From 6ae610fd7f28ba5ba7a8e0233cd6fb0ac5df4a8b Mon Sep 17 00:00:00 2001
From: Julian T <julian@jtle.dk>
Date: Mon, 23 Mar 2020 15:56:54 +0100
Subject: Random is generated by user defined function

---
 main.c   |  11 ++++++++++-
 ray.c    |  16 ++++++++--------
 ray.h    |   6 +++++-
 test.png | Bin 696052 -> 693556 bytes
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/main.c b/main.c
index 1ea89fa..36a9372 100644
--- a/main.c
+++ b/main.c
@@ -12,6 +12,12 @@
 
 char container[ CONTAINER_SIZE(5, 4, 1) ];
 
+// Implement random 
+COORD_T ray_rand(void *seed)
+{
+	return (COORD_T) rand_r( (int *)seed )  / RAND_MAX;
+}
+
 int main()
 {
 
@@ -81,10 +87,13 @@ int main()
 	// Height percentage
 	unsigned percentstep = TESTH / 100;
 	unsigned percent = 0;
+	int seed;
 
 	for (int y = TESTH; y; y--) {
 		for (int x = TESTW; x; x--) {
-			color_t *c = ray_trace(&cont->space, x, y, 2);
+			// Random seed
+			seed = x * y;
+			color_t *c = ray_trace(&cont->space, x, y, 2, &seed);
 
 			if (c) {
 				pgm_write_pixel(stdout, c);
diff --git a/ray.c b/ray.c
index 07807c0..b2df086 100644
--- a/ray.c
+++ b/ray.c
@@ -191,7 +191,7 @@ static void direct_light(space_t *s, color_t *dest, object_t *o, vector_t *N, ve
 
 // Calculates the global illumination. Pretty slow
 // https://www.scratchapixel.com/lessons/3d-basic-rendering/global-illumination-path-tracing/global-illumination-path-tracing-practical-implementation
-static void env_light(space_t *s, color_t *dest, object_t *o, vector_t *N, vector_t *eye, vector_t *point) 
+static void env_light(space_t *s, color_t *dest, object_t *o, vector_t *N, vector_t *point, void *seed) 
 {
 	// Create new coordinate system where N is up. To do this we need two more vectors for the other axises.
 	// Create the 2. by setting x or y to 0
@@ -218,8 +218,8 @@ static void env_light(space_t *s, color_t *dest, object_t *o, vector_t *N, vecto
 
 	for (unsigned i = 0; i < s->env_samples; i++) {
 		// Do the monte carlo random distribution thing from the article
-		COORD_T r1 = (COORD_T) rand() / RAND_MAX;
-		COORD_T r2 = (COORD_T) rand() / RAND_MAX;
+		COORD_T r1 = ray_rand(seed);
+		COORD_T r2 = ray_rand(seed);
 
 		COORD_T sinTheta = sqrt(1 - r1 * r1);
 		COORD_T phi = 2 * PI * r2;
@@ -256,7 +256,7 @@ static void env_light(space_t *s, color_t *dest, object_t *o, vector_t *N, vecto
 
 }
 
-int ray_trace_recur(space_t *s, color_t *dest, ray_t *ray, unsigned hop, COORD_T scale)
+int ray_trace_recur(space_t *s, color_t *dest, ray_t *ray, unsigned hop, COORD_T scale, void *seed)
 {
 	COORD_T dist;
 	color_t c;
@@ -286,7 +286,7 @@ int ray_trace_recur(space_t *s, color_t *dest, ray_t *ray, unsigned hop, COORD_T
 	
 	// Calculate environmental light
 	if (s->env_samples) {
-		env_light(s, &c, o, &N, ray->start, r.start);
+		env_light(s, &c, o, &N, r.start, seed);
 	}
 
 	// Calculate reflection vector
@@ -294,7 +294,7 @@ int ray_trace_recur(space_t *s, color_t *dest, ray_t *ray, unsigned hop, COORD_T
 		vector_scale(r.direction, &N, 2 * vector_dot(ray->direction, &N));
 		vector_sub(r.direction, ray->direction, r.direction);
 
-		ray_trace_recur(s, &c, &r, hop+1, o->m->reflective);
+		ray_trace_recur(s, &c, &r, hop+1, o->m->reflective, seed);
 	}
 
 
@@ -309,7 +309,7 @@ exit:
 	return 0;
 }
 
-color_t *ray_trace(space_t *s, unsigned int x, unsigned int y, unsigned samples)
+color_t *ray_trace(space_t *s, unsigned int x, unsigned int y, unsigned samples, void *seed)
 {
 	// Init return color. Will be accumilated with all the detected light.
 	color_t *c = color_set(NULL, 0, 0, 0);
@@ -331,7 +331,7 @@ color_t *ray_trace(space_t *s, unsigned int x, unsigned int y, unsigned samples)
 		viewpoint_ray(&s->view, r.direction, x + tmp, y + tmp);
 
 		// Run the recursive ray trace
-		ray_trace_recur(s, &ctmp, &r, 0, 1);
+		ray_trace_recur(s, &ctmp, &r, 0, 1, seed);
 
 		// Color_add will not go above 1. In this case we don't want that.
 		c->r += ctmp.r; c->g += ctmp.g; c->b += ctmp.b;
diff --git a/ray.h b/ray.h
index 74749ff..4f7fe0c 100644
--- a/ray.h
+++ b/ray.h
@@ -6,6 +6,9 @@
 #include "vector.h"
 #include "scene.h"
 
+// Random COORD_T between 0 and 1
+extern COORD_T ray_rand(void *seed);
+
 typedef struct {
     // Start is not unique so it's a pointer to save copying time
     vector_t *start;
@@ -17,6 +20,7 @@ COORD_T ray_intersect_sphere(sphere_t *s, ray_t *ray, bool skip_dist);
 COORD_T ray_intersect_plane(plane_t *p, ray_t *ray, bool skip_dist);
 
 object_t *ray_cast(space_t *s, ray_t *r, COORD_T *dist_ret, bool chk, COORD_T chk_dist);
-color_t *ray_trace(space_t *s, unsigned int x, unsigned int y, unsigned samples);
+color_t *ray_trace(space_t *s, unsigned int x, unsigned int y, unsigned samples, void *seed);
+
 
 #endif
diff --git a/test.png b/test.png
index 70122a6..10bb6ce 100644
Binary files a/test.png and b/test.png differ
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