# Edge Intersection Point

On 18/06/2015 at 12:49, xxxxxxxx wrote:

User Information:
Cinema 4D Version:   16
Platform:   Windows  ;
Language(s) :     C++  ;

---------
Hello,

I need to get the intersection point of two edges. Is there a function in the SDK which can handle this? I've searched the SDK but didn't find something useful.

Or do I have to write my own function?

Best wishes
crush4

On 19/06/2015 at 01:28, xxxxxxxx wrote:

You will have to write it yourself. I don't know of any such routine in the api.

On 19/06/2015 at 04:26, xxxxxxxx wrote:

it is quite easy, I remember I wrote or found one somewhere before, here is the function from my code:

``````
template<typename  T>
struct SNodePoint
{
T x;
T y;

SNodePoint() :
x(0), y(0)
{}

SNodePoint(T &_x, T &_y) :
x(_x), y(_y)
{}

SNodePoint(const T &_x, const T &_y) :
x(_x), y(_y)
{}

SNodePoint& operator+=(const SNodePoint& rhs)
{
x = x + rhs.x;
y = y + rhs.y;

return *this;
}

friend SNodePoint operator+(SNodePoint lhs, const SNodePoint& rhs)
{
return lhs += rhs;
}

SNodePoint& operator-=(const SNodePoint& rhs)
{
x = x - rhs.x;
y = y - rhs.y;

return *this;
}

friend SNodePoint operator-(SNodePoint lhs, const SNodePoint& rhs)
{
return lhs -= rhs;
}

SNodePoint& operator*=(const Float32& rhs)
{
x = x * rhs;
y = y * rhs;

return *this;
}

friend SNodePoint operator*(SNodePoint lhs, const Float32& rhs)
{
return lhs *= rhs;
}

friend SNodePoint operator*(Float32 lhs, const SNodePoint& rhs)
{
return rhs * lhs;
}

SNodePoint& operator/=(const Float32& rhs)
{
x = x / rhs;
y = y / rhs;

return *this;
}

friend SNodePoint operator/(SNodePoint lhs, const Float32& rhs)
{
return lhs /= rhs;
}

friend SNodePoint operator/(Float32 lhs, const SNodePoint& rhs)
{
return rhs / lhs;
}
};

Bool get_line_intersection(const SNodePoint<Float32> &p0, const SNodePoint<Float32> &p1,
const SNodePoint<Float32> &p2, const SNodePoint<Float32> & p3, SNodePoint<Float32> *pi)
{
float s02_x, s02_y, s10_x, s10_y, s32_x, s32_y, s_numer, t_numer, denom, t;
s10_x = p1.x - p0.x;
s10_y = p1.y - p0.y;
s32_x = p3.x - p2.x;
s32_y = p3.y - p2.y;

denom = s10_x * s32_y - s32_x * s10_y;
if (denom == 0)
return FALSE; // Collinear
bool denomPositive = denom > 0;

s02_x = p0.x - p2.x;
s02_y = p0.y - p2.y;
s_numer = s10_x * s02_y - s10_y * s02_x;
if ((s_numer < 0) == denomPositive)
return FALSE; // No collision

t_numer = s32_x * s02_y - s32_y * s02_x;
if ((t_numer < 0) == denomPositive)
return FALSE; // No collision

if (((s_numer > denom) == denomPositive) || ((t_numer > denom) == denomPositive))
return FALSE; // No collision
// Collision detected
t = t_numer / denom;
if (pi != NULL)
{
pi->x = p0.x + (t * s10_x);
pi->y = p0.y + (t * s10_y);
}

return TRUE;
}
``````

On 19/06/2015 at 09:27, xxxxxxxx wrote:

Thank you Mohamed, but I need it in 3D room. This is a little bit more complicated. But when I finish my code, I will post it here Greetz
crush4