Corners of a rectangle

[Loriel]

I spent half of my afternoon trying to get the blocking of Era cars right, by calculating each corner based on the center, angle, and a fixed size of 2x4 tiles of a car.
I wonder whether this is of use to anybody, or whether someone wants to make it nicer.

NPC Code:

---

  a = this.carAng;



  l = 4;  // length

  w = 2;  // width



  centerx = playerx + 1.5 - 1/16;

  centery = playery + 2   - 1/16;



  frontx = sin(a) * l;

  fronty = cos(a) * l;



  sidex = sin(a + pi/2) * w;

  sidey = cos(a + pi/2) * w;



  rectx = { centerx + frontx + sidex,  // front right

            centerx + frontx - sidex,  // front left

            centerx - frontx + sidex,  // back  right

            centerx - frontx - sidex}; // back  left



  recty = { centery - fronty - sidey,  // front right

            centery - fronty + sidey,  // front left

            centery + fronty - sidey,  // back  right

            centery + fronty + sidey}; // back  left



  for (i = 0; i < 4; i ++)

    showpoly i+1, {rectx[i],     recty[i]-0.25,

                   rectx[i]-0.5, recty[i]+0.25,

                   rectx[i]+0.5, recty[i]+0.25};

---