add obj loader

data/models/unit_cube.obj

@@ -0,0 +1,38 @@
+# Blender 4.0.2
+# www.blender.org
+o Cube
+v -0.500000 -0.500000 0.500000
+v -0.500000 0.500000 0.500000
+v -0.500000 -0.500000 -0.500000
+v -0.500000 0.500000 -0.500000
+v 0.500000 -0.500000 0.500000
+v 0.500000 0.500000 0.500000
+v 0.500000 -0.500000 -0.500000
+v 0.500000 0.500000 -0.500000
+vn -1.0000 -0.0000 -0.0000
+vn -0.0000 -0.0000 -1.0000
+vn 1.0000 -0.0000 -0.0000
+vn -0.0000 -0.0000 1.0000
+vn -0.0000 -1.0000 -0.0000
+vn -0.0000 1.0000 -0.0000
+vt 0.375000 0.000000
+vt 0.625000 0.000000
+vt 0.625000 0.250000
+vt 0.375000 0.250000
+vt 0.625000 0.500000
+vt 0.375000 0.500000
+vt 0.625000 0.750000
+vt 0.375000 0.750000
+vt 0.625000 1.000000
+vt 0.375000 1.000000
+vt 0.125000 0.500000
+vt 0.125000 0.750000
+vt 0.875000 0.500000
+vt 0.875000 0.750000
+s 0
+f 1/1/1 2/2/1 4/3/1 3/4/1
+f 3/4/2 4/3/2 8/5/2 7/6/2
+f 7/6/3 8/5/3 6/7/3 5/8/3
+f 5/8/4 6/7/4 2/9/4 1/10/4
+f 3/11/5 7/6/5 5/8/5 1/12/5
+f 8/5/6 4/13/6 2/14/6 6/7/6

data/scripts/classes/obj.lua

@@ -0,0 +1,125 @@
+---@class Obj
+---@field model string
+---@field texture string
+---@field texture_size integer
+---@field position Vector3
+---@field triangles table
+local Obj = {}
+
+local Vector3 = require "types.vector3"
+
+Obj.__index = Obj
+
+local function string_split(str, delimiter)
+  local res = {}
+  local i = 0
+  local f
+  local match = '(.-)' .. delimiter .. '()'
+  
+  if string.find(str, delimiter) == nil then
+    return {str}
+  end
+  
+  for sub, j in string.gmatch(str, match) do
+    i = i + 1
+    res[i] = sub
+    f = j
+  end
+  
+  if i ~= 0 then
+    res[i+1] = string.sub(str, f)
+  end
+  
+  return res
+end
+
+---parses the obj file and triangulates it for drawing
+---@param model string path to obj model
+---@param texture {file: string, size: number}
+---@param position Vector3?
+---@return Obj
+function Obj.create(model, texture, position)
+  local pos
+  if position ~= nil then
+    pos = position
+  else
+    pos = Vector3()
+  end
+  local obj = {
+    model = model,
+    texture = texture.file,
+    texture_size = texture.size,
+    position = pos:copy(),
+
+    triangles = {}
+  }
+  obj.position = obj.position:copy()
+  setmetatable(obj, Obj)
+  -- adapted from https://github.com/karai17/lua-obj/blob/master/obj_loader.lua
+  -- Copyright (c) 2014 Landon Manning - LManning17@gmail.com - LandonManning.com
+  -- MIT
+  local file = file_read{file = obj.model}
+  local lines = string_split(file, "\r?\n")
+  local obj_data = {
+    v = {},
+    vt = {},
+    f = {},
+  }
+  for _, line in ipairs(lines) do
+    local l = string_split(line, "%s+")
+    if l[1] == "v" then
+      local v = {
+        x = tonumber(l[2]),
+        y = tonumber(l[3]),
+        z = tonumber(l[4]),
+      }
+      table.insert(obj_data.v, v)
+    elseif l[1] == "vt" then
+      local vt = {
+        x = tonumber(l[2]) * obj.texture_size,
+        y = tonumber(l[3]) * obj.texture_size,
+      }
+      table.insert(obj_data.vt, vt)
+    elseif l[1] == "f" then
+      local f = {}
+      for i = 2, #l do
+        local split = string_split(l[i], "/")
+        local v = {}
+
+        v.v = tonumber(split[1])
+        if split[2] ~= "" then v.vt = tonumber(split[2]) end
+        -- v.vn = tonumber(split[3])
+
+        table.insert(f, v)
+      end
+      table.insert(obj_data.f, f)
+    end
+  end
+  for _, face in ipairs(obj_data.f) do
+    for i = 2, #face - 1 do
+      local triangle = {
+        v0 = obj_data.v[face[1].v],
+        v1 = obj_data.v[face[i].v],
+        v2 = obj_data.v[face[i + 1].v],
+        uv0 = obj_data.vt[face[1].vt],
+        uv1 = obj_data.vt[face[i].vt],
+        uv2 = obj_data.vt[face[i + 1].vt],
+        texture = obj.texture
+      }
+      table.insert(obj.triangles, triangle)
+    end
+  end
+  return obj
+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
+    draw_triangle(newt)
+  end
+end
+
+return Obj

data/scripts/game.lua

@@ -3,6 +3,10 @@ local player = require "classes.player"
 local Vector3 = require "types.vector3"
 local List = require "types.list"
 
+local Obj = require "classes.obj"
+
+local cube = Obj.create("models/unit_cube.obj", {file = "images/measure002a.png", size = 512}, Vector3(0, 1, 0))
+
 local Feed = require "classes.feed"
 ---@type List
 local feed = List()
@@ -41,10 +45,6 @@ function game_tick()
   -- ctx.initialization_needed is true first frame and every time dynamic reload is performed
   if ctx.initialization_needed then
     audio_play{audio = "music/bg1.xm", loops = true, channel = "music"}
-    -- ctx.udata persists on reload
-    ctx.udata = {
-      capture = false,
-    }
     player.ThrowPressed:connect(create_feed)
 
     -- spawn some ducks
@@ -55,7 +55,13 @@ function game_tick()
       duck.SeekFeed:connect(duck_seek_feed)
       duck.index = i
     end
-
+  end
+  
+  -- ctx.udata persists on reload
+  if ctx.udata == nil then
+    ctx.udata = {
+      capture = false,
+    }
   end
 
   ctx.mouse_capture = ctx.udata.capture
@@ -80,4 +86,7 @@ function game_tick()
     texture_region = { x = 0, y = 0, w = 512, h = 512 },
   }
   draw_quad(util.merge(q, params))
+  cube.position.x = math.sin(ctx.frame_number * 0.01)
+  cube.position.z = math.cos(ctx.frame_number * 0.01)
+  cube:draw()
 end