From 1adef5a359fed716a3ac43ba54d919e129a673d3 Mon Sep 17 00:00:00 2001
From: Dynamitos <dynamitos15@gmail.com>
Date: Sat, 25 Jan 2025 15:11:46 +0100
Subject: [PATCH] Adding ray generation

---
 src/gpu/Renderer.cpp |  3 ---
 src/scene/Scene.cpp  | 52 ++++++++++++++++++++++++++++++++++++++------
 src/util/Camera.h    |  1 +
 3 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/src/gpu/Renderer.cpp b/src/gpu/Renderer.cpp
index dcea9e4..a63fad7 100644
--- a/src/gpu/Renderer.cpp
+++ b/src/gpu/Renderer.cpp
@@ -6,9 +6,6 @@ Renderer::Renderer()
       closestHit(nullptr), miss(nullptr), pipeline(nullptr)
 
 {
-  
-
-  vk::RayTracingPipelineCreateInfoKHR pipelineCreateInfo(0, );
 }
 
 Renderer::~Renderer() {}
diff --git a/src/scene/Scene.cpp b/src/scene/Scene.cpp
index cd8e0e6..79f2282 100644
--- a/src/scene/Scene.cpp
+++ b/src/scene/Scene.cpp
@@ -2,6 +2,7 @@
 #include "util/ModelLoader.h"
 #include <chrono>
 #include <iostream>
+#include <random>
 
 Scene::Scene()
 {
@@ -30,8 +31,9 @@ void Scene::startRender(Camera cam, RenderParameter params)
   worker = std::thread(&Scene::render, this, cam, params);
 }
 
-void Scene::render(Camera cam, RenderParameter params)
+void Scene::render(Camera camera, RenderParameter params)
 {
+  std::random_device rd;
   for (int samp = 0; samp < params.numSamples; ++samp)
   {
     if (pendingCancel)
@@ -42,15 +44,51 @@ void Scene::render(Camera cam, RenderParameter params)
       batch.jobs.push_back(
           [&](int w) -> Task
           {
+            std::mt19937 gen(rd());
+            std::uniform_real_distribution<float> rnd01(0.0, 1.0);
+            std::uniform_real_distribution<float> rnd02(0.0, 2.0);
             for (int h = 0; h < params.height; ++h)
             {
-              Ray r = Ray{.origin = glm::vec3(0.0f),
-                          .direction = glm::normalize(
-                              glm::vec3((float)std::rand() / RAND_MAX, (float)std::rand() / RAND_MAX, (float)std::rand() / RAND_MAX))};
-              bvh.traceRay(r);
+              Ray cam = Ray(camera.position, camera.direction);
+              glm::vec3 cx =
+                            glm::normalize(glm::cross(cam.direction, abs(cam.direction.y) < 0.9 ? glm::vec3(0, 1, 0) : glm::vec3(0, 0, 1))),
+                        cy = glm::cross(cx, cam.direction);
+              const glm::vec2 sdim = camera.sensorSize; // sensor size (36 x 24 mm)
 
-              accumulator[w + h * params.width] +=
-                  glm::vec3(w / float(params.width * params.numSamples), h / float(params.height * params.numSamples), 0);
+              float S_I = (camera.S_O * camera.f) / (camera.S_O - camera.f);
+
+              //-- sample sensor
+              glm::uvec2 pix = glm::uvec2(w, h);
+              glm::vec2 rnd2 = glm::vec2(rnd02(gen), rnd02(gen)); // vvv tent filter sample
+              glm::vec2 tent =
+                  glm::vec2(rnd2.x < 1 ? sqrt(rnd2.x) - 1 : 1 - sqrt(2 - rnd2.x), rnd2.y < 1 ? sqrt(rnd2.y) - 1 : 1 - sqrt(2 - rnd2.y));
+              glm::vec2 s =
+                  ((glm::vec2(pix) + 0.5f * (0.5f + glm::vec2((samp / 2) % 2, samp % 2) + tent)) / glm::vec2(params.width, params.height) -
+                   0.5f) *
+                  sdim;
+              glm::vec3 spos = cam.origin + cx * s.x + cy * s.y, lc = cam.origin + cam.direction * 0.035f; // sample on 3d sensor plane
+              glm::vec3 accrad = glm::vec3(0), accmat = glm::vec3(1); // initialize accumulated radiance and bxdf
+              Ray r = Ray(lc, normalize(lc - spos));                  // construct ray
+
+              //-- setup lens
+              glm::vec3 lensP = lc;
+              glm::vec3 lensN = -cam.direction;
+              glm::vec3 lensX = glm::cross(lensN, glm::vec3(0, 1, 0)); // the exact vector doesnt matter
+              glm::vec3 lensY = glm::cross(lensN, lensX);
+
+              glm::vec3 lensSample = lensP + rnd01(gen) * camera.A * lensX + rnd01(gen) * camera.A * lensY;
+
+              glm::vec3 focalPoint = cam.origin + (camera.S_O + S_I) * cam.direction;
+              float t = glm::dot(focalPoint - r.origin, lensN) / glm::dot(r.direction, lensN);
+              glm::vec3 focus = r.origin + t * r.direction;
+              r = Ray(lensSample, normalize(focus - lensSample)); // TODO: Fix lens
+
+              auto intersection = bvh.traceRay(r);
+
+              if (intersection.has_value())
+              {
+                accumulator[w + h * params.width] = intersection->albedo;
+              }
             }
             co_return;
           }(w));
diff --git a/src/util/Camera.h b/src/util/Camera.h
index 9115398..b6c9c25 100644
--- a/src/util/Camera.h
+++ b/src/util/Camera.h
@@ -8,4 +8,5 @@ struct Camera
     glm::vec2 sensorSize = glm::vec2(0.036, 0.024);
     float S_O = 6.9;
     float f = 0.7;
+    float A = 0.35;
 };
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