Move rendering logic into camera module

src/camera.c

@@ -1,5 +1,36 @@
 #include "camera.h"
 
+#include "ray.h"
+
+#include <float.h>
+#include <stdio.h>
+
+static const vec3_t lightblue = { 0.4, 0.6, 1.0 };
+static const vec3_t white = { 1.0, 1.0, 1.0 };
+
+static vec3_t trace(ray_t ray, const obj_t *scene, unsigned scene_count)
+{
+	bool got_hit = false;
+	hit_t hit = { .t = DBL_MAX };
+	for (unsigned i = 0; i < scene_count; ++i) {
+		if (scene[i].intersect(scene[i].params, ray, &hit, 0.0, hit.t))
+			got_hit = true;
+	}
+	if (got_hit)
+		return vec3_scale(vec3_add(hit.normal, white), 0.5);
+
+	const double a = (ray.dir.y + 1.0) / 2.0;
+	return vec3_add(vec3_scale(lightblue, a), vec3_scale(white, 1 - a));
+}
+
+static void setpix(vec3_t col, pix_t *out)
+{
+	out->r = UINT16_MAX * col.x;
+	out->g = UINT16_MAX * col.y;
+	out->b = UINT16_MAX * col.z;
+	out->a = UINT16_MAX;
+}
+
 camera_t camera_init(
     vec3_t pos, double focal_len, double viewport_height, uint32_t img_width,
     uint32_t img_height)
@@ -22,5 +53,34 @@ camera_t camera_init(
 		.pix_origin = pix_origin,
 		.x_step = x_step,
 		.y_step = y_step,
+		.img_width = img_width,
+		.img_height = img_height,
 	};
 }
+
+void camera_render(
+    const camera_t *camera, const obj_t *scene, unsigned scene_count,
+    img_t *img_out)
+{
+	const uint32_t w = img_out->w = camera->img_width;
+	const uint32_t h = img_out->h = camera->img_height;
+
+	for (unsigned y = 0; y < h; ++y) {
+		fprintf(stderr, "\r[%3d/%3d]", y, h);
+		fflush(stderr);
+
+		const vec3_t row
+		    = vec3_add(camera->pix_origin, vec3_scale(camera->y_step, y));
+		for (unsigned x = 0; x < w; ++x) {
+			const vec3_t pix = vec3_add(row, vec3_scale(camera->x_step, x));
+			const ray_t ray = {
+				.orig = camera->pos,
+				.dir = vec3_unit(pix),
+			};
+			const vec3_t col = trace(ray, scene, scene_count);
+			setpix(col, img_out->pix + (w * y + x));
+		}
+	}
+
+	fprintf(stderr, "\r[%3d/%3d]\n", h, h);
+}