int k=0;//Z ODPOWIADAJACA ZA ILOSC WYSWIETLONYCH KLATEK
//color black=#000000;//KOLOR CZARNY POTRZEBNY DO WYKRYWANIA SCIAN
//-------------------------------------------
//-------------------------------------------
void draw(){
background(255);//ZAWSZE RYSOWANE PODLOZE
pos1.x=200;
pos1.y=200;
point(pos1.x,pos1.y);
//point(x2,y2);
pos2.x=mouseX;//X PUNKTU 2 PODOZA ZA CURSOREM
pos2.y=mouseY;//Y PUNKTU 2 PODOZA ZA CURSOREM
//x2=20; //X PUNKTU 2 JEST STALE
//y2=250; //Y PUNKTU 2 JEST STALE
//RAMKA GORNA1
stroke(#F2EE64);
fill(#F2EE64);
rect(0,0,180,40);
fill(#ff0000);
text("x1= " + pos1.x, 65, 15);
text("y1= " + pos1.y, 65, 30);
text("x2= " + pos2.x, 125, 15);
text("y2= " + pos2.y, 125, 30);
//------------------------
//CZARNY RECT
stroke(#000000);
fill(0);
rect(370,80,20,180);
rect(180,0,190,40);
//------------------------
//RAMKA GORNA1
stroke(#F2EE64);
fill(#F2EE64);
//rect(180,0,190,40);
fill(#ff0000);
text("CZUJNIK= " + CZUJNIK, 180,20);
//------------------------
CZUJNIK=(rysuj2(pos1,pos2,X,Y));
k=k+1;
println(k);
//if(k==1) //ZABEZPIECZENIA JEŚLI SPRAWDZAM 1 KLATKE
//stop();
}
//KONIEC
//-------------------------------------------
//-------------------------------------------
//FUNKCJE
float zao(float x)
{
x=x*10;
x=round(x);
x=x/10;
return(x);
}
//-------------------------------------------
//-------------------------------------------
float rysuj2(PVector pos1,PVector pos2,int X,int Y)
{
//a i b to współczynniki
float a=0;
float b=0;
color black=#000000;//KOLOR CZARNY
color cp;//BADANY KOLOR
float odl=0;
//------------------------
//OBLICZENIA FUNKCJI
a=(pos2.y-pos1.y);
a=a/(pos2.x-pos1.x);
b=pos1.y-a*pos1.x;
//------------------------
//------------------------
stroke(#FF0000);
if(pos1.x==pos2.x)
{
if(pos1.y>pos2.y)
for(y=int(pos1.y);Error!=1;y++)
{
if(y==Y)
{ Error=1;}
if(y==0)
{ Error=1;}
fill(#ff0000);
stroke(#ff0000);
//println(pos2.x+" "+y);
cp=get(int(pos1.x),y);
if(cp==black)
{Error=1;
odl=(pos1.y-y);}
point(pos2.x,y);
}
else
for(y=int(pos1.y);Error!=1;y--)
{
if(y==Y)
{ Error=1;}
if(y==0)
{ Error=1;}
fill(#ff0000);
stroke(#ff0000);
// println(pos2.x+" "+y);
cp=get(int(pos1.x),y);
if(cp==black)
{Error=1;
odl=(pos1.y-y);}
point(pos2.x,y);
}
Error=0;
return(odl);
}
//-------------------------------------------
//-------------------------------------------
if(pos1.x>pos2.x)
for(x=int(pos1.x);Error!=1;x++)
{
y=int(a*x+b);
if(x==X)
{ Error=1;}
if(x==0)
{ Error=1;}
if(y==Y)
{ Error=1;}
if(y==0)
{ Error=1;}
//------------------------
cp=get(x,y);
if(cp==black)
{Error=1;
odl=(pos1.x-x)*(pos1.x-x)+(pos1.y-y)*(pos1.y-y);
odl=sqrt(odl);}
point(x,y);
}
else
for(x=int(pos1.x);Error!=1;x--)
{
y=int(a*x+b);
if(x==X)
{ Error=1;}
if(x==0)
{ Error=1;}
if(y==Y)
{ Error=1;}
if(y==0)
{ Error=1;}
//------------------------
cp=get(x,y);
if(cp==black)
{Error=1;
odl=(pos1.x-x)*(pos1.x-x)+(pos1.y-y)*(pos1.y-y);
odl=sqrt(odl);}
point(x,y);
}
Error=0;
x=0;
y=0;
return(odl);
}
//-------------------------------------------
//-------------------------------------------
void keyPressed()
{
if(key=='q')
{exit(); }
}
//-------------------------------------------//------------------------------------------

PhiLho

Re: laser distance sensor

1 year ago

Good you made some comments. Too bad I don't read Polish (if that's this language. I am not a specialist of East Europe languages).

Note that good indentation is important too for easy reading of code.
Fortunately, we have Ctrl+T in the PDE to re-format your code.

