Sample each pixel multiple times

src/camera.c

@@ -8,6 +8,7 @@
 
 #define MAX_ITER 10
 #define MIN_T 1e-6
+#define NSAMPLES 100
 
 static const vec3_t lightblue = { 0.4, 0.6, 1.0 };
 static const vec3_t white = { 1.0, 1.0, 1.0 };
@@ -97,8 +98,15 @@ void camera_render(
 				.orig = camera->pos,
 				.dir = vec3_unit(pix),
 			};
-			const vec3_t col = trace(ray, scene, scene_count);
-			setpix(col, img_out->pix + (w * y + x));
+
+			vec3_t colour = black;
+			for (unsigned i = 0; i < NSAMPLES; ++i) {
+				const double weight = 1.0 / NSAMPLES;
+				const vec3_t sample = trace(ray, scene, scene_count);
+				colour = vec3_add(colour, vec3_scale(sample, weight));
+			}
+
+			setpix(colour, img_out->pix + (w * y + x));
 		}
 	}