wallhack: flipping entity coordinates, so that they are rendered in front

augment/modules/wh.lua

@@ -1,4 +1,42 @@
 return function()
+    local playerLookVector = nil
+
+    local function updateLookVector()
+        -- pitch:
+        --     0 => positive Z
+        --     90 => negative X
+        local yawr = math.rad(player.yaw)
+        local pitchr = math.rad(player.pitch)
+        local cosPitch = math.cos(pitchr)
+        local x = cosPitch * -math.sin(yawr)
+        local z = cosPitch *  math.cos(yawr)
+        local y = math.sin(pitchr)
+        playerLookVector = {x, y, z, x = x, y = y, z = z}
+        return playerLookVector
+    end
+
+    local function dotProduct3(u, v)
+        return u.x * v.x + u.y * v.y + u.z * v.z
+    end
+
+    local function vec3Scale(k, v)
+        return {k * v.x, k * v.y, k * v.z}
+    end
+
+    local function vec3Add(u, v)
+        return {u.x + v.x, u.y + v.y, u.z + v.z}
+    end
+
+    local function toFrontCoords(entity)
+        local dotResult = dotProduct3(entity, playerLookVector)
+        if dotResult >= 0.0 then
+            return {x = entity.x, y = entity.y, z = entity.z, flipped = false}
+        end
+        local result = vec3Add(entity, vec3Scale(-2 * dotResult, playerLookVector))
+        result.flipped = true
+        return result
+    end
+
     local cache = {}
     while _G._running do
         for id, entry in pairs(cache) do
@@ -18,14 +56,24 @@ return function()
                     cache[id].frame = canvas3d.addFrame({ 0, 0, 0 })
                     cache[id].text = cache[id].frame.addText({ 0, 0 }, "")
                 end
+                local entityFront = toFrontCoords(entity)
+                if entityFront.flipped then
+                    cache[id].cube.setColor(0x004040FF)
+                else
+                    cache[id].cube.setColor(0xFFC0C0FF)
+                end
                 cache[id].cube.setAlpha(0x20)
                 cache[id].cube.setDepthTested(false)
                 cache[id].frame.setDepthTested(false)
-                cache[id].cube.setPosition(entity.x - 0.25, entity.y - 0.25, entity.z - 0.25)
-                cache[id].frame.setPosition(entity.x, entity.y, entity.z)
+                cache[id].cube.setPosition(entityFront.x - 0.25, entityFront.y - 0.25, entityFront.z - 0.25)
+                cache[id].frame.setPosition(entityFront.x, entityFront.y, entityFront.z)
                 cache[id].text.setAlpha(0xFF)
                 cache[id].text.setText(entity.name .. "\n" .. textutils.serialize(entity))
-                cache[id].text.setColor(0xFF0000FF)
+                if entityFront.flipped then
+                    cache[id].text.setColor(0x00FFFFFF)
+                else
+                    cache[id].text.setColor(0xFF0000FF)
+                end
             end
         end
         os.sleep(0.05)