Some generic notes:
- X and Y aren't very good names for the dimension of the sketch.
- In Processing, it is better to put numerical values in size() (because they are used when exporting the sketch), and to use the width and height constants instead. (I made the same error when I started...)
- The small red text on black background is hard to read, at least for me.
- For variables like Error taking only two values (0 and 1) used only in tests, it is better to use a boolean variable instead of int. Thus you can set it to true or false and you can test it like for (y = int(pos1.y); Error; y--)

When a becomes big (in absolute value), you are starting to have problems. That's because for such values, the step between two points becomes bigger than the sketch's dimensions!
The cure is to increment on y not only on a specific value (when a is infinite) but much earlier. The positive side effect is that the ray is less diluted in these cases.
I also used a trick to reduce code duplication, doing the increment / decrement of the relevant variable depending on a boolean variable computed upfront.
Code can be simplified further, but I kept changes minimal so you can recognize your code...

void setup() {
size(400, 400);
background(#ffffff);
pos1 = new PVector(200, 200);
pos2=new PVector(210, 210);
}
//-------------------------------------------
//-------------------------------------------
PVector pos1, pos2;
int Error=0;//ZMIENNA GLOBALNA ODPOWIADAJACE ZA PRZERWANIE PETLI
float CZUJNIK=0;//Z GLOBALNA ODPOWIADAJACE ZA WIDZENIE
int x=0;//Z GLOBALNA DO RYSOWANIA FUNKCJI
int y=0;//Z GLOBALNA DO RYSOWANIA FUNKCJI
int k=0;//Z ODPOWIADAJACA ZA ILOSC WYSWIETLONYCH KLATEK
//color black=#000000;//KOLOR CZARNY POTRZEBNY DO WYKRYWANIA SCIAN
//-------------------------------------------
//-------------------------------------------
void draw() {
background(255);//ZAWSZE RYSOWANE PODLOZE
pos1.x=200;
pos1.y=200;
point(pos1.x, pos1.y);
//point(x2,y2);
pos2.x=mouseX;//X PUNKTU 2 PODOZA ZA CURSOREM
pos2.y=mouseY;//Y PUNKTU 2 PODOZA ZA CURSOREM
//x2=20; //X PUNKTU 2 JEST STALE
//y2=250; //Y PUNKTU 2 JEST STALE
//RAMKA GORNA1
stroke(#F2EE64);
fill(#F2EE64);
rect(0, 0, 180, 40);
fill(#ff0000);
text("x1= " + pos1.x, 65, 15);
text("y1= " + pos1.y, 65, 30);
text("x2= " + pos2.x, 125, 15);
text("y2= " + pos2.y, 125, 30);
//------------------------
//CZARNY RECT
stroke(#000000);
fill(228);
rect(370, 80, 20, 180);
rect(180, 0, 190, 40);
//------------------------
//RAMKA GORNA1
stroke(#F2EE64);
fill(#F2EE64);
//rect(180,0,190,40);
fill(#ff0000);
text("CZUJNIK= " + CZUJNIK, 180, 20);
//------------------------
CZUJNIK=(rysuj2(pos1, pos2));
k=k+1;
//println(k);
//if(k==1) //ZABEZPIECZENIA JESLI SPRAWDZAM 1 KLATKE
//stop();
}
//KONIEC
//-------------------------------------------
//-------------------------------------------
//FUNKCJE
float zao(float x)
{
x=x*10;
x=round(x);
x=x/10;
return x;
}
//-------------------------------------------
//-------------------------------------------
float rysuj2(PVector pos1, PVector pos2)
{
//a i b to wspólczynniki
float a=0;
float b=0;
color black=#000000;//KOLOR CZARNY
color cp;//BADANY KOLOR
float odl=0;
//------------------------
//OBLICZENIA FUNKCJI
a=(pos2.y-pos1.y);
a=a/(pos2.x-pos1.x);
b=pos1.y-a*pos1.x;
println(a + " " + b);
//------------------------
//------------------------
stroke(#FF0000);
if (abs(a) > 2) // That's the criterion to change increment kind
{
boolean incr = pos1.y > pos2.y;
y = int(pos1.y);
while (Error != 1)
{
x = int((y - b) / a);
if (y==height)
{
Error=1;
}
if (y==0)
{
Error=1;
}
stroke(#ff0000);
// println(pos2.x+" "+y);
cp=get(x, y);
if (cp==black)
{
Error=1;
odl=(pos1.y-y);
}
point(x, y);
if (incr) y++;
else y--;
}
}
else
//-------------------------------------------
//-------------------------------------------
{
boolean incr = pos1.x > pos2.x;
x = int(pos1.x);
while (Error != 1)
{
y = int(a * x + b);
if (x==width)
{
Error=1;
}
if (x==0)
{
Error=1;
}
if (y==Y)
{
Error=1;
}
if (y==0)
{
Error=1;
}
//------------------------
cp=get(x, y);
if (cp==black)
{
Error=1;
odl=(pos1.x-x)*(pos1.x-x)+(pos1.y-y)*(pos1.y-y);
odl=sqrt(odl);
}
stroke(#FF00FF);
point(x, y);
if (incr) x++;
else x--;
}
}
Error=0;
x=0;
y=0;
return odl;
}
//-------------------------------------------
//-------------------------------------------
void keyPressed()
{
if (key=='q')
{
exit();
}
}
//-------------------------------------------
//-------------------------------------------

alexx600

Re: Re: laser distance sensor

1 year ago

Thanks a lot:) Yes I am from Poland.I didn't think that I will need help . Next time I will write in English just in case.It can be stupid but I don't know that i can use simple "width" and "height".You are right red letter on black screen wasn't easily readable.

Using "while" was really good :) I do not know why i didn't think about that:)

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