add rotation field to obj

data/scripts/classes/obj.lua

@@ -3,6 +3,7 @@
 ---@field texture string
 ---@field texture_size integer
 ---@field position Vector3
+---@field rotation Vector3
 ---@field triangles table
 local Obj = {}
 
@@ -50,7 +51,7 @@ function Obj.create(model, texture, position)
     texture = texture.file,
     texture_size = texture.size,
     position = pos:copy(),
-
+    rotation = Vector3(),
     triangles = {}
   }
   obj.position = obj.position:copy()
@@ -112,12 +113,19 @@ function Obj.create(model, texture, position)
   return obj
 end
 
+local function rotate_vertex(obj, v)
+  local vec = Vector3(v)
+  --- YXZ (yaw pitch roll) minimizes gimbal lock
+  -- return vec:rotate(Vector3.UP, obj.rotation.y):rotate(Vector3.LEFT, obj.rotation.x):rotate(Vector3.FORWARD, obj.rotation.z)
+  return vec:rotate(Vector3.UP, obj.rotation.y):rotate(Vector3.LEFT, obj.rotation.x):rotate(Vector3.FORWARD, obj.rotation.z)
+end
+
 function Obj:draw()
   for _, triangle in ipairs(self.triangles) do
     local newt = util.shallow_copy(triangle)
-    newt.v0 = Vector3(triangle.v0) + self.position
-    newt.v1 = Vector3(triangle.v1) + self.position
-    newt.v2 = Vector3(triangle.v2) + self.position
+    newt.v0 = rotate_vertex(self, triangle.v0) + self.position
+    newt.v1 = rotate_vertex(self, triangle.v1) + self.position
+    newt.v2 = rotate_vertex(self, triangle.v2) + self.position
     draw_triangle(newt)
   end
 end