# Position counted wrong

2 posts

 Hello, can anyone help me with the little problem? In my game i have a function which shall count if where the 2 lines will cross. One line is defined by 2 points, another is defined by angle and one point. To make everything easier, i move everything in the way that second line point is (0, 0): ` function linescollide(x0, y0, a, x11, y11, x22, y22, obj) { var x1 = x11 - x0; var y1 = (y11 - y0); var x2 = x22 - x0; var y2 = (y22 - y0); ` (First line was defined by 2 points: (x11, y11) and (x22, y22), second line was defined by a – angle and (x0, y0)) That way x0 and y0 will be zero. The function works, but y1 and y2 are counted wrong. I believe that i have to include stage height somehow. So: 1)What is the proper way to count y1 and y2? 2)Is there easier way to count if where 2 lines will cross rather than using math? 3)Is there a way to flip Y direction(so Y will not go from stage top to bottom, but from bottom to top)? You are trying to find _if_ two lines collide. This will always be the case, unless they are parallel. m1 = (y22-y11)/(x22-x11) m2 = tan(a (IN RADIANS)) or tan(v2j/v2i) if(m1!=m2) //they collide f1: Y-y1 = m(X-x1) Y – y11 = m1(X-x11) Y = (m1)X – (m1\*x11) + y11 f2: Y = (m2)X – (m2\*x0) + y0 collision, x = x, y = y (m1)X – (m1\*x11) + y11 = (m2)X – (m2\*x0) + y0 (m1-m2)X = y0 + (m1\*x11) – y11 – (m2\*x0) X = (y0 + (m1\*x11) – y11 – (m2\*x0))/(m1-m2) got X point of collision Y = (m2)X – (m2\*x0) + y0 or (m1)X – (m1\*x11) + y11 sub in X and you get Y point of collision. `function linescollide(x0, y0, a, x11, y11, x22, y22, obj){ var m1:Number = (y22-y11)/(x22-x11); var m2:Number = Math.tan(a*Math.PI/180); //If a is already in Radians, omit *Math.PI/180 if(m1!=m2){ //they collide var colX:Number = (y0 + (m1*x11) – y11 – (m2*x0))/(m1-m2); var colY:Number = (m2*colX) – (m2*x0) + y0 } }`