CODEWITHSUNDEEP
c++calgorithmgraphicsvector
jmasterx
jmasterx

Reputation: 54193

Help with connected outlines

I'm making a vector drawing application. I use this algorithm to generate outlines.

This algorthm works well, except it does not close the outline as seen here: alt text http://img716.imageshack.us/img716/2633/noclosure.png

I'm not sure what I should do to ensure that it always closes the outline. I tried inserting the last vertex at position[0] in the std::vector but this did not help.

DOUBLEPOINT looks like:

struct DOUBLEPOINT {
double point[2];
};

How can I make it so it always properly closes the shape even on sharp corners?

Thanks

Upvotes: 0

Views: 79

Answers (3)

bta
bta

Reputation: 45087

Try appending a copy of the first and second points to the end of the vector before plotting it. Your first and last line segment will overlap, but it should ensure that all the points are connected and all corners are rounded similarly.

Upvotes: 1

Gianni
Gianni

Reputation: 4390

How about:

for( size_t i = 0; i < input.size(); ++i )
{
    POINTFLOAT cur;
    POINTFLOAT nxt;

    if( i == input.size() - 1 )
    {
       cur.x = input[i].point[0];
       cur.y = input[i].point[1];

       nxt.x = input[0].point[0];
       nxt.y = input[0].point[1];
    }
    else
    {
       cur.x = input[i].point[0];
       cur.y = input[i].point[1];

       nxt.x = input[i+1].point[0];
       nxt.y = input[i+1].point[1];
    }

Upvotes: 1

genpfault
genpfault

Reputation: 52167

I usually just use modulus:

nxt = input[(i+1) % input.size()];

Upvotes: 1

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