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mathluageometry

Lua math, detect if rectangle is inside the other rectangle

I'm trying to make a UI system similar to GMOD's vgui library (https://wiki.facepunch.com/gmod/vgui). In this library you can create an element, then child of that element. The child of a parent element will be clipped by the parent element's size. So if you have a redbox that has a width and height of 100, the the child element's of the redbox CANNOT be drawn outside the redbox and so on.

Solution 
  • local parent_x = Parent.INTERNAL_VARS.draw_start_x
local parent_y = Parent.INTERNAL_VARS.draw_start_y
local parent_width  = Parent._width
local parent_height = Parent._height

v.INTERNAL_VARS.draw_start_x = parent_x + v.x
v.INTERNAL_VARS.draw_start_y = parent_y + v.y

local child_x = v.INTERNAL_VARS.draw_start_x
local child_y = v.INTERNAL_VARS.draw_start_y
local child_width  = v._width
local child_height = v._height

local x = math.max(child_x, parent_x)
local y = math.max(child_y, parent_y)

draw.DrawOutlinedRect(
   x,
   y,
   math.min(child_x + child_width,  parent_x + parent_width ) - x,
   math.min(child_y + child_height, parent_y + parent_height) - y
)