Move rendering functions to own module

demo.c

@@ -1,7 +1,5 @@
-#include "camera.h"
 #include "ff.h"
-#include "obj.h"
-#include "rng.h"
+#include "render.h"
 
 #include <unistd.h>
 
@@ -64,15 +62,14 @@ int main()
 		rand_obj(objs + i, &rng);
 
 	img_t img = { .pix = pixbuf };
-	camera_t camera
-	    = camera_init(camera_pos, target, FOV, W, H, SAMPLES_PER_PIXEL);
+	camera_t camera = camera_init(camera_pos, target, FOV, W, H);
 
 	const scene_t scene = {
 		.sky_colour = sky,
 		.objs = objs,
 		.obj_count = OBJ_COUNT,
 	};
-	camera_render(&camera, &scene, &img);
+	render(&camera, &scene, &img, SAMPLES_PER_PIXEL);
 
 	ff_write(STDOUT_FILENO, img);