Implement RNG module

CMakeLists.txt

@@ -12,6 +12,7 @@ add_library(batomorph
   src/camera.c
   src/ff.c
   src/obj.c
+  src/rng.c
   src/vec3.c
 )
 configure_target(batomorph)

demo.c

@@ -1,6 +1,7 @@
 #include "camera.h"
 #include "ff.h"
 #include "obj.h"
+#include "rng.h"
 
 #include <unistd.h>
 
@@ -23,9 +24,13 @@ static pix_t pixbuf[W * H];
 
 int main()
 {
+	rng_init();
+
 	img_t img = { .pix = pixbuf };
 	camera_t camera = camera_init(camera_pos, FOCAL_LEN, VIEWPORT_H, W, H);
 	camera_render(&camera, scene, NELEMS(scene), &img);
+
 	ff_write(STDOUT_FILENO, img);
+
 	return 0;
 }

include/rng.h

@@ -0,0 +1,11 @@
+#ifndef RNG_H
+#define RNG_H
+
+#include "vec3.h"
+
+void rng_init();
+
+double rng_double();
+vec3_t rng_vec3();
+
+#endif

src/rng.c

@@ -0,0 +1,23 @@
+#include "rng.h"
+
+#include <limits.h>
+#include <stdlib.h>
+#include <sys/time.h>
+
+void rng_init()
+{
+	struct timeval tv;
+	gettimeofday(&tv, NULL);
+	srand(tv.tv_usec);
+}
+
+double rng_double()
+{
+	return 2.0 * (double)rand() / (double)INT_MAX - 1.0;
+}
+
+vec3_t rng_vec3()
+{
+	const vec3_t v = { rng_double(), rng_double(), rng_double() };
+	return vec3_unit(v);
+}