collision_triangle

// in_triangle(x1,y1,x2,y2,x3,y3,xx,yy) : Checks if (xx,yy) is inside the triangle
// formed by (x1,y1), (x2,y2), and (x3,y3)
var x1,x2,x3,y1,y2,y3,xx,yy,a0,a1,a2,a3;
x1 = argument0;
y1 = argument1;
x2 = argument2;
y2 = argument3;
x3 = argument4;
y3 = argument5;
xx = argument6;
yy = argument7;
// Okay, so you really don't have to declare variables like I just did
// It just saves me typing later and helps me to remember what each argument is
a0 = abs((x2-x1)*(y3-y1)-(x3-x1)
*(y2-y1));
a1 = abs((x1-xx)*(y2-yy)-(x2-xx)
*(y1-yy));
a2 = abs((x2-xx)*(y3-yy)-(x3-xx)
*(y2-yy));
a3 = abs((x3-xx)*(y1-yy)-(x1-xx)
*(y3-yy));
return (abs(a1+a2+a3-a0) <= 1/256);