Realistic sniper rifle scope in LUA

Entry posted by tipforeveryone September 25, 2016

5,882 views

https://www.leadwerks.com/community/blogs/entry/1775-realistic-sniper-rifle-scope-in-lua/

This tutorial will help you to make something like this

Step 1: Prepare scope model

In 3D application, import your 3d scope model and adjust its pivot point. Make sure the pivot's position looks like image below. This step is extreme important! The position of pivot point is the position of Scope Camera Render Target

If you use Blender, press Ctrl + A > Location / Scale / Rotation to reposition scope's pivot

Example model file attached at the bottom of this entry

Export this scope model to FBX in Leadwerks

Step 2: Build scope's components

According to above concept, we have 3 main components: Scope Camera, Scope Model, Scope Camera Render Target. We will create them, one by one using LUA

First, import Scope Model to the scene > create a new Script > rename it to "Scope.lua" > apply script to Scope Model.

Here is the code

Script.scopePhysicalLength = 1
--This is actually the distance from Scope Camera to Scope Camera Render Target
Script.scopeResolution = 512
--Scope render resolution, higer = better look = performance cost, 256 is fine
Script.scopeFOV = 4

function Script:Start()
--Create Scope Camera Render Target (SCRT) first
self.scopeTexture = Texture:Create(self.scopeResolution,self.scopeResolution)
self.scopeMaterial = Material:Create()
self.scopeMaterial:SetShader("Shaders/Model/Diffuse.shader")
self.scopeMaterial:SetColor(1,1,1,1)
self.scopeMaterial:SetSortMode(true)
--"SortMode = true" will eliminate the unwanted black shade in SCRT when render
self.scopeMaterial:SetTexture(self.scopeTexture)

self.scopeRenderTarget = Model:Cylinder(32)
self.scopeRenderTarget:SetParent(self.entity)
self.scopeRenderTarget:SetPosition(0,0,0)
self.scopeRenderTarget:SetRotation(0,0,0)
self.scopeRenderTarget:SetScale(0.065,0,0.065)
--X and Z axis of scale should be adjusted to make sure SCRT is fit inside Scope Model
self.scopeRenderTarget:SetMaterial(self.scopeMaterial)

--Create Scope Camera
self.scopeCamera = Camera:Create()
self.scopeCamera:SetParent(self.entity)
self.scopeCamera:SetPosition(0,self.scopePhysicalLength,0)
self.scopeCamera:SetRotation(-90,0,0)
self.scopeCamera:SetClearColor(1,1,1)
self.scopeCamera:SetFOV(self.scopeFOV)
--this FOV value should be smaller than 20 to make the zoom effect
self.scopeCamera:SetRenderTarget(self.scopeTexture)

--Create Scope Reticle
self.scopeReticle = Model:Cylinder(32)
self.scopeReticle:SetParent(self.entity)
self.scopeReticle:SetPosition(0,-0.001,0) --make sure Reticle stays between main camera and CSRT
self.scopeReticle:SetRotation(0,0,0)
self.scopeReticle:SetScale(0.065,0,0.065)
--This reticle should be the same size as SCRT
local mtl = Material:Load("Materials/reticle.mat")
self.scopeReticle:SetMaterial(mtl)
end

Step 3: Check the resuilt

It should look like this