From 313619d8d524e1d56b5596646ee3ea89932a4b23 Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cobrien@witekio.com>
Date: Tue, 23 Sep 2025 15:35:26 +0100
Subject: [PATCH] Add progress output

---
 src/camera.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/camera.c b/src/camera.c
index 999df26..d923870 100644
--- a/src/camera.c
+++ b/src/camera.c
@@ -5,6 +5,8 @@
 
 #include <float.h>
 #include <math.h>
+#include <stdatomic.h>
+#include <stdio.h>
 #include <threads.h>
 
 #define MAX_ITER 10
@@ -24,6 +26,7 @@ typedef struct {
 	pix_t *pixels;
 	rng_t rng;
 	unsigned start_y, row_count, scene_count;
+	atomic_uint *progress;
 } work_slice_t;
 
 static const vec3_t lightblue = { 0.4, 0.6, 1.0 };
@@ -104,6 +107,8 @@ static int render_thread(void *arg)
 
 			setpix(colour, slice->pixels + (w * y + x));
 		}
+
+		atomic_fetch_add(slice->progress, 1);
 	}
 
 	return 0;
@@ -143,8 +148,11 @@ void camera_render(
 	img_out->w = camera->img_width;
 	img_out->h = camera->img_height;
 
-	const unsigned rows_per_thread = img_out->h / NTHREADS;
-	const unsigned rem_rows = img_out->h % NTHREADS;
+	const unsigned rows = camera->img_height;
+	const unsigned rows_per_thread = rows / NTHREADS;
+	const unsigned rem_rows = rows % NTHREADS;
+
+	atomic_uint progress = 0;
 
 	thrd_t threads[NTHREADS];
 	work_slice_t slices[NTHREADS];
@@ -160,9 +168,20 @@ void camera_render(
 		if (rem_rows != 0 && i == NTHREADS - 1)
 			slices[i].row_count += rem_rows;
 
+		slices[i].progress = &progress;
+
 		thrd_create(threads + i, render_thread, slices + i);
 	}
 
+	const unsigned digits = (unsigned)floor(log(rows) / log(10)) + 1;
+	unsigned done;
+	do {
+		thrd_sleep(&(struct timespec) { .tv_nsec = 50'000'000 }, nullptr);
+		done = atomic_load(&progress);
+		fprintf(stderr, "\r[%*d/%d]", digits, done, rows);
+		fflush(stderr);
+	} while (done < rows);
+
 	for (unsigned i = 0; i < NTHREADS; ++i)
 		thrd_join(threads[i], 0);
 }