From 97c31c7548f8c64eefddab9f68593b7e6eb911a2 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Tue, 20 Nov 2018 11:01:46 -0700
Subject: [PATCH] Add normalMatrix uniform

---
 Terrain2/Renderer.swift | 6 +++++-
 Terrain2/ShaderTypes.h  | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Terrain2/Renderer.swift b/Terrain2/Renderer.swift
index 12ce84e..0e91215 100644
--- a/Terrain2/Renderer.swift
+++ b/Terrain2/Renderer.swift
@@ -206,9 +206,13 @@ class Renderer: NSObject, MTKViewDelegate {
         let rotationAxis = float3(0, 1, 0)
         let modelMatrix = matrix4x4_rotation(radians: rotation, axis: rotationAxis)
         let viewMatrix = matrix4x4_translation(0.0, -2.0, -8.0)
-        uniforms[0].modelViewMatrix = simd_mul(viewMatrix, modelMatrix)
+        let modelViewMatrix = simd_mul(viewMatrix, modelMatrix)
+        uniforms[0].modelViewMatrix = modelViewMatrix
         rotation += 0.003
 
+        let rotSclModelViewMatrix = float3x3(modelViewMatrix.columns.0.xyz, modelViewMatrix.columns.1.xyz, modelViewMatrix.columns.2.xyz)
+        uniforms[0].normalMatrix = rotSclModelViewMatrix.inverse.transpose
+
         uniforms[0].terrainDimensions = terrain.dimensions
         uniforms[0].terrainSegments = terrain.segments
     }
diff --git a/Terrain2/ShaderTypes.h b/Terrain2/ShaderTypes.h
index 0b839fe..d691313 100644
--- a/Terrain2/ShaderTypes.h
+++ b/Terrain2/ShaderTypes.h
@@ -58,6 +58,7 @@ typedef NS_ENUM(NSInteger, GeneratorTextureIndex) {
 typedef struct {
     matrix_float4x4 projectionMatrix;
     matrix_float4x4 modelViewMatrix;
+    matrix_float3x3 normalMatrix;
     packed_float2 terrainDimensions;
     packed_uint2 terrainSegments;
 } Uniforms;