Add jitter to area light and example render of it.

source/include/light.h

@@ -12,6 +12,7 @@
 #include <tuple.h>
 #include <colour.h>
 #include <renderstat.h>
+#include <sequence.h>
 #include <stdio.h>
 
 class World;
@@ -37,6 +38,8 @@ public:
     uint32_t samples;
     uint32_t uSteps;
     uint32_t vSteps;
+    bool jitter;
+    Sequence jitterBy;
 
 public:
     Light(LightType type = POINT_LIGHT, Tuple position=Point(0, 0, 0),
@@ -44,7 +47,7 @@ public:
           { stats.addLight(); };
     Light(LightType type, Tuple corner, Tuple fullUVec, uint32_t uSteps, Tuple fullVVec, uint32_t vSteps,
             Colour intensity, bool jitter = false): type(type), corner(corner), uVec(fullUVec / uSteps), uSteps(uSteps),
-            vVec(fullVVec / vSteps), vSteps(vSteps), intensity(intensity)
+            vVec(fullVVec / vSteps), vSteps(vSteps), intensity(intensity), jitter(jitter)
     {
         this->samples = this->vSteps * this->uSteps;
         this->position = this->corner + ((fullUVec + fullVVec) / 2);

source/include/sequence.h

@@ -0,0 +1,50 @@
+/*
+ *  DoRayMe - a quick and dirty Raytracer
+ *  Sequence header
+ *
+ *  Created by Manoël Trapier
+ *  Copyright (c) 2020 986-Studio.
+ *
+ */
+#ifndef DORAYME_SEQUENCE_H
+#define DORAYME_SEQUENCE_H
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <time.h>
+
+class Sequence
+{
+private:
+    double *list;
+    uint32_t listPos;
+    uint32_t listSize;
+public:
+    Sequence() : list(nullptr), listPos(0), listSize(0) {
+        /* Need to bootstrap rand here */
+        srand(time(NULL));
+    }
+    Sequence(double *list, uint32_t listSize) : list(list), listPos(0), listSize(listSize) { };
+
+    static double frand(void)
+    {
+        return rand() / ((double) RAND_MAX);
+    }
+
+
+    double next() {
+        if (this->listSize == 0)
+        {
+           return frand();
+        }
+        else
+        {
+            uint32_t pos = this->listPos;
+            this->listPos = (this->listPos + 1) % this->listSize;
+            return this->list[pos];
+        }
+    }
+};
+
+
+#endif /* DORAYME_SEQUENCE_H */

source/shapes/light.cpp

@@ -47,5 +47,14 @@ double Light::intensityAt(World &w, Tuple point)
 
 Tuple Light::pointOnLight(uint32_t u, uint32_t v)
 {
-    return this->corner + this->uVec * (u+0.5) + this->vVec * (v+0.5);
+    if (this->jitter)
+    {
+        /* For some reason, for the test to pass, I need to get the sequence for V first, then U contrary to what
+         * the bonus chapter says
+         */
+        return this->corner +
+               this->vVec * (v + this->jitterBy.next()) +
+               this->uVec * (u + this->jitterBy.next());
+    }
+    return this->corner + this->uVec * (u + 0.5) + this->vVec * (v + 0.5);
 }