From 2f8726b705c14eed025b18fc3801a998aef4184e Mon Sep 17 00:00:00 2001
From: Stephen Seo <seo.disparate@gmail.com>
Date: Sat, 21 Aug 2021 17:32:27 +0900
Subject: [PATCH] EX02 Fixes

---
 .../src/rayTracer.cpp                         | 48 +++++++++----------
 .../src/rayTracer.hpp                         |  4 +-
 2 files changed, 24 insertions(+), 28 deletions(-)

diff --git a/example02_threaded_raytracing/src/rayTracer.cpp b/example02_threaded_raytracing/src/rayTracer.cpp
index eebef8c..00eb9e1 100644
--- a/example02_threaded_raytracing/src/rayTracer.cpp
+++ b/example02_threaded_raytracing/src/rayTracer.cpp
@@ -10,15 +10,14 @@
 const float PI = std::acos(-1.0f);
 
 glm::vec3 Ex02::RT::Internal::defaultSpherePos() {
-    // the default model matrix pushes everything back 2 units,
-    // so it should be ok to define the sphere at location 0
-    return glm::vec3{0.0f, 0.0f, 0.0f};
+    return glm::vec3{0.0f, 0.0f, -2.5f};
 }
 
 glm::vec3 Ex02::RT::Internal::defaultLightPos() {
-    return glm::vec3{1.0f, 1.0f, 0.0f};
+    return glm::vec3{4.0f, 4.0f, 0.0f};
 }
 
+/*
 glm::mat4x4 Ex02::RT::Internal::defaultMVP() {
     glm::mat4x4 mvp = glm::perspective(
         PI / 2.0f,
@@ -38,6 +37,7 @@ glm::mat4x4 Ex02::RT::Internal::defaultMVP() {
 
     return mvp;
 }
+*/
 
 std::optional<glm::vec3> Ex02::RT::Internal::rayToSphere(
         glm::vec3 rayPos,
@@ -73,13 +73,18 @@ std::optional<glm::vec3> Ex02::RT::Internal::rayToSphere(
             + rayDir.y * tempVec.y
             + rayDir.z * tempVec.z;
         float dist = -temp - std::sqrt(delta);
-        if(dist < 0.0f) {
-            dist = -temp + std::sqrt(delta);
-            if(dist < 0.0f) {
+        float dist2 = -temp + std::sqrt(delta);
+        float min = dist > dist2 ? dist2 : dist;
+        float max = dist > dist2 ? dist : dist2;
+        if(min < 0.0f) {
+            if(max < 0.0f) {
                 return {};
+            } else {
+                return {rayPos + rayDir * max};
             }
+        } else {
+            return {rayPos + rayDir * min};
         }
-        return {rayPos + rayDir * dist};
     }
 }
 
@@ -97,46 +102,39 @@ std::vector<unsigned char> Ex02::RT::renderGraySphere(
         float sphereRadius,
         int threadCount,
         glm::vec3 spherePos,
-        glm::vec3 lightPos,
-        glm::mat4x4 mvp) {
+        glm::vec3 lightPos) {
     std::vector<unsigned char> grayscalePixels;
     grayscalePixels.resize(outputWidth * outputHeight);
-
-//    glm::vec3 tr_spherePos = mvp * glm::vec4{spherePos, 1.0f};
-//    glm::vec3 tr_lightPos = mvp * glm::vec4{lightPos, 1.0f};
-    glm::vec3 tr_spherePos = glm::vec3{0.0f, 0.0f, -2.0f};
-    glm::vec3 tr_lightPos = glm::vec3{1.0f, 1.0f, 0.0f};
     glm::vec3 rayPos{0.0f, 0.0f, 0.0f};
     if(threadCount == 1) {
         for(unsigned int j = 0; j < outputHeight; ++j) {
-            float offsetY = ((float)j - ((float)outputHeight / 2.0f));
+            float offsetY = ((float)j + 0.5f - ((float)outputHeight / 2.0f));
             for(unsigned int i = 0; i < outputWidth; ++i) {
-                float offsetX = ((float)i - ((float)outputWidth / 2.0f));
+                float offsetX = ((float)i + 0.5f - ((float)outputWidth / 2.0f));
                 glm::vec3 rayDir = glm::vec3{
                     offsetX, offsetY, -EX02_RAY_TRACER_DRAW_PLANE};
                 auto rayResult = Internal::rayToSphere(
-                        rayPos, rayDir, tr_spherePos, sphereRadius);
+                    rayPos, rayDir, spherePos, sphereRadius);
                 if(rayResult) {
-                    glm::vec3 toLight = *rayResult - tr_lightPos;
+                    glm::vec3 toLight = lightPos - *rayResult;
                     toLight /= std::sqrt(
                         toLight.x * toLight.x
                         + toLight.y * toLight.y
                         + toLight.z * toLight.z);
-                    glm::vec3 toLightPos = *rayResult + toLight * 2.4f;
+                    glm::vec3 toLightPos = *rayResult + toLight;
                     auto collResult = Internal::rayToSphere(
-                        toLightPos, toLight, tr_spherePos, sphereRadius);
+                        toLightPos, toLight, spherePos, sphereRadius);
                     if(collResult) {
                         continue;
                     }
 
-                    glm::vec3 resultToLight = tr_lightPos - *rayResult;
                     glm::vec3 resultToOrigin = rayPos - *rayResult;
                     float angle = Internal::angleBetweenRays(
-                            resultToLight,
-                            resultToOrigin);
+                        toLight,
+                        resultToOrigin);
                     if(angle <= PI && angle >= 0.0f) {
                         grayscalePixels.at(i + j * outputWidth) =
-                            (1.0f - angle / PI) * 255.0f;
+                            (angle / PI) * 255.0f;
                     }
                 }
             }
diff --git a/example02_threaded_raytracing/src/rayTracer.hpp b/example02_threaded_raytracing/src/rayTracer.hpp
index fef06b5..d0dd96c 100644
--- a/example02_threaded_raytracing/src/rayTracer.hpp
+++ b/example02_threaded_raytracing/src/rayTracer.hpp
@@ -20,7 +20,6 @@ namespace RT {
 namespace Internal {
     glm::vec3 defaultSpherePos();
     glm::vec3 defaultLightPos();
-    glm::mat4x4 defaultMVP();
 
     std::optional<glm::vec3> rayToSphere(
         glm::vec3 rayPos,
@@ -39,8 +38,7 @@ std::vector<unsigned char> renderGraySphere(
     float sphereRadius,
     int threadCount = 1,
     glm::vec3 spherePos = Internal::defaultSpherePos(),
-    glm::vec3 lightPos = Internal::defaultLightPos(),
-    glm::mat4x4 mvp = Internal::defaultMVP()
+    glm::vec3 lightPos = Internal::defaultLightPos()
 );
 
 void writeGrayscaleToFile(