Corners of a rectangle
 

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};

---

Ahh, but the horizontal and vertical distances between the player's coordinates and the coordinates of the car change, though...? (depending on the angle of the car)

i.e. if the car is facing up, the center of the car will be to the right and down of the player, whereas if the car is facing down, the center of the car will be to the left and up of the player...

Some more trigonometry is required, no?

Makes me think of GK ships, where you suddenly are floating above the sea :